National Library of Energy BETA

Sample records for dark energy survey

  1. Dark Energy Survey

    ScienceCinema (OSTI)

    Roodman, Aaron; Nord, Brian; Elliot, Ann

    2014-08-12

    Members of the Dark Energy Survey collaboration explain what they hope to learn by studying the southern sky with the world's most advanced digital camera, mounted on a telescope in Chile.

  2. Dark Energy Survey

    SciTech Connect (OSTI)

    Roodman, Aaron; Nord, Brian; Elliot, Ann

    2012-12-06

    Members of the Dark Energy Survey collaboration explain what they hope to learn by studying the southern sky with the world's most advanced digital camera, mounted on a telescope in Chile.

  3. Probing dark energy with future surveys

    E-Print Network [OSTI]

    Roberto Trotta

    2006-07-21

    I review the observational prospects to constrain the equation of state parameter of dark energy and I discuss the potential of future imaging and redshift surveys. Bayesian model selection is used to address the question of the level of accuracy on the equation of state parameter that is required before explanations alternative to a cosmological constant become very implausible. I discuss results in the prediction space of dark energy models. If no significant departure from w=-1 is detected, a precision on w of order 1% will translate into strong evidence against fluid-like dark energy, while decisive evidence will require a precision of order 10^-3.

  4. The Dark Energy Survey: more than dark energy - an overview

    E-Print Network [OSTI]

    Abbott, T; Allam, S; Aleksic, J; Amara, A; Bacon, D; Balbinot, E; Banerji, M; Bechtol, K; Benoit-Levy, A; Bernstein, G M; Bertin, E; Blazek, J; Dodelson, S; Bonnett, C; Brooks, D; Bridle, S; Brunner, R J; Buckley-Geer, E; Burke, D L; Capozzi, D; Caminha, G B; Carlsen, J; Carnero-Rosell, A; Carollo, M; Carrasco-Kind, M; Carretero, J; Castander, F J; Clerkin, L; Collett, T; Conselice, C; Crocce, M; Cunha, C E; D'Andrea, C B; da Costa, L N; Davis, T M; Desai, S; Diehl, H T; Dietrich, J P; Doel, P; Drlica-Wagner, A; Etherington, J; Estrada, J; Evrard, A E; Finley, D A; Flaugher, B; Fosalba, P; Foley, R J; Frieman, J; Garcia-Bellido, J; Gaztanaga, E; Gerdes, D W; Giannantonio, T; Goldstein, D A; Gruen, D; Gruendl, R A; Guarnieri, P; Gutierrez, G; Hartley, W; Honscheid, K; Jain, B; James, D J; Jeltema, T; Jouvel, S; Kessler, R; King, A; Kirk, D; Kron, R; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; Lima, M; Lin, H; Maia, M A G; Manera, M; Maraston, C; Marshall, J L; Martini, P; McMahon, R G; Melchior, P; Merson, A; Miller, C J; Miquel, R; Mohr, J J; Morice-Atkinson, X; Naidoo, K; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Ostrovski, F; Palmese, A; Papadopoulos, A; Peiris, H; Peoples, J; Plazas, A A; Percival, W J; Reed, S L; Romer, A K; Roodman, A; Ross, A; Rozo, E; Rykoff, E S; Sadeh, I; Sako, M; Sanchez, C; Sanchez, E; Santiago, B; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Sheldon, E; Smith, R C; Soares-Santos, M; Sobreira, F; Soumagnac, M; Suchyta, E; Sullivan, M; Tarle, G; Thaler, J; Thomas, D; Thomas, R C; Tucker, D; Vieira, J D; Vikram, V; Walker, A R; Wechsler, R H; Wester, W; Weller, J; Whiteway, L; Wilcox, H; Yanny, B; Zhang, Y; Zuntz, J

    2016-01-01

    This overview article describes the legacy prospect and discovery potential of the Dark Energy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4m Blanco Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterise dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper we focus on additional science with DES, emphasi...

  5. The Dark Energy Survey CCD imager design

    SciTech Connect (OSTI)

    Cease, H.; DePoy, D.; Diehl, H.T.; Estrada, J.; Flaugher, B.; Guarino, V.; Kuk, K.; Kuhlmann, S.; Schultz, K.; Schmitt, R.L.; Stefanik, A.; /Fermilab /Ohio State U. /Argonne

    2008-06-01

    The Dark Energy Survey is planning to use a 3 sq. deg. camera that houses a {approx} 0.5m diameter focal plane of 62 2kx4k CCDs. The camera vessel including the optical window cell, focal plate, focal plate mounts, cooling system and thermal controls is described. As part of the development of the mechanical and cooling design, a full scale prototype camera vessel has been constructed and is now being used for multi-CCD readout tests. Results from this prototype camera are described.

  6. Discovery of two gravitationally lensed quasars in the Dark Energy Survey

    E-Print Network [OSTI]

    2015-01-01

    lensed quasars in the Dark Energy Survey A. Agnello 1,? ,T.selected from the Dark Energy Survey (DES) and WISE based oncollaboration of the Dark Energy Survey 2 (DES, http://

  7. The Dark Energy Survey Data Management System

    E-Print Network [OSTI]

    Mohr, Joseph J; Beldica, Cristina; Bertin, Emmanuel; Cai, Y Dora; da Costa, Luiz; Darnell, J Anthony; Daues, Gregory E; Jarvis, Michael; Gower, Michelle; Lin, Huan; Martelli, leandro; Neilsen, Eric; Ngeow, Chow-Choong; Ogando, Ricardo; Parga, Alex; Sheldon, Erin; Tucker, Douglas; Kuropatkin, Nikolay; Stoughton, Chris

    2008-01-01

    The Dark Energy Survey collaboration will study cosmic acceleration with a 5000 deg2 griZY survey in the southern sky over 525 nights from 2011-2016. The DES data management (DESDM) system will be used to process and archive these data and the resulting science ready data products. The DESDM system consists of an integrated archive, a processing framework, an ensemble of astronomy codes and a data access framework. We are developing the DESDM system for operation in the high performance computing (HPC) environments at NCSA and Fermilab. Operating the DESDM system in an HPC environment offers both speed and flexibility. We will employ it for our regular nightly processing needs, and for more compute-intensive tasks such as large scale image coaddition campaigns, extraction of weak lensing shear from the full survey dataset, and massive seasonal reprocessing of the DES data. Data products will be available to the Collaboration and later to the public through a virtual-observatory compatible web portal. Our appr...

  8. The Dark Energy Survey Data Management System

    SciTech Connect (OSTI)

    Mohr, Joseph J.; Barkhouse, Wayne; Beldica, Cristina; Bertin, Emmanuel; Dora Cai, Y.; Nicolaci da Costa, Luiz A.; Darnell, J.Anthony; Daues, Gregory E.; Jarvis, Michael; Gower, Michelle; Lin, Huan; /Fermilab /Rio de Janeiro Observ.

    2008-07-01

    The Dark Energy Survey (DES) collaboration will study cosmic acceleration with a 5000 deg2 griZY survey in the southern sky over 525 nights from 2011-2016. The DES data management (DESDM) system will be used to process and archive these data and the resulting science ready data products. The DESDM system consists of an integrated archive, a processing framework, an ensemble of astronomy codes and a data access framework. We are developing the DESDM system for operation in the high performance computing (HPC) environments at the National Center for Supercomputing Applications (NCSA) and Fermilab. Operating the DESDM system in an HPC environment offers both speed and flexibility. We will employ it for our regular nightly processing needs, and for more compute-intensive tasks such as large scale image coaddition campaigns, extraction of weak lensing shear from the full survey dataset, and massive seasonal reprocessing of the DES data. Data products will be available to the Collaboration and later to the public through a virtual-observatory compatible web portal. Our approach leverages investments in publicly available HPC systems, greatly reducing hardware and maintenance costs to the project, which must deploy and maintain only the storage, database platforms and orchestration and web portal nodes that are specific to DESDM. In Fall 2007, we tested the current DESDM system on both simulated and real survey data. We used TeraGrid to process 10 simulated DES nights (3TB of raw data), ingesting and calibrating approximately 250 million objects into the DES Archive database. We also used DESDM to process and calibrate over 50 nights of survey data acquired with the Mosaic2 camera. Comparison to truth tables in the case of the simulated data and internal crosschecks in the case of the real data indicate that astrometric and photometric data quality is excellent.

  9. The Dark Energy Survey Data Management System

    E-Print Network [OSTI]

    Joseph J. Mohr; Wayne Barkhouse; Cristina Beldica; Emmanuel Bertin; Y. Dora Cai; Luiz da Costa; J. Anthony Darnell; Gregory E. Daues; Michael Jarvis; Michelle Gower; Huan Lin; leandro Martelli; Eric Neilsen; Chow-Choong Ngeow; Ricardo Ogando; Alex Parga; Erin Sheldon; Douglas Tucker; Nikolay Kuropatkin; Chris Stoughton

    2008-07-16

    The Dark Energy Survey collaboration will study cosmic acceleration with a 5000 deg2 griZY survey in the southern sky over 525 nights from 2011-2016. The DES data management (DESDM) system will be used to process and archive these data and the resulting science ready data products. The DESDM system consists of an integrated archive, a processing framework, an ensemble of astronomy codes and a data access framework. We are developing the DESDM system for operation in the high performance computing (HPC) environments at NCSA and Fermilab. Operating the DESDM system in an HPC environment offers both speed and flexibility. We will employ it for our regular nightly processing needs, and for more compute-intensive tasks such as large scale image coaddition campaigns, extraction of weak lensing shear from the full survey dataset, and massive seasonal reprocessing of the DES data. Data products will be available to the Collaboration and later to the public through a virtual-observatory compatible web portal. Our approach leverages investments in publicly available HPC systems, greatly reducing hardware and maintenance costs to the project, which must deploy and maintain only the storage, database platforms and orchestration and web portal nodes that are specific to DESDM. In Fall 2007, we tested the current DESDM system on both simulated and real survey data. We used Teragrid to process 10 simulated DES nights (3TB of raw data), ingesting and calibrating approximately 250 million objects into the DES Archive database. We also used DESDM to process and calibrate over 50 nights of survey data acquired with the Mosaic2 camera. Comparison to truth tables in the case of the simulated data and internal crosschecks in the case of the real data indicate that astrometric and photometric data quality is excellent.

  10. Can a galaxy redshift survey measure dark energy clustering?

    E-Print Network [OSTI]

    Masahiro Takada

    2006-08-23

    (abridged) A wide-field galaxy redshift survey allows one to probe galaxy clustering at largest spatial scales, which carries an invaluable information on horizon-scale physics complementarily to the cosmic microwave background (CMB). Assuming the planned survey consisting of z~1 and z~3 surveys with areas of 2000 and 300 square degrees, respectively, we study the prospects for probing dark energy clustering from the measured galaxy power spectrum, assuming the dynamical properties of dark energy are specified in terms of the equation of state and the effective sound speed c_e in the context of an adiabatic cold dark matter dominated model. The dark energy clustering adds a power to the galaxy power spectrum amplitude at spatial scales greater than the sound horizon, and the enhancement is sensitive to redshift evolution of the net dark energy density, i.e. the equation of state. We find that the galaxy survey, when combined with Planck, can distinguish dark energy clustering from a smooth dark energy model such as the quintessence model (c_e=1), when c_edark energy clustering and the non-relativistic neutrinos implied from the neutrino oscillation experiments, because the two effects both induce a scale-dependent modification in the galaxy power spectrum shape at largest spatial scales accessible from the galaxy survey. It is shown that a wider redshift coverage can efficiently separate the two effects by utilizing the different redshift dependences, where dark energy clustering is apparent only at low redshifts z<1.

  11. Status of the Dark Energy Survey Camera (DECam) Project

    SciTech Connect (OSTI)

    Flaugher, Brenna L.; Abbott, Timothy M.C.; Angstadt, Robert; Annis, Jim; Antonik, Michelle, L.; Bailey, Jim; Ballester, Otger.; Bernstein, Joseph P.; Bernstein, Rebbeca; Bonati, Marco; Bremer, Gale; /Fermilab /Cerro-Tololo InterAmerican Obs. /ANL /Texas A-M /Michigan U. /Illinois U., Urbana /Ohio State U. /University Coll. London /LBNL /SLAC /IFAE

    2012-06-29

    The Dark Energy Survey Collaboration has completed construction of the Dark Energy Camera (DECam), a 3 square degree, 570 Megapixel CCD camera which will be mounted on the Blanco 4-meter telescope at CTIO. DECam will be used to perform the 5000 sq. deg. Dark Energy Survey with 30% of the telescope time over a 5 year period. During the remainder of the time, and after the survey, DECam will be available as a community instrument. All components of DECam have been shipped to Chile and post-shipping checkout finished in Jan. 2012. Installation is in progress. A summary of lessons learned and an update of the performance of DECam and the status of the DECam installation and commissioning will be presented.

  12. Large Synoptic Survey Telescope: Dark Energy Science Collaboration

    E-Print Network [OSTI]

    LSST Dark Energy Science Collaboration

    2012-11-01

    This white paper describes the LSST Dark Energy Science Collaboration (DESC), whose goal is the study of dark energy and related topics in fundamental physics with data from the Large Synoptic Survey Telescope (LSST). It provides an overview of dark energy science and describes the current and anticipated state of the field. It makes the case for the DESC by laying out a robust analytical framework for dark energy science that has been defined by its members and the comprehensive three-year work plan they have developed for implementing that framework. The analysis working groups cover five key probes of dark energy: weak lensing, large scale structure, galaxy clusters, Type Ia supernovae, and strong lensing. The computing working groups span cosmological simulations, galaxy catalogs, photon simulations and a systematic software and computational framework for LSST dark energy data analysis. The technical working groups make the connection between dark energy science and the LSST system. The working groups have close linkages, especially through the use of the photon simulations to study the impact of instrument design and survey strategy on analysis methodology and cosmological parameter estimation. The white paper describes several high priority tasks identified by each of the 16 working groups. Over the next three years these tasks will help prepare for LSST analysis, make synergistic connections with ongoing cosmological surveys and provide the dark energy community with state of the art analysis tools. Members of the community are invited to join the LSST DESC, according to the membership policies described in the white paper. Applications to sign up for associate membership may be made by submitting the Web form at http://www.slac.stanford.edu/exp/lsst/desc/signup.html with a short statement of the work they wish to pursue that is relevant to the LSST DESC.

  13. Dark energy properties from large future galaxy surveys

    SciTech Connect (OSTI)

    Basse, Tobias; Bjælde, Ole Eggers; Hannestad, Steen; Hamann, Jan; Wong, Yvonne Y.Y. E-mail: oeb@phys.au.dk E-mail: sth@phys.au.dk

    2014-05-01

    We perform a detailed forecast on how well a Euclid-like survey will be able to constrain dark energy and neutrino parameters from a combination of its cosmic shear power spectrum, galaxy power spectrum, and cluster mass function measurements. We find that the combination of these three probes vastly improves the survey's potential to measure the time evolution of dark energy. In terms of a dark energy figure-of-merit defined as (?(w{sub p})?(w{sub a})){sup ?1}, we find a value of 690 for Euclid-like data combined with Planck-like measurements of the cosmic microwave background anisotropies in a 10-dimensional cosmological parameter space, assuming a ?CDM fiducial cosmology. For the more commonly used 7-parameter model, we find a figure-of-merit of 1900 for the same data combination. We consider also the survey's potential to measure dark energy perturbations in models wherein the dark energy is parameterised as a fluid with a nonstandard non-adiabatic sound speed, and find that in an optimistic scenario in which w{sub 0} deviates from -1 by as much as is currently observationally allowed, models with c-circumflex {sub s}{sup 2} = 10{sup ?6} and c-circumflex {sub s}{sup 2} = 1 can be distinguished from one another at more than 2? significance. We emphasise that constraints on the dark energy sound speed from cluster measurements are strongly dependent on the modelling of the cluster mass function; significantly weaker sensitivities ensue if we modify our model to include fewer features of nonlinear dark energy clustering. Finally, we find that the sum of neutrino masses can be measured with a 1? precision of 0.015 eV, even in complex cosmological models in which the dark energy equation of state varies with time. The 1? sensitivity to the effective number of relativistic species N{sub eff}{sup ml} is approximately 0.03, meaning that the small deviation of 0.046 from 3 in the standard value of N{sub eff}{sup ml} due to non-instantaneous decoupling and finite temperature effects can be probed with 1? precision for the first time.

  14. The signature of dark energy perturbations in galaxy cluster surveys

    SciTech Connect (OSTI)

    Abramo, L.R.; Batista, R.C. [Instituto de Física, Universidade de São Paulo, CP 66318, 05314-970, São Paulo (Brazil); Rosenfeld, R., E-mail: abramo@fma.if.usp.br, E-mail: rbatista@fma.if.usp.br, E-mail: rosenfel@ift.unesp.br [Instituto de Física Teórica, Universidade Estadual Paulista, R. Dr. Bento Teobaldo Ferraz 271, 01140-070, São Paulo (Brazil)

    2009-07-01

    Models of dynamical dark energy unavoidably possess fluctuations in the energy density and pressure of that new component. In this paper we estimate the impact of dark energy fluctuations on the number of galaxy clusters in the Universe using a generalization of the spherical collapse model and the Press-Schechter formalism. The observations we consider are several hypothetical Sunyaev-Zel'dovich and weak lensing (shear maps) cluster surveys, with limiting masses similar to ongoing (SPT, DES) as well as future (LSST, Euclid) surveys. Our statistical analysis is performed in a 7-dimensional cosmological parameter space using the Fisher matrix method. We find that, in some scenarios, the impact of these fluctuations is large enough that their effect could already be detected by existing instruments such as the South Pole Telescope, when priors from other standard cosmological probes are included. We also show how dark energy fluctuations can be a nuisance for constraining cosmological parameters with cluster counts, and point to a degeneracy between the parameter that describes dark energy pressure on small scales (the effective sound speed) and the parameters describing its equation of state.

  15. Baryon Oscillations and Dark-Energy Constraints from Imaging Surveys

    E-Print Network [OSTI]

    Derek Dolney; Bhuvnesh Jain; Masahiro Takada

    2004-09-20

    Baryonic oscillations in the galaxy power spectrum have been studied as a way of probing dark-energy models. While most studies have focused on spectroscopic surveys at high redshift, large multi-color imaging surveys have already been planned for the near future. In view of this, we study the prospects for measuring baryonic oscillations from angular statistics of galaxies binned using photometric redshifts. We use the galaxy bispectrum in addition to the power spectrum; this allows us to measure and marginalize over possibly complex galaxy bias mechanisms to get robust cosmological constraints. In our parameter estimation we allow for a weakly nonlinear biasing scheme that may evolve with redshift by two bias parameters in each of ten redshift bins. We find that a multi-color imaging survey that probes redshifts beyond one can give interesting constraints on dark-energy parameters. In addition, the shape of the primordial power spectrum can be measured to better accuracy than with the CMB alone. We explore the impact of survey depth, area, and calibration errors in the photometric redshifts on dark-energy constraints.

  16. The Dark Energy Survey: Prospects for Resolved Stellar Populations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rossetto, Bruno M [Rio de Janeiro Observ.; Santiago, Basilio X [Rio Grande do Sul U.; Rio de Janeiro Observ.; Girardi, Leo [Padua Observ.; Rio de Janeiro Observ.; Camargo, Julio I.B. [Rio de Janeiro Observ.; Balbinot, Eduardo [Rio Grande do Sul U.; Rio de Janeiro Observ.; da Costa, Luiz N [Rio de Janeiro Observ.; Yanny, Brian [Fermilab; Maia, Marcio A.G. [Rio de Janeiro Observ.; Makler, Martin [Rio de Janeiro, CBPF; Rio de Janeiro Observ.; Ogando, Ricardo L.C. [Rio de Janeiro Observ.; Pellegrini, Paulo S [Rio de Janeiro Observ.; Rio de Janeiro Observ.

    2011-05-06

    Wide angle and deep surveys, regardless of their primary purpose, always sample a large number of stars in the Galaxy and in its satellite system. We here make a forecast of the expected stellar sample resulting from the Dark Energy Survey and the perspectives that it will open for studies of Galactic structure and resolved stellar populations in general. An estimated 1.2 x 10{sup 8} stars will be sampled in DES grizY filters in the southern equatorial hemisphere. This roughly corresponds to 20% of all DES sources. Most of these stars belong to the stellar thick disk and halo of the Galaxy.

  17. THE DARK ENERGY SURVEY: PROSPECTS FOR RESOLVED STELLAR POPULATIONS

    SciTech Connect (OSTI)

    Rossetto, Bruno M.; Santiago, Basílio X.; Girardi, Léo; Camargo, Julio I. B.; Balbinot, Eduardo; da Costa, Luiz N.; Yanny, Brian; Maia, Marcio A. G.; Makler, Martin; Ogando, Ricardo L. C.; Pellegrini, Paulo S.; Ramos, Beatriz; de Simoni, Fernando; Armstrong, R.; Bertin, E.; Desai, S.; Kuropatkin, N.; Lin, H.; Mohr, J. J.; Tucker, D. L.

    2011-06-01

    Wide angle and deep surveys, regardless of their primary purpose, always sample a large number of stars in the Galaxy and in its satellite system. We here make a forecast of the expected stellar sample resulting from the Dark Energy Survey and the perspectives that it will open for studies of Galactic structure and resolved stellar populations in general. An estimated 1.2 x 108 stars will be sampled in DES grizY filters in the southern equatorial hemisphere. This roughly corresponds to 20% of all DES sources. Most of these stars belong to the stellar thick disk and halo of the Galaxy.

  18. THE DARK ENERGY SURVEY: PROSPECTS FOR RESOLVED STELLAR POPULATIONS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rossetto, Bruno M.; Santiago, Basílio X.; Girardi, Léo; Camargo, Julio I. B.; Balbinot, Eduardo; da Costa, Luiz N.; Yanny, Brian; Maia, Marcio A. G.; Makler, Martin; Ogando, Ricardo L. C.; et al

    2011-06-01

    Wide angle and deep surveys, regardless of their primary purpose, always sample a large number of stars in the Galaxy and in its satellite system. We here make a forecast of the expected stellar sample resulting from the Dark Energy Survey and the perspectives that it will open for studies of Galactic structure and resolved stellar populations in general. An estimated 1.2 x 108 stars will be sampled in DES grizY filters in the southern equatorial hemisphere. This roughly corresponds to 20% of all DES sources. Most of these stars belong to the stellar thick disk and halo of themore »Galaxy.« less

  19. System Architecture of the Dark Energy Survey Camera Readout Electronics

    SciTech Connect (OSTI)

    Shaw, Theresa; /FERMILAB; Ballester, Otger; Cardiel-Sas, Laia; Castilla, Javier; /Barcelona, IFAE; Chappa, Steve; /Fermilab; de Vicente, Juan; /Madrid, CIEMAT; Holm, Scott; Huffman, Dave; Kozlovsky, Mark; /Fermilab; Martinez, Gustavo; /Madrid, CIEMAT; Moore, Todd; /Madrid, CIEMAT /Fermilab /Illinois U., Urbana /Fermilab

    2010-05-27

    The Dark Energy Survey makes use of a new camera, the Dark Energy Camera (DECam). DECam will be installed in the Blanco 4M telescope at Cerro Tololo Inter-American Observatory (CTIO). DECam is presently under construction and is expected to be ready for observations in the fall of 2011. The focal plane will make use of 62 2Kx4K and 12 2kx2k fully depleted Charge-Coupled Devices (CCDs) for guiding, alignment and focus. This paper will describe design considerations of the system; including, the entire signal path used to read out the CCDs, the development of a custom crate and backplane, the overall grounding scheme and early results of system tests.

  20. Crowdsourcing quality control for Dark Energy Survey images

    E-Print Network [OSTI]

    Melchior, P; Drlica-Wagner, A; Rykoff, E S; Abbott, T M C; Abdalla, F B; Allam, S; Benoit-Levy, A; Brooks, D; Buckley-Geer, E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; D'Andrea, C B; da Costa, L N; Desai, S; Doel, P; Evrard, A E; Finley, D A; Flaugher, B; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Honscheid, K; James, D J; Jarvis, M; Kuehn, K; Li, T S; Maia, M A G; March, M; Marshall, J L; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Sanchez, E; Scarpine, V; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Vikram, V; Walker, A R; Wester, W; Zhang, Y

    2015-01-01

    We have developed a crowdsourcing web application for image quality control employed by the Dark Energy Survey. Dubbed the "DES exposure checker", it renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes. Users can also generate custom labels and thus help identify previously unknown problem classes. User reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. We report on the implementation of the application and our experience with its over 100 users, the majority of which are professional or prospective astronomers but not data management experts. We discuss aspects of user training and engagement, and demonstrate how problem reports have been pivotal to rapidly correct artifacts which would likely have been too subtle or infrequent to be recognized otherwise. We conclude with a number of important lessons learned, suggest possible improvements, and recommend this collective explo...

  1. Modeling the transfer function for the Dark Energy Survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chang, C.; Busha, M. T.; Wechsler, R. H.; Refregier, A.; Amara, A.; Rykoff, E.; Becker, M. R.; Bruderer, C.; Gamper, L.; Leistedt, B.; et al

    2015-03-04

    We present a forward-modelling simulation framework designed to model the data products from the Dark Energy Survey (DES). This forward-model process can be thought of as a transfer function – a mapping from cosmological and astronomical signals to the final data products used by the scientists. Using output from the cosmological simulations (the Blind Cosmology Challenge), we generate simulated images (the Ultra Fast Image Simulator, Berge et al. 2013) and catalogs representative of the DES data. In this work we simulate the 244 deg2 coadd images and catalogs in 5 bands for the DES Science Verification (SV) data. The simulationmore »output is compared with the corresponding data to show that major characteristics of the images and catalogs can be captured. We also point out several directions of future improvements. Two practical examples, star/galaxy classification and proximity effects on object detection, are then used to demonstrate how one can use the simulations to address systematics issues in data analysis. With clear understanding of the simplifications in our model, we show that one can use the simulations side-by-side with data products to interpret the measurements. This forward modelling approach is generally applicable for other upcoming and future surveys. As a result, it provides a powerful tool for systematics studies which is sufficiently realistic and highly controllable.« less

  2. Modeling the Transfer Function for the Dark Energy Survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chang, C.; Busha, M. T.; Wechsler, R. H.; Refregier, A.; Amara, A.; Rykoff, E.; Becker, M. R.; Bruderer, C.; Gamper, L.; Leistedt, B.; Peiris, H.; Abbott, T.; Abdalla, F. B.; Balbinot, E.; Banerji, M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Carnero, A.; Desai, S.; da Costa, L. N.; Cunha, C. E; Eifler, T.; Evrard, A. E.; Fausti Neto, A.; Gerdes, D.; Gruen, D.; James, D.; Kuehn, K.; Maia, M. A. G.; Makler, M.; Ogando, R.; Plazas, A.; Sanchez, E.; Santiago, B.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, C.; Soares-Santos, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Zuntz, J.

    2015-03-10

    We present a forward-modelling simulation framework designed to model the data products from the Dark Energy Survey (DES). This forward-model process can be thought of as a transfer function -- a mapping from cosmological and astronomical signals to the final data products used by the scientists. Using output from the cosmological simulations (the Blind Cosmology Challenge), we generate simulated images (the Ultra Fast Image Simulator, Berge et al. 2013) and catalogs representative of the DES data. In this work we simulate the 244 deg2 coadd images and catalogs in 5 bands for the DES Science Verification (SV) data. The simulation output is compared with the corresponding data to show that major characteristics of the images and catalogs can be captured. We also point out several directions of future improvements. Two practical examples, star/galaxy classification and proximity effects on object detection, are then used to demonstrate how one can use the simulations to address systematics issues in data analysis. With clear understanding of the simplifications in our model, we show that one can use the simulations side-by-side with data products to interpret the measurements. This forward modelling approach is generally applicable for other upcoming and future surveys. It provides a powerful tool for systematics studies which is sufficiently realistic and highly controllable.

  3. Automated Transient Identification in the Dark Energy Survey

    E-Print Network [OSTI]

    Goldstein, D A; Fischer, J A; Foley, R J; Gupta, R R; Kessler, R; Kim, A G; Nichol, R C; Nugent, P; Papadopoulos, A; Sako, M; Smith, M; Sullivan, M; Thomas, R C; Wester, W; Wolf, R C; Abdalla, F B; Banerji, M; Benoit-Lévy, A; Bertin, E; Brooks, D; Rosell, A Carnero; Castander, F J; da Costa, L N; Covarrubias, R; DePoy, D L; Desai, S; Diehl, H T; Doel, P; Eifler, T F; Neto, A Fausti; Finley, D A; Flaugher, B; Fosalba, P; Frieman, J; Gerdes, D; Gruen, D; Gruendl, R A; James, D; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; Maia, M A G; Makler, M; March, M; Marshall, J L; Martini, P; Merritt, K W; Miquel, R; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Walker, A R

    2015-01-01

    We describe an algorithm for identifying point-source transients and moving objects on reference-subtracted optical images containing artifacts of processing and instrumentation. The algorithm makes use of the supervised machine learning technique known as Random Forest. We present results from its use in the Dark Energy Survey Supernova program (DES-SN), where it was trained using a sample of 898,963 signal and background events generated by the transient detection pipeline. After reprocessing the data collected during the first DES-SN observing season (Sep. 2013 through Feb. 2014) using the algorithm, the number of transient candidates eligible for human scanning decreased by a factor of 13.4, while only 1 percent of the artificial Type Ia supernovae (SNe) injected into search images to monitor survey efficiency were lost, most of which were very faint events. Here we characterize the algorithm's performance in detail, and we discuss how it can inform pipeline design decisions for future time-domain imaging...

  4. Optimizing future imaging survey of galaxies to confront dark energy and modified gravity models

    E-Print Network [OSTI]

    Kazuhiro Yamamoto; David Parkinson; Takashi Hamana; Robert C. Nichol; Yasushi Suto

    2007-07-22

    We consider the extent to which future imaging surveys of galaxies can distinguish between dark energy and modified gravity models for the origin of the cosmic acceleration. Dynamical dark energy models may have similar expansion rates as models of modified gravity, yet predict different growth of structure histories. We parameterize the cosmic expansion by the two parameters, $w_0$ and $w_a$, and the linear growth rate of density fluctuations by Linder's $\\gamma$, independently. Dark energy models generically predict $\\gamma \\approx 0.55$, while the DGP model $\\gamma \\approx 0.68$. To determine if future imaging surveys can constrain $\\gamma$ within 20 percent (or $\\Delta\\gammafuture CMB observations.

  5. Covariance of dark energy parameters and sound speed constraints from large HI surveys

    E-Print Network [OSTI]

    A. Torres-Rodriguez; C. M. Cress; K. Moodley

    2008-04-15

    An interesting probe of the nature of dark energy is the measure of its sound speed, $c_s$. We review the significance for constraining sound speed models of dark energy using large neutral hydrogen (HI) surveys with the Square Kilometre Array (SKA). Our analysis considers the effect on the sound speed measurement that arises from the covariance of $c_s$ with the dark energy density, $\\Omega_\\LLambda$, and a time-varying equation of state, $w(a)=w_0+(1-a)w_a$. We find that the approximate degeneracy between dark energy parameters that arises in power spectrum observations is lifted through redshift tomography of the HI-galaxy angular power spectrum, resulting in sound speed constraints that are not severely degraded. The cross-correlation of the galaxy and the integrated Sachs-Wolfe (ISW) effect spectra contributes approximately 10 percent of the information that is needed to distinguish variations in the dark energy parameters, and most of the discriminating signal comes from the galaxy auto-correlation spectrum. We also find that the sound speed constraints are weakly sensitive to the HI bias model. These constraints do not improve substantially for a significantly deeper HI survey since most of the clustering sensitivity to sound speed variations arises from $z \\lsim 1.5$. A detection of models with sound speeds close to zero, $c_s \\lsim 0.01,$ is possible for dark energy models with $w\\gsim -0.9$.

  6. Constraints on perfect fluid and scalar field dark energy models from future redshift surveys

    E-Print Network [OSTI]

    Luca Amendola; Claudia Quercellini; Emanuele Giallongo

    2004-05-02

    We discuss the constraints that future photometric and spectroscopic redshift surveys can put on dark energy through the baryon oscillations of the power spectrum. We model the dark energy either with a perfect fluid or a scalar field and take into account the information contained in the linear growth function. We show that the growth function helps to break the degeneracy in the dark energy parameters and reduce the errors on $w_0,w_1$ roughly by 30% making more appealing multicolor surveys based on photometric redshifts. We find that a 200 square degrees spectroscopic survey reaching $z = 3$ can constrain $w_0,w_1$ to within $\\Delta w_0=0.21,\\Delta w_1=0.26$ and to $\\Delta w_0=0.39,\\Delta w_1=0.54$ using photometric redshifts with absolute uncertainty of 0.02. In the scalar field case we show that the slope $n$ of the inverse power-law potential for dark energy can be constrained to $\\Delta n=0.26$ (spectroscopic redshifts) or $\\Delta n=0.40$ (photometric redshifts), i.e. better than with future ground-based supernovae surveys or CMB data.

  7. TRACKING THE EVOLUTION OF LUMINOUS RED GALAXIES USING THE DARK ENERGY SURVEY 

    E-Print Network [OSTI]

    Mondrik, Nicholas P

    2014-09-22

    in this thesis an analysis of the mass and color evolution (from $z=0.1$ to $z=1$) of a subset of galaxies called luminous red galaxies (LRGs) taken from the Dark Energy Survey. LRGs are the most massive galaxies found in the nearby universe, and typically...

  8. Probing dark energy with baryonic oscillations and future radio surveys of neutral Hydrogen

    E-Print Network [OSTI]

    F. B. Abdalla; S. Rawlings

    2004-11-12

    Current surveys may be on the verge of measuring the baryonic oscillations in the galaxy power spectrum which are clearly seen imprinted on the Cosmic Microwave Background. It has recently been proposed that these oscillations allow a `standard ruler' method of probing the equation of state of dark energy. In this paper we present a new calculation of the number of galaxies future adio telescopes will detect in surveys of the sky in neutral Hydrogen (HI). We estimate the likely statistical errors if the standard ruler method were to be applied to such surveys. We emphasise uncertainties in our calculations, and pinpoint the most important features of future HI surveys if they are to provide new constraints on dark energy via baryonic oscillations. Designs of future radio telescopes are required to have a large bandwidth (characterised by \\beta$, the ratio of the instantaneous bandwidth to the bandwidth required by survey) and to have the widest instantaneous (1.4 GHz) field of view ($FOV$) possible. Given the expected sensitivity of a future Square Kilometre Array (SKA), given that half of its collecting area will be concentrated in a core of diameter $\\sim 5 ~ \\rm km$, and given a reasonable survey duration ($T_0$ $\\sim$ 1 yr), we show that there will be negligible shot noise on a power spectrum derived from HI galaxies out to redshift $z \\simeq 1.5$. To access the largest cosmic volume possible by surveying all the sky available, we argue that $\\beta$, $T_0$ and $FOV$ must obey the relation $\\beta FOV T_0 \\gtsimeq 10 \\rm deg^2$ yr. An $\\sim$1-yr SKA survey would then contain $\\gtsimeq 10^{9} (f_{\\rm sky}/0.5)$ HI galaxies and provide constraints on the dark-energy parameter $w$ of order $\\Delta w \\simeq 0.01 (f_{\\rm sky}/0.5)^{-0.5}$.

  9. Utilizing Type Ia Supernovae in a Large, Fast, Imaging Survey to Constrain Dark Energy

    E-Print Network [OSTI]

    Andrew R. Zentner; Suman Bhattacharya

    2008-12-01

    We study the utility of a large sample of type Ia supernovae that might be observed in an imaging survey that rapidly scans a large fraction of the sky for constraining dark energy. We consider information from the traditional luminosity distance test as well as the spread in SNeIa fluxes at fixed redshift induced by gravitational lensing. We include a treatment of photometric redshift uncertainties in our analysis. Our primary result is that the information contained in the mean distance moduli of SNeIa and the dispersion among SNeIa distance moduli complement each other, breaking a degeneracy between the present dark energy equation of state and its time variation without the need for a high-redshift supernova sample. To address photometric redshift uncertainties, we present dark energy constraints as a function of the size of an external set of spectroscopically-observed SNeIa that may be used for redshift calibration, nspec. We find that an imaging survey can constrain the dark energy equation of state at the epoch where it is best constrained with a 1-sigma error of sigma(wpiv)~0.03-0.09$, depending upon various assumptions. In addition, the marginal improvement in the error sigma(wpiv) from an increase in the spectroscopic calibration sample drops once nspec ~ 10^3. This result is important because it is of the order of the size of calibration samples likely to be compiled in the coming decade and because, for samples of this size, the spectroscopic and imaging surveys individually place comparable constraints on the dark energy equation of state. In all cases, it is best to calibrate photometric redshifts with a set of spectroscopically-observed SNeIa with relatively more objects at high redshift than the parent sample of imaging SNeIa.

  10. No galaxy left behind: accurate measurements with the faintest objects in the Dark Energy Survey

    E-Print Network [OSTI]

    Suchyta, E; Aleksi?, J; Melchior, P; Jouvel, S; MacCrann, N; Crocce, M; Gaztanaga, E; Honscheid, K; Leistedt, B; Peiris, H V; Ross, A J; Rykoff, E S; Sheldon, E; Abbott, T; Abdalla, F B; Allam, S; Banerji, M; Benoit-Lévy, A; Bertin, E; Brooks, D; Burke, D L; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Cunha, C E; D'Andrea, C B; da Costa, L N; DePoy, D L; Desai, S; Diehl, H T; Dietrich, J P; Doel, P; Eifler, T F; Estrada, J; Evrard, A E; Flaugher, B; Fosalba, P; Frieman, J; Gerdes, D W; Gruen, D; Gruendl, R A; James, D J; Jarvis, M; Kuehn, K; Kuropatkin, N; Lahav, O; Lima, M; Maia, M A G; March, M; Marshall, J L; Miller, C J; Miquel, R; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Percival, W J; Reil, K; Roodman, A; Sako, M; Sanchez, E; Scarpine, V; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Swanson, M E C; Tarle, G; Thaler, J; Thomas, D; Vikram, V; Walker, A R; Wechsler, R H; Zhang, Y

    2015-01-01

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of stars or galaxies detectable in an imaging survey. We have implemented our proposal in Balrog, a software package which embeds fake objects in real imaging in order to accurately characterize measurement biases. We demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a wide variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for th...

  11. Observation of Two New L4 Neptune Trojans in the Dark Energy Survey Supernova Fields

    E-Print Network [OSTI]

    Gerdes, D W; Bernstein, G M; Sako, M; Adams, F; Goldstein, D; Kessler, R; Abbott, T; Abdalla, F B; Allam, S; Benoit-Lévy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Capozzi, D; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Cunha, C E; D'Andrea, C B; da Costa, L N; DePoy, D L; Desai, S; Dietrich, J P; Doel, P; Eifler, T F; Neto, A Fausti; Flaugher, B; Frieman, J; Gaztanaga, E; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; Maia, M A G; March, M; Martini, P; Miller, C J; Miquel, R; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sanchez, E; Santiago, B; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarlé, G; Thaler, J; Walker, A R; Wester, W; Zhang, Y

    2015-01-01

    We report the discovery of the eighth and ninth known Trojans in stable orbits around Neptune's leading Lagrange point, L4. The objects 2014 QO$_{441}$ and 2014 QP$_{441}$ were detected in data obtained during the 2013-14 and 2014-15 observing seasons by the Dark Energy Survey, using the Dark Energy Camera (DECam) on the 4-meter Blanco telescope at Cerro Tololo Inter-American Observatory. Both are in high-inclination orbits (18.8$^{\\circ}$ and 19.4$^{\\circ}$ respectively). With an eccentricity of 0.104, 2014 QO$_{441}$ has the most eccentric orbit of the eleven known stable Neptune Trojans. Here we describe the search procedure and investigate the objects' long-term dynamical stability and physical properties.

  12. The Mira-Titan Universe: Precision Predictions for Dark Energy Surveys

    E-Print Network [OSTI]

    Heitmann, Katrin; Lawrence, Earl; Bergner, Steven; Habib, Salman; Higdon, David; Pope, Adrian; Biswas, Rahul; Finkel, Hal; Frontiere, Nicholas; Bhattacharya, Suman

    2015-01-01

    Ground and space-based sky surveys enable powerful cosmological probes based on measurements of galaxy properties and the distribution of galaxies in the Universe. These probes include weak lensing, baryon acoustic oscillations, abundance of galaxy clusters, and redshift space distortions; they are essential to improving our knowledge of the nature of dark energy. On the theory and modeling front, large-scale simulations of cosmic structure formation play an important role in interpreting the observations and in the challenging task of extracting cosmological physics at the needed precision. These simulations must cover a parameter range beyond the standard six cosmological parameters and need to be run at high mass and force resolution. One key simulation-based task is the generation of accurate theoretical predictions for observables, via the method of emulation. Using a new sampling technique, we explore an 8-dimensional parameter space including massive neutrinos and a variable dark energy equation of sta...

  13. Observation of Two New L4 Neptune Trojans in the Dark Energy Survey Supernova Fields

    SciTech Connect (OSTI)

    Gerdes, D. W.

    2015-07-18

    We report the discovery of the eighth and ninth known Trojans in stable orbits around Neptune's leading Lagrange point, L4. The objects 2014 QO441 and 2014 QP441 were detected in data obtained during the 2013-14 and 2014-15 observing seasons by the Dark Energy Survey, using the Dark Energy Camera (DECam) on the 4-meter Blanco telescope at Cerro Tololo Inter- American Observatory. Both are in high-inclination orbits (18.8° and 19.4° respectively). Furthermore, with an eccentricity of 0.104, 2014 QO441 has the most eccentric orbit of the eleven known stable Neptune Trojans. We describe the search procedure and investigate the objects' long-term dynamical stability and physical properties.

  14. Dark Energy Probes of Dark Energy

    E-Print Network [OSTI]

    Weijgaert, Rien van de

    19/12/2013 1 Dark Energy Probes of Dark Energy Probes Dark Energy Supernovae Ia probing luminosity (Betti numbers) #12;19/12/2013 2 Dark Energy Probes: Comparison Method Strengths Weaknesses Systematics

  15. dark matter dark energy inflation

    E-Print Network [OSTI]

    Hu, Wayne

    theory dark matter dark energy inflation The National Science Foundation The Kavli Foundation NSF Site Review November 28-29, 2005 #12;dark matter dark energy inflation NSF Site Visit ­ November 28 - 29, 2005The National Science Foundation The Kavli Foundation The Theoretical Web UHE cosmic rays B

  16. Wide-Field Lensing Mass Maps from Dark Energy Survey Science Verification Data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chang, C.

    2015-07-29

    We present a mass map reconstructed from weak gravitational lensing shear measurements over 139 deg2 from the Dark Energy Survey science verification data. The mass map probes both luminous and dark matter, thus providing a tool for studying cosmology. We also find good agreement between the mass map and the distribution of massive galaxy clusters identified using a red-sequence cluster finder. Potential candidates for superclusters and voids are identified using these maps. We measure the cross-correlation between the mass map and a magnitude-limited foreground galaxy sample and find a detection at the 6.8? level with 20 arc min smoothing. Thesemore »measurements are consistent with simulated galaxy catalogs based on N-body simulations from a cold dark matter model with a cosmological constant. This suggests low systematics uncertainties in the map. Finally, we summarize our key findings in this Letter; the detailed methodology and tests for systematics are presented in a companion paper.« less

  17. Cyber-infrastructure to Support Science and Data Management for the Dark Energy Survey

    E-Print Network [OSTI]

    C. Ngeow; J. J. Mohr; T. Alam; W. A. Barkhouse; C. Beldica; D. Cai; G. Daues; R. Plante; J. Annis; H. Lin; D. Tucker; R. C. Smith

    2006-08-11

    The Dark Energy Survey (DES; operations 2009-2015) will address the nature of dark energy using four independent and complementary techniques: (1) a galaxy cluster survey over 4000 deg2 in collaboration with the South Pole Telescope Sunyaev-Zel'dovich effect mapping experiment, (2) a cosmic shear measurement over 5000 deg2, (3) a galaxy angular clustering measurement within redshift shells to redshift=1.35, and (4) distance measurements to 1900 supernovae Ia. The DES will produce 200 TB of raw data in four bands, These data will be processed into science ready images and catalogs and co-added into deeper, higher quality images and catalogs. In total, the DES dataset will exceed 1 PB, including a 100 TB catalog database that will serve as a key science analysis tool for the astronomy/cosmology community. The data rate, volume, and duration of the survey require a new type of data management (DM) system that (1) offers a high degree of automation and robustness and (2) leverages the existing high performance computing infrastructure to meet the project's DM targets. The DES DM system consists of (1) a grid-enabled, flexible and scalable middleware developed at NCSA for the broader scientific community, (2) astronomy modules that build upon community software, and (3) a DES archive to support automated processing and to serve DES catalogs and images to the collaboration and the public. In the recent DES Data Challenge 1 we deployed and tested the first version of the DES DM system, successfully reducing 700 GB of raw simulated images into 5 TB of reduced data products and cataloguing 50 million objects with calibrated astrometry and photometry.

  18. The Difference Imaging Pipeline for the Transient Search in the Dark Energy Survey

    E-Print Network [OSTI]

    Kessler, R; Childress, M; Covarrubias, R; D'Andrea, C B; Finley, D A; Fischer, J; Foley, R J; Goldstein, D; Gupta, R R; Kuehn, K; Marcha, M; Nichol, R C; Papadopoulos, A; Sako, M; Scolnic, D; Smith, M; Sullivan, M; Wester, W; Yuan, F; Abbott, T; Abdalla, F B; Allam, S; Benoit-Levy, A; Bernstein, G M; Bertin, E; Brooks, D; Rosell, A Carnero; Kind, M Carrasco; Castander, F J; Crocce, M; da Costa, L N; Desai, S; Diehl, H T; Eifler, T F; Neto, A Fausti; Flaugher, B; Frieman, J; Gruen, D; Gruendl, R A; Honscheid, K; James, D J; Kuropatkin, N; Li, T S; Maia, M A G; Marshall, J L; Martini, P; Miller, C J; Miquel, R; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sanchez, E; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Tarle, G; Thaler, J; Thomas, R C; Tucker, D; Walker, A R

    2015-01-01

    We describe the difference imaging pipeline (DiffImg) used to detect transients in deep images from the Dark Energy Survey Supernova program (DES-SN) in its first observing season from Aug 2013 through Feb 2014. DES-SN is a search for transients in which ten 3-deg^2 fields are repeatedly observed in the g,r,i,z passbands with a cadence of about 1 week. The observing strategy has been optimized to measure high-quality light curves and redshifts for thousands of Type Ia supernova (SN Ia) with the goal of measuring dark energy parameters. The essential DiffImg functions are to align each search image to a deep reference image, do a pixel-by-pixel subtraction, and then examine the subtracted image for significant positive detections of point-source objects. The vast majority of detections are subtraction artifacts, but after selection requirements and image filtering with an automated scanning program, there are 130 detections per deg^2 per observation in each band, of which only 25% are artifacts. Of the 7500 tr...

  19. DESAlert: Enabling Real-Time Transient Follow-Up with Dark Energy Survey Data

    E-Print Network [OSTI]

    Poci, A; :,; Abbott, T; Abdalla, F B; Allam, S; Bauer, A H; Benoit-Lévy, A; Bertin, E; Brooks, D; Brown, P J; Buckley-Geer, E; Burke, D L; Rosell, A Carnero; Kind, M Carrasco; Covarrubias, R; da Costa, L N; D'Andrea, C B; DePoy, D L; Desai, S; Dietrich, J P; Cunha, C E; Eifler, T F; Estrada, J; Evrard, A E; Neto, A Fausti; Finley, D A; Flaugher, B; Fosalba, P; Frieman, J; Gerdes, D; Gruen, D; Gruendl, R A; Honscheid, K; James, D; Kuropatkin, N; Lahav, O; Li, T S; March, M; Marshall, J; Merritt, K W; Miller, C J; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Rykoff, E S; Sako, M; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla, I; Smith, C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Thomas, R C; Tucker, D; Walker, A R; Wester, W

    2015-01-01

    The Dark Energy Survey (DES) is currently undertaking an observational program imaging $1/4$ of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the DES will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts (GRBs) over five years. Once GRBs are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automated notices of GRB activity, collates useful information from archival DES data, and promulgates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that DES data provide for relative photometry of GRBs or their afterglows, as well as for identifying key characteristics (e.g., photometric redshi...

  20. Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Drlica-Wagner, A.

    2015-11-04

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two lower-confidence candidates are identified in regions of non-uniform survey coverage. The new stellar systems are found by three independent automated search techniques and are identified as overdensities of stars, consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (MV > -4.7 ) and span a range of physical sizes (17 pc 1/2more »pc) and heliocentric distances (25 kpc ? mag arcsec -2). Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies. Most of the candidates are found in the southern part of the DES footprint close to the Magellanic Clouds. We find that the DES data alone exclude (p -3) a spatially isotropic distribution of Milky Way satellites and that the observed distribution can be well, though not uniquely, described by an association between several of the DES satellites and the Magellanic system. Our model predicts that the full sky may hold ~100 ultra-faint galaxies with physical properties comparable to the DES satellites and that 20%–30% of these would be spatially associated with the Magellanic Clouds.« less

  1. Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey

    E-Print Network [OSTI]

    Drlica-Wagner, A; Rykoff, E S; Luque, E; Queiroz, A; Mao, Y -Y; Wechsler, R H; Simon, J D; Santiago, B; Yanny, B; Balbinot, E; Dodelson, S; Neto, A Fausti; James, D J; Li, T S; Maia, M A G; Marshall, J L; Pieres, A; Stringer, K; Walker, A R; Abbott, T M C; Abdalla, F B; Allam, S; Benoit-Levy, A; Bernstein, G M; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; da Costa, L N; Desai, S; Diehl, H T; Dietrich, J P; Doel, P; Eifler, T F; Evrard, A E; Finley, D A; Fosalba, P; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; Kuehn, K; Kuropatkin, N; Lahav, O; Martini, P; Miquel, R; Nord, B; Ogando, R; Plazas, A A; Reil, K; Roodman, A; Sako, M; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Tucker, D; Vikram, V; Wester, W; Zhang, Y; Zuntz, J

    2015-01-01

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two additional lower-confidence candidates are identified in regions of incomplete or non-uniform survey coverage. The new stellar systems are found using three independent automated search techniques, and are identified as statistically significant overdensities of individually resolved stars consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (Mv > -4.7 mag) and span a broad range of physical sizes (17 pc 27.5 mag arcsec$^2$) consistent with known ultra-faint dwarf galaxies. Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies, and would have had a low probability of detection if observed by the Sloan Digital Sky S...

  2. Discovery of two gravitationally lensed quasars in the Dark Energy Survey

    E-Print Network [OSTI]

    Agnello, Adriano; Ostrovski, Fernanda; Schechter, Paul L; Buckley-Geer, Elizabeth J; Lin, Huan; Auger, Matthew W; Courbin, Frederic; Fassnacht, Christopher D; Frieman, Josh; Kuropatkin, Nikolay; Marshall, Philip J; McMahon, Richard G; Meylan, Georges; More, Anupreeta; Suyu, Sherry H; Rusu, Cristian E; Finley, David; Abbott, Tim; Abdalla, Filipe B; Allam, Sahar; Annis, James; Banerji, Manda; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, David; Burke, David L; Rosell, Aurelio Carnero; Kind, Matias Carrasco; Carretero, Jorge; Cunha, Carlos E; D'Andrea, Chris B; da Costa, Luiz N; Desai, Shantanu; Diehl, H Thomas; Dietrich, Jörg P; Doel, Peter; Eifler, Tim F; Estrada, Juan; Neto, Angelo Fausti; Flaugher, Brenna; Fosalba, Pablo; Gerdes, David W; Gruen, Daniel; Gutierrez, Gaston; Honscheid, Klaus; James, David J; Kuehn, Kyler; Lahav, Ofer; Lima, Marco; Maia, Marcio A G; March, Marina; Marshall, Jennifer L; Martini, Paul; Melchior, Peter; Miller, Christopher J; Miquel, Ramon; Nichol, Robert C; Ogando, Ricardo; Plazas, Andres A; Reil, Kevin; Romer, A Kathy; Roodman, Aaron; Sako, Masao; Sanchez, Eusebio; Santiago, Basilio; Scarpine, Vic; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Smith, R Chris; Soares-Santos, Marcelle; Sobreira, Flavia; Suchyta, Eric; Swanson, Molly E C; Tarle, Gregory; Thaler, Jon; Tucker, Douglas; Walker, Alistair R; Wechsler, Risa H; Zhang, Yuanyuan

    2015-01-01

    We present spectroscopic confirmation of two new lensed quasars via data obtained at the 6.5m Magellan/Baade Telescope. The lens candidates have been selected from the Dark Energy Survey (DES) and WISE based on their multi-band photometry and extended morphology in DES images. Images of DES J0115-5244 show two blue point sources at either side of a red galaxy. Our long-slit data confirm that both point sources are images of the same quasar at $z_{s}=1.64.$ The Einstein Radius estimated from the DES images is $0.51$". DES J2200+0110 is in the area of overlap between DES and the Sloan Digital Sky Survey (SDSS). Two blue components are visible in the DES and SDSS images. The SDSS fiber spectrum shows a quasar component at $z_{s}=2.38$ and absorption compatible with Mg II and Fe II at $z_{l}=0.799$, which we tentatively associate with the foreground lens galaxy. The long-slit Magellan spectra show that the blue components are resolved images of the same quasar. The Einstein Radius is $0.68$" corresponding to an e...

  3. Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey

    E-Print Network [OSTI]

    The DES Collaboration; A. Drlica-Wagner; K. Bechtol; E. S. Rykoff; E. Luque; A. Queiroz; Y. -Y. Mao; R. H. Wechsler; J. D. Simon; B. Santiago; B. Yanny; E. Balbinot; S. Dodelson; A. Fausti Neto; D. J. James; T. S. Li; M. A. G. Maia; J. L. Marshall; A. Pieres; K. Stringer; A. R. Walker; T. M. C. Abbott; F. B. Abdalla; S. Allam; A. Benoit-Levy; G. M. Bernstein; E. Bertin; D. Brooks; E. Buckley-Geer; D. L. Burke; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; M. Crocce; L. N. da Costa; S. Desai; H. T. Diehl; J. P. Dietrich; P. Doel; T. F. Eifler; A. E. Evrard; D. A. Finley; P. Fosalba; J. Frieman; E. Gaztanaga; D. W. Gerdes; D. Gruen; R. A. Gruendl; G. Gutierrez; K. Honscheid; K. Kuehn; N. Kuropatkin; O. Lahav; P. Martini; R. Miquel; B. Nord; R. Ogando; A. A. Plazas; K. Reil; A. Roodman; M. Sako; E. Sanchez; V. Scarpine; M. Schubnell; I. Sevilla-Noarbe; R. C. Smith; M. Soares-Santos; F. Sobreira; E. Suchyta; M. E. C. Swanson; G. Tarle; D. Tucker; V. Vikram; W. Wester; Y. Zhang; J. Zuntz

    2015-08-14

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two additional lower-confidence candidates are identified in regions of incomplete or non-uniform survey coverage. The new stellar systems are found using three independent automated search techniques, and are identified as statistically significant overdensities of individually resolved stars consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (Mv > -4.7 mag) and span a broad range of physical sizes (17 pc 27.5 mag arcsec$^2$) consistent with known ultra-faint dwarf galaxies. Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies, and would have had a low probability of detection if observed by the Sloan Digital Sky Survey. A large fraction of satellite candidates are found in the southern half of the DES footprint in proximity to the Magellanic Clouds. We find that the DES data alone exclude (p < 0.001) a spatially isotropic distribution of Milky Way satellites, and that this distribution can be well, although not uniquely, explained by a model in which several of the observed DES satellites are associated with the Magellanic system. Including the current sample, our model predicts that ~100 ultra-faint galaxies with physical properties comparable to the DES satellites might exist over the full sky and that 20-30% of these would be spatially associated with the Magellanic Clouds.

  4. Dark energy without dark energy

    E-Print Network [OSTI]

    Pedro F. Gonzalez-Diaz

    2006-08-29

    It is proposed that the current acceleration of the universe is not originated by the existence of a mysterious dark energy fluid nor by the action of extra terms in the gravity Lagrangian, but just from the sub-quantum potential associated with the CMB particles. The resulting cosmic scenario corresponds to a benigner phantom model which is free from the main problems of the current phantom approaches.

  5. Observation and Confirmation of Six Strong Lensing Systems in The Dark Energy Survey Science Verification Data

    E-Print Network [OSTI]

    Nord, B; Lin, H; Diehl, H T; Helsby, J; Kuropatkin, N; Amara, A; Collett, T; Allam, S; Caminha, G; De Bom, C; Desai, S; Dúmet-Montoya, H; Pereira, M Elidaiana da S; Finley, D A; Flaugher, B; Furlanetto, C; Gaitsch, H; Gill, M; Merritt, K W; More, A; Tucker, D; Rykoff, E S; Rozo, E; Abdalla, F B; Agnello, A; Auger, M; Brunner, R J; Kind, M Carrasco; Castander, F J; Cunha, C E; da Costa, L N; Foley, R; Gerdes, D W; Glazebrook, K; Gschwend, J; Hartley, W; Kessler, R; Lagattuta, D; Lewis, G; Maia, M A G; Makler, M; Menanteau, F; Niernberg, A; Scolnic, D; Vieira, J D; Gramillano, R; Abbott, T M C; Banerji, M; Benoit-Lévy, A; Brooks, D; Burke, D L; Capozzi, D; Rosell, A Carnero; Carretero, J; D'Andrea, C B; Dietrich, J P; Doel, P; Evrard, A E; Frieman, J; Gaztanaga, E; Gruen, D; Honscheid, K; James, D J; Kuehn, K; Li, T S; Lima, M; Marshall, J L; Martini, P; Melchior, P; Miquel, R; Neilsen, E; Nichol, R C; Ogando, R; Plazas, A A; Romer, A K; Sako, M; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Walker, A R; Wester, W; Zhang, Y

    2015-01-01

    We report the observation and confirmation of the first group- and cluster-scale strong gravitational lensing systems found in Dark Energy Survey (DES) data. Through visual inspection of data from the Science Verification (SV) season, we identified 53 candidate systems. We then obtained spectroscopic follow-up of 21 candidates using the Gemini Multi-Object Spectrograph (GMOS) at the Gemini South telescope and the Inamori-Magellan Areal Camera and Spectrograph (IMACS) at the Magellan/Baade telescope. With this follow-up, we confirmed six candidates as gravitational lenses: Three of the systems are newly discovered, and the remaining three were previously known. Of the 21 observed candidates, the remaining 15 were either not detected in spectroscopic observations, were observed and did not exhibit continuum emission (or spectral features), or were ruled out as lensing systems. The confirmed sample consists of one group-scale and five galaxy cluster-scale lenses. The lensed sources range in redshift z ~ 0.80-3.2...

  6. Discovery of a Stellar Overdensity in Eridanus-Phoenix in the Dark Energy Survey

    E-Print Network [OSTI]

    Li, T S; Mondrik, N; Marshall, J L; Yanny, B; Bechtol, K; Drlica-Wagner, A; Oscar, D; Santiago, B; Simon, J D; Vivas, A K; Walker, A R; Wang, M Y; Abbott, T M C; Abdalla, F B; Benoit-Lévy, A; Bernstein, G M; Bertin, E; Brooks, D; Burke, D L; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; da Costa, L N; DePoy, D L; Desai, S; Diehl, H T; Doel, P; Estrada, J; Finley, D A; Flaugher, B; Frieman, J; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Kuropatkin, N; Lahav, O; Maia, M A G; March, M; Martini, P; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Tucker, D; Zhang, Y

    2015-01-01

    We report the discovery of an excess of main sequence turn-off stars in the direction of the constellations of Eridanus and Phoenix from the first year data of the Dark Energy Survey (DES). The Eridanus-Phoenix (EriPhe) overdensity is centered around l~285 deg and b~-60 deg and spans at least 30 deg in longitude and 10 deg in latitude. The Poisson significance of the detection is at least 9 sigma. The stellar population in the overdense region is similar in brightness and color to that of the nearby globular cluster NGC 1261, indicating that the heliocentric distance of EriPhe is about d~16 kpc. The extent of EriPhe in projection is therefore at least ~4 kpc by ~3 kpc. On the sky, this overdensity is located between NGC 1261 and a new stellar stream discovered by DES at a similar heliocentric distance, the so-called Phoenix Stream. Given their similar distance and proximity to each other, it is possible that these three structures may be kinematically associated. Alternatively, the EriPhe overdensity is morph...

  7. Discovery of Two Gravitationally Lensed Quasars in the Dark Energy Survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Agnello, A.

    2015-08-05

    We present spectroscopic confirmation of two new lensed quasars via data obtained at the 6.5m Magellan/Baade Telescope. The lens candidates have been selected from the Dark Energy Survey (DES) and WISE based on their multi-band photometry and extended morphology in DES images. Images of DES J0115-5244 show two blue point sources at either side of a red galaxy. Our long-slit data confirm that both point sources are images of the same quasar at zs = 1.64. The Einstein Radius estimated from the DES images is 0.51'' . DES J2146-0047 is in the area of overlap between DES and the Sloanmore »Digital Sky Survey (SDSS). Two blue components are visible in the DES and SDSS images. The SDSS fiber spectrum shows a quasar component at zs = 2.38 and absorption compatible with Mg II and Fe II at zl = 0.799, which we tentatively associate with the foreground lens galaxy. The long-slit Magellan spectra show that the blue components are resolved images of the same quasar. Furthermore, the Einstein Radius is 0.68'' corresponding to an enclosed mass of 1.6 × 1011 M?. Three other candidates were observed and rejected, two being low-redshift pairs of starburst galaxies, and one being a quasar behind a blue star. These first confirmation results provide an important empirical validation of the data-mining and model-based selection that is being applied to the entire DES dataset.« less

  8. Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey

    E-Print Network [OSTI]

    The DES Collaboration; A. Drlica-Wagner; K. Bechtol; E. S. Rykoff; E. Luque; A. Queiroz; Y. -Y. Mao; R. H. Wechsler; J. D. Simon; B. Santiago; B. Yanny; E. Balbinot; S. Dodelson; A. Fausti Neto; D. J. James; T. S. Li; M. A. G. Maia; J. L. Marshall; A. Pieres; K. Stringer; A. R. Walker; T. M. C. Abbott; F. B. Abdalla; S. Allam; A. Benoit-Levy; G. M. Bernstein; E. Bertin; D. Brooks; E. Buckley-Geer; D. L. Burke; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; M. Crocce; L. N. da Costa; S. Desai; H. T. Diehl; J. P. Dietrich; P. Doel; T. F. Eifler; A. E. Evrard; D. A. Finley; B. Flaugher; P. Fosalba; J. Frieman; E. Gaztanaga; D. W. Gerdes; D. Gruen; R. A. Gruendl; G. Gutierrez; K. Honscheid; K. Kuehn; N. Kuropatkin; O. Lahav; P. Martini; R. Miquel; B. Nord; R. Ogando; A. A. Plazas; K. Reil; A. Roodman; M. Sako; E. Sanchez; V. Scarpine; M. Schubnell; I. Sevilla-Noarbe; R. C. Smith; M. Soares-Santos; F. Sobreira; E. Suchyta; M. E. C. Swanson; G. Tarle; D. Tucker; V. Vikram; W. Wester; Y. Zhang; J. Zuntz

    2015-11-06

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two lower-confidence candidates are identified in regions of non-uniform survey coverage. The new stellar systems are found by three independent automated search techniques and are identified as overdensities of stars, consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (Mv > -4.7 mag) and span a range of physical sizes (17 pc < $r_{1/2}$ < 181 pc) and heliocentric distances (25 kpc < D < 214 kpc). All of the new systems have central surface brightnesses consistent with known ultra-faint dwarf galaxies (\\mu < 27.5 mag arcsec$^{-2}$). Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies. Most of the candidates are found in the southern part of the DES footprint close to the Magellanic Clouds. We find that the DES data alone exclude (p < 0.001) a spatially isotropic distribution of Milky Way satellites and that the observed distribution can be well, though not uniquely, described by an association between several of the DES satellites and the Magellanic system. Our model predicts that the full sky may hold ~100 ultra-faint galaxies with physical properties comparable to the DES satellites and that 20-30% of these would be spatially associated with the Magellanic Clouds.

  9. The Difference Imaging Pipeline for the Transient Search in the Dark Energy Survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kessler, R.

    2015-09-09

    We describe the operation and performance of the difference imaging pipeline (DiffImg) used to detect transients in deep images from the Dark Energy Survey Supernova program (DES-SN) in its first observing season from 2013 August through 2014 February. DES-SN is a search for transients in which ten 3 deg2 fields are repeatedly observed in the g, r, i, zpassbands with a cadence of about 1 week. Our observing strategy has been optimized to measure high-quality light curves and redshifts for thousands of Type Ia supernovae (SNe Ia) with the goal of measuring dark energy parameters. The essential DiffImg functions aremore »to align each search image to a deep reference image, do a pixel-by-pixel subtraction, and then examine the subtracted image for significant positive detections of point-source objects. The vast majority of detections are subtraction artifacts, but after selection requirements and image filtering with an automated scanning program, there are ~130 detections per deg2 per observation in each band, of which only ~25% are artifacts. Of the ~7500 transients discovered by DES-SN in its first observing season, each requiring a detection on at least two separate nights, Monte Carlo (MC) simulations predict that 27% are expected to be SNe Ia or core-collapse SNe. Another ~30% of the transients are artifacts in which a small number of observations satisfy the selection criteria for a single-epoch detection. Spectroscopic analysis shows that most of the remaining transients are AGNs and variable stars. Fake SNe Ia are overlaid onto the images to rigorously evaluate detection efficiencies and to understand the DiffImg performance. Furthermore, the DiffImg efficiency measured with fake SNe agrees well with expectations from a MC simulation that uses analytical calculations of the fluxes and their uncertainties. In our 8 "shallow" fields with single-epoch 50% completeness depth ~23.5, the SN Ia efficiency falls to 1/2 at redshift z ? 0.7; in our 2 "deep" fields with mag-depth ~24.5, the efficiency falls to 1/2 at z ? 1.1. A remaining performance issue is that the measured fluxes have additional scatter (beyond Poisson fluctuations) that increases with the host galaxy surface brightness at the transient location. This bright-galaxy issue has minimal impact on the SNe Ia program, but it may lower the efficiency for finding fainter transients on bright galaxies.« less

  10. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Melchior, P.; Suchyta, E.; Huff, E.; Hirsch, M.; Kacprzak, T.; Rykoff, E.; Gruen, D.; Armstrong, R.; Bacon, D.; Bechtol, K.; et al

    2015-03-31

    We measure the weak-lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey. This pathfinder study is meant to 1) validate the DECam imager for the task of measuring weak-lensing shapes, and 2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, PSF modelling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Sciencemore »Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well-behaved, but the modelling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting NFW profiles to the clusters in this study, we determine weak-lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak-lensing mass, and richness. Additionally, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1degree (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.« less

  11. Weak Lensing: Dark Matter, Dark Energy

    SciTech Connect (OSTI)

    Jain, Bhuvnesh (University of Pennsylvania) [University of Pennsylvania

    2006-02-27

    The light rays from distant galaxies are deflected by massive structures along the line of sight, causing the galaxy images to be distorted. Measurements of these distortions, known as weak lensing, provide a way of measuring the distribution of dark matter as well as the spatial geometry of the universe. I will describe the ideas underlying this approach to cosmology. With planned large imaging surveys, weak lensing is a powerful probe of dark energy. I will discuss the observational challenges ahead and recent progress in developing multiple, complementary approaches to lensing measurements.

  12. DES13S2cmm: The first superluminous supernova from the dark energy survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Papadopoulos, A.; D'Andrea, C. B.; Sullivan, M.; Nichol, R. C.; Barbary, K.; Biswas, R.; Brown, P. J.; Covarrubias, R. A.; Finley, D. A.; Fischer, J. A.; et al

    2015-03-23

    We present DES13S2cmm, the first spectroscopically-confirmed superluminous supernova (SLSN) from the Dark Energy Survey (DES). We briefly discuss the data and search algorithm used to find this event in the first year of DES operations, and outline the spectroscopic data obtained from the European Southern Observatory (ESO) Very Large Telescope to confirm its redshift (z = 0.663 ± 0.001 based on the host-galaxy emission lines) and likely spectral type (type I). Using this redshift, we find MUpeak = -21.05???¹?-0.09 for the peak, rest-frame U-band absolute magnitude, and find DES13S2cmm to be located in a faint, low metallicity (sub-solar), low stellar-massmore »host galaxy (log(M/M_sun) = 9.3 ± 0.3); consistent with what is seen for other SLSNe-I. We compare the bolometric light curve of DES13S2cmm to fourteen similarly well-observed SLSNe-I in the literature and find it possesses one of the slowest declining tails (beyond +30 days rest frame past peak), and is the faintest at peak. Moreover, we find the bolometric light curves of all SLSNe-I studied herein possess a dispersion of only 0.2-0.3 magnitudes between +25 and +30 days after peak (rest frame) depending on redshift range studied; this could be important for 'standardising' such supernovae, as is done with the more common type Ia. We fit the bolometric light curve of DES13S2cmm with two competing models for SLSNe-I - the radioactive decay of ??Ni, and a magnetar - and find that while the magnetar is formally a better fit, neither model provides a compelling match to the data. Although we are unable to conclusively differentiate between these two physical models for this particular SLSN-I, further DES observations of more SLSNe-I should break this degeneracy, especially if the light curves of SLSNe-I can be observed beyond 100 days in the rest frame of the supernova.« less

  13. DES13S2cmm: The first superluminous supernova from the dark energy survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Papadopoulos, A. [Institute of Cosmology and Gravitation (ICG), Portsmouth (United Kingdom); D'Andrea, C. B.; Sullivan, M.; Nichol, R. C.; Barbary, K.; Biswas, R.; Brown, P. J.; Covarrubias, R. A.; Finley, D. A.; Fischer, J. A.; Foley, R. J.; Goldstein, D.; Gupta, R. R.; Kessler, R.; Kovacs, E.; Kuhlmann, S. E.; Lidman, C.; March, M.; Nugent, P. E.; Sako, M.; Smith, R. C.; Spinka, H.; Wester, W.; Abbott, T. M. C.; Abdalla, F.; Allam, S. S.; Banerji, M.; Bernstein, J. P.; Bernstein, R. A.; Carnero, A.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Eifler, T.; Evrard, A. E.; Flaugher, B.; Frieman, J. A.; Gerdes, D.; Gruen, D.; Honscheid, K.; James, D.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Maia, M. A. G.; Makler, M.; Marshall, J. L.; Merritt, K. W.; Miller, C. J.; Miquel, R.; Ogando, R.; Plazas, A. A.; Roe, N. A.; Romer, A. K.; Rykoff, E.; Sanchez, E.; Santiago, B. X.; Scarpine, V.; Schubnell, M.; Sevilla, I.; Soares-Santos, M.; Suchyta, E.; Swanson, M.; Tarle, G.; Thaler, J.; Tucker, L. D.; Wechsler, R. H.; Zuntz, J.

    2015-03-20

    We present DES13S2cmm, the first spectroscopically-confirmed superluminous supernova (SLSN) from the Dark Energy Survey (DES). We briefly discuss the data and search algorithm used to find this event in the first year of DES operations, and outline the spectroscopic data obtained from the European Southern Observatory (ESO) Very Large Telescope to confirm its redshift (z = 0.663 ± 0.001 based on the host-galaxy emission lines) and likely spectral type (type I). Using this redshift, we find MUpeak = -21.05???¹?-0.09 for the peak, rest-frame U-band absolute magnitude, and find DES13S2cmm to be located in a faint, low metallicity (sub-solar), low stellar-mass host galaxy (log(M/M_sun) = 9.3 ± 0.3); consistent with what is seen for other SLSNe-I. We compare the bolometric light curve of DES13S2cmm to fourteen similarly well-observed SLSNe-I in the literature and find it possesses one of the slowest declining tails (beyond +30 days rest frame past peak), and is the faintest at peak. Moreover, we find the bolometric light curves of all SLSNe-I studied herein possess a dispersion of only 0.2-0.3 magnitudes between +25 and +30 days after peak (rest frame) depending on redshift range studied; this could be important for 'standardising' such supernovae, as is done with the more common type Ia. We fit the bolometric light curve of DES13S2cmm with two competing models for SLSNe-I - the radioactive decay of ??Ni, and a magnetar - and find that while the magnetar is formally a better fit, neither model provides a compelling match to the data. Although we are unable to conclusively differentiate between these two physical models for this particular SLSN-I, further DES observations of more SLSNe-I should break this degeneracy, especially if the light curves of SLSNe-I can be observed beyond 100 days in the rest frame of the supernova.

  14. DES13S2cmm: The first superluminous supernova from the Dark Energy Survey

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Papadopoulos, A.; Plazas, A. A.; D"Andrea, C. B.; Sullivan, M.; Nichol, R. C.; Barbary, K.; Biswas, R.; Brown, P. J.; Covarrubias, R. A.; Finley, D. A.; et al

    2015-03-20

    We present DES13S2cmm, the first spectroscopically-confirmed superluminous supernova (SLSN) from the Dark Energy Survey (DES). We briefly discuss the data and search algorithm used to find this event in the first year of DES operations, and outline the spectroscopic data obtained from the European Southern Observatory (ESO) Very Large Telescope to confirm its redshift (z = 0.663 ± 0.001 based on the host-galaxy emission lines) and likely spectral type (type I). Using this redshift, we find MpeakU = ?21.05+0.10?0.09 for the peak, rest-frame U-band absolute magnitude, and find DES13S2cmm to be located in a faint, low-metallicity (sub-solar), low stellar-mass hostmore »galaxy (log?(M/M?) = 9.3 ± 0.3), consistent with what is seen for other SLSNe-I. We compare the bolometric light curve of DES13S2cmm to fourteen similarly well-observed SLSNe-I in the literature and find it possesses one of the slowest declining tails (beyond +30 days rest frame past peak), and is the faintest at peak. Moreover, we find the bolometric light curves of all SLSNe-I studied herein possess a dispersion of only 0.2–0.3 magnitudes between +25 and +30 days after peak (rest frame) depending on redshift range studied; this could be important for ‘standardising’ such supernovae, as is done with the more common type Ia. We fit the bolometric light curve of DES13S2cmm with two competing models for SLSNe-I – the radioactive decay of ??Ni, and a magnetar – and find that while the magnetar is formally a better fit, neither model provides a compelling match to the data. Although we are unable to conclusively differentiate between these two physical models for this particular SLSN-I, further DES observations of more SLSNe-I should break this degeneracy, especially if the light curves of SLSNe-I can be observed beyond 100 d in the rest frame of the supernova.« less

  15. Dark Energy and Dark Matter Models

    E-Print Network [OSTI]

    Burra G. Sidharth

    2015-08-27

    We revisit the problems of dark energy and dark matter and several models designed to explain them, in the light of some latest findings.

  16. Dark Energy and Dark Matter Models

    E-Print Network [OSTI]

    Burra G. Sidharth

    2015-11-30

    We revisit the problems of dark energy and dark matter and several models designed to explain them, in the light of some latest findings.

  17. DES J0454$-$4448: Discovery of the First Luminous z $\\ge$ 6 Quasar from the Dark Energy Survey

    E-Print Network [OSTI]

    Reed, S L; Banerji, M; Becker, G D; Gonzalez-Solares, E; Martini, P; Ostrovski, F; Rauch, M; Abbott, T; Abdalla, F B; Allam, S; Benoit-Levy, A; Bertin, E; Buckley-Geer, E; Burke, D; Rosell, A Carnero; da Costa, L N; ?Andrea, C; DePoy, D L; Desai, S; Diehl, H T; Doel, P; Cunha, C E; Estrada, J; Evrard, A E; Neto, A Fausti; Finley, D A; Fosalba, P; Frieman, J; Gruen, D; Honscheid, K; James, D; Kent, S; Kuehn, K; Kuropatkin, N; Lahav, O; Maia, M A G; Makler, M; Marshall, J; Merritt, K; Miquel, R; Mohr, J; Nord, B; Ogando, R; Plazas, A; Romer, K; Roodman, A; Rykoff, E; Sako, M; Sanchez, E; Santiago, B; Schubnell, M; Sevilla, I; Smith, C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Thomas, D; Tucker, D; Walker, A; Wechsler, R H

    2015-01-01

    We present the first results of a survey for high redshift, z $\\ge$ 6, quasars using izY multi-colour photometric observations from the Dark Energy Survey (DES). Here we report the discovery and spectroscopic confirmation of the $\\rm z_{AB}, Y_{AB}$ = 20.2, 20.2 (M$_{1450}$ = $-$26.5) quasar DES J0454$-$4448 with an emission line redshift of z = 6.10$\\pm$0.03 and a HI near zone size of 4.6 $\\pm$ 1.7 Mpc.The quasar was selected as an i-band drop out with i$-$z = 2.46 and z$_{AB} $ 50-100 new quasars with z $>$ 6 including 3-10 with z $>$ 7 dramatically increasing the numbers of quasars currently known that are suitable for detailed studies including determination of the neutral HI fraction of the intergalactic medium (IGM) during the epoch of Hydrogen reionization.

  18. The Dark Energy Paradigm

    E-Print Network [OSTI]

    Burra G. Sidharth

    2014-12-30

    Though the concept of a dark energy driven accelerating universe was introduced by the author in 1997, to date dark energy itself, as described below has remained a paradigm. A model for the cosmological constant is suggested.

  19. Wide-field lensing mass maps from Dark Energy Survey science verification data: Methodology and detailed analysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Vikram, V.; Sheldon, E.; Chang, C.; Jain, B.; Bacon, D.; Amara, A.; Becker, M. R.; Bernstein, G.; Bonnett, C.; Bridle, S.; et al

    2015-07-29

    Weak gravitational lensing allows one to reconstruct the spatial distribution of the projected mass density across the sky. These “mass maps” provide a powerful tool for studying cosmology as they probe both luminous and dark matter. In this paper, we present a weak lensing mass map reconstructed from shear measurements in a 139 deg2 area from the Dark Energy Survey science verification data. We compare the distribution of mass with that of the foreground distribution of galaxies and clusters. The overdensities in the reconstructed map correlate well with the distribution of optically detected clusters. We demonstrate that candidate superclusters andmore »voids along the line of sight can be identified, exploiting the tight scatter of the cluster photometric redshifts. We cross-correlate the mass map with a foreground magnitude-limited galaxy sample from the same data. Our measurement gives results consistent with mock catalogs from N-body simulations that include the primary sources of statistical uncertainties in the galaxy, lensing, and photo-z catalogs. The statistical significance of the cross-correlation is at the 6.8? level with 20 arcminute smoothing. We find that the contribution of systematics to the lensing mass maps is generally within measurement uncertainties. We analyze less than 3% of the final area that will be mapped by the DES; the tools and analysis techniques developed in this paper can be applied to forthcoming larger data sets from the survey.« less

  20. Wide-field lensing mass maps from Dark Energy Survey science verification data: Methodology and detailed analysis

    SciTech Connect (OSTI)

    Vikram, V.; Sheldon, E.; Chang, C.; Jain, B.; Bacon, D.; Amara, A.; Becker, M. R.; Bernstein, G.; Bonnett, C.; Bridle, S.; Brout, D.; Busha, M.; Frieman, J.; Gaztanaga, E.; Hartley, W.; Jarvis, M.; Kacprzak, T.; Kovacs, A.; Lahav, O.; Leistedt, B.; Lin, H.; Melchior, P.; Peiris, H.; Rozo, E.; Rykoff, E.; Sanchez, C.; Sheldon, E.; Troxel, M. A.; Wechsler, R.; Zuntz, J.; Abbott, T.; Abdalla, F. B.; Armstrong, R.; Banerji, M.; Bauer, A. H.; Benoit-Levy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Kind, M. Carrasco; Castander, F. J.; Crocce, M.; Cunha, C. E.

    2015-07-29

    Weak gravitational lensing allows one to reconstruct the spatial distribution of the projected mass density across the sky. These “mass maps” provide a powerful tool for studying cosmology as they probe both luminous and dark matter. In this paper, we present a weak lensing mass map reconstructed from shear measurements in a 139 deg2 area from the Dark Energy Survey science verification data. We compare the distribution of mass with that of the foreground distribution of galaxies and clusters. The overdensities in the reconstructed map correlate well with the distribution of optically detected clusters. We demonstrate that candidate superclusters and voids along the line of sight can be identified, exploiting the tight scatter of the cluster photometric redshifts. We cross-correlate the mass map with a foreground magnitude-limited galaxy sample from the same data. Our measurement gives results consistent with mock catalogs from N-body simulations that include the primary sources of statistical uncertainties in the galaxy, lensing, and photo-z catalogs. The statistical significance of the cross-correlation is at the 6.8? level with 20 arcminute smoothing. We find that the contribution of systematics to the lensing mass maps is generally within measurement uncertainties. We analyze less than 3% of the final area that will be mapped by the DES; the tools and analysis techniques developed in this paper can be applied to forthcoming larger data sets from the survey.

  1. Comparing Dark Energy Survey and HST-CLASH observations of the galaxy cluster RXC J2248.7-4431: implications for stellar mass versus dark matter

    E-Print Network [OSTI]

    Palmese, A; Banerji, M; Gruen, D; Jouvel, S; Melchior, P; Aleksi?, J; Annis, J; Diehl, H T; Jeltema, T; Romer, K; Rozo, E; Rykoff, E S; Seitz, S; Suchyta, E; Zhang, Y; Abbott, T M C; Abdalla, F B; Allam, S; Benoit-Lévy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Capozzi, D; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; Cunha, C E; D'Andrea, C B; da Costa, L N; Desai, S; Dietrich, J P; Doel, P; Estrada, J; Evrard, A E; Flaugher, B; Frieman, J; Gerdes, D W; Goldstein, D A; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Kuropatkin, N; Li, T S; Lima, M; Maia, M A G; Marshall, J L; Miller, C J; Miquel, R; Nord, B; Ogando, R; Plazas, A A; Roodman, A; Sanchez, E; Scarpine, V; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Swanson, M E C; Tarle, G; Thomas, D; Tucker, D; Vikram, V

    2016-01-01

    We derive the stellar mass fraction in the galaxy cluster RXC J2248.7-4431 observed with the Dark Energy Survey (DES) during the Science Verification period. We compare the stellar mass results from DES (5 filters) with those from the Hubble Space Telescope CLASH (17 filters). When the cluster spectroscopic redshift is assumed, we show that stellar masses from DES can be estimated within 25% of CLASH values. We compute the stellar mass contribution coming from red and blue galaxies, and study the relation between stellar mass and the underlying dark matter using weak lensing studies with DES and CLASH. An analysis of the radial profiles of the DES total and stellar mass yields a stellar-to-total fraction of f*=7.0+-2.2x10^-3 within a radius of r_200c~3 Mpc. Our analysis also includes a comparison of photometric redshifts and star/galaxy separation efficiency for both datasets. We conclude that space-based small field imaging can be used to calibrate the galaxy properties in DES for the much wider field of vie...

  2. Matter Field, Dark Matter and Dark Energy

    E-Print Network [OSTI]

    Masayasu Tsuge

    2009-03-24

    A model concerning particle theory and cosmology is proposed. Matter field, dark matter and dark energy are created by an energy flow from space to primordial matter fields at the phase transition in the early universe.

  3. The Dark Energy Camera

    E-Print Network [OSTI]

    Flaugher, B; Honscheid, K; Abbott, T M C; Alvarez, O; Angstadt, R; Annis, J T; Antonik, M; Ballester, O; Beaufore, L; Bernstein, G M; Bernstein, R A; Bigelow, B; Bonati, M; Boprie, D; Brooks, D; Buckley-Geer, E J; Campa, J; Cardiel-Sas, L; Castander, F J; Castilla, J; Cease, H; Cela-Ruiz, J M; Chappa, S; Chi, E; Cooper, C; da Costa, L N; Dede, E; Derylo, G; DePoy, D L; de Vicente, J; Doel, P; Drlica-Wagner, A; Eiting, J; Elliott, A E; Emes, J; Estrada, J; Neto, A Fausti; Finley, D A; Flores, R; Frieman, J; Gerdes, D; Gladders, M D; Gregory, B; Gutierrez, G R; Hao, J; Holland, S E; Holm, S; Huffman, D; Jackson, C; James, D J; Jonas, M; Karcher, A; Karliner, I; Kent, S; Kessler, R; Kozlovsky, M; Kron, R G; Kubik, D; Kuehn, K; Kuhlmann, S; Kuk, K; Lahav, O; Lathrop, A; Lee, J; Levi, M E; Lewis, P; Li, T S; Mandrichenko, I; Marshall, J L; Martinez, G; Merritt, K W; Miquel, R; Munoz, F; Neilsen, E H; Nichol, R C; Nord, B; Ogando, R; Olsen, J; Palio, N; Patton, K; Peoples, J; Plazas, A A; Rauch, J; Reil, K; Rheault, J -P; Roe, N A; Rogers, H; Roodman, A; Sanchez, E; Scarpine, V; Schindler, R H; Schmidt, R; Schmitt, R; Schubnell, M; Schultz, K; Schurter, P; Scott, L; Serrano, S; Shaw, T M; Smith, R C; Soares-Santos, M; Stefanik, A; Stuermer, W; Suchyta, E; Sypniewski, A; Tarle, G; Thaler, J; Tighe, R; Tran, C; Tucker, D; Walker, A R; Wang, G; Watson, M; Weaverdyck, C; Wester, W; Woods, R; Yanny, B

    2015-01-01

    The Dark Energy Camera is a new imager with a 2.2-degree diameter field of view mounted at the prime focus of the Victor M. Blanco 4-meter telescope on Cerro Tololo near La Serena, Chile. The camera was designed and constructed by the Dark Energy Survey Collaboration, and meets or exceeds the stringent requirements designed for the wide-field and supernova surveys for which the collaboration uses it. The camera consists of a five element optical corrector, seven filters, a shutter with a 60 cm aperture, and a CCD focal plane of 250 micron thick fully-depleted CCDs cooled inside a vacuum Dewar. The 570 Mpixel focal plane comprises 62 2kx4k CCDs for imaging and 12 2kx2k CCDs for guiding and focus. The CCDs have 15 microns x15 microns pixels with a plate scale of 0.263 arc sec per pixel. A hexapod system provides state-of-the-art focus and alignment capability. The camera is read out in 20 seconds with 6-9 electrons readout noise. This paper provides a technical description of the camera's engineering, construct...

  4. Natural Dark Energy

    E-Print Network [OSTI]

    Douglas Scott; Ali Frolop

    2007-03-30

    It is now well accepted that both Dark Matter and Dark Energy are required in any successful cosmological model. Although there is ample evidence that both Dark components are necessary, the conventional theories make no prediction for the contributions from each of them. Moreover, there is usually no intrinsic relationship between the two components, and no understanding of the nature of the mysteries of the Dark Sector. Here we suggest that if the Dark Side is so seductive then we should not be restricted to just 2 components. We further suggest that the most natural model has 5 distinct forms of Dark Energy in addition to the usual Dark Matter, each contributing precisely equally to the cosmic energy density budget.

  5. Dynamical Mutation of Dark Energy

    E-Print Network [OSTI]

    L. R. Abramo; R. C. Batista; L. Liberato; R. Rosenfeld

    2008-01-03

    We discuss the intriguing possibility that dark energy may change its equation of state in situations where large dark energy fluctuations are present. We show indications of this dynamical mutation in some generic models of dark energy.

  6. Dynamical mutation of dark energy

    SciTech Connect (OSTI)

    Abramo, L. R.; Batista, R. C. [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05315-970, Sao Paulo (Brazil); Liberato, L.; Rosenfeld, R. [Instituto de Fisica Teorica, Universidade Estadual Paulista, R. Pamplona 145, 01405-900, Sao Paulo (Brazil)

    2008-03-15

    We discuss the intriguing possibility that dark energy may change its equation of state in situations where large dark energy fluctuations are present. We show indications of this dynamical mutation in some generic models of dark energy.

  7. Dark Energy in the Dark Ages

    E-Print Network [OSTI]

    Linder, Eric V.

    2009-01-01

    fraction of dark energy density today and at the CMB lastenergy density at high redshifts causes strong deviations in the total linear growth achieved by today,

  8. Superconducting dark energy

    E-Print Network [OSTI]

    Shi-Dong Liang; Tiberiu Harko

    2015-04-10

    Based on the analogy with superconductor physics we consider a scalar-vector-tensor gravitational model, in which the dark energy action is described by a gauge invariant electromagnetic type functional. By assuming that the ground state of the dark energy is in a form of a condensate with the U(1) symmetry spontaneously broken, the gauge invariant electromagnetic dark energy can be described in terms of the combination of a vector and of a scalar field (corresponding to the Goldstone boson), respectively. The gravitational field equations are obtained by also assuming the possibility of a non-minimal coupling between the cosmological mass current and the superconducting dark energy. The cosmological implications of the dark energy model are investigated for a Friedmann-Robertson-Walker homogeneous and isotropic geometry for two particular choices of the electromagnetic type potential, corresponding to a pure electric type field, and to a pure magnetic field, respectively. The time evolution of the scale factor, matter energy density and deceleration parameter are obtained for both cases, and it is shown that in the presence of the superconducting dark energy the Universe ends its evolution in an exponentially accelerating vacuum de Sitter state. By using the formalism of the irreversible thermodynamic processes for open systems we interpret the generalized conservation equations in the superconducting dark energy model as describing matter creation. The particle production rates, the creation pressure and the entropy evolution are explicitly obtained.

  9. The Sloan Digital Sky Survey Quasar Lens Search. VI. Constraints on Dark Energy and the Evolution of Massive Galaxies

    SciTech Connect (OSTI)

    Oguri, Masamune; et al.

    2012-05-01

    We present a statistical analysis of the final lens sample from the Sloan Digital Sky Survey Quasar Lens Search (SQLS). The number distribution of a complete subsample of 19 lensed quasars selected from 50,836 source quasars is compared with theoretical expectations, with particular attention to the selection function. Assuming that the velocity function of galaxies does not evolve with redshift, the SQLS sample constrains the cosmological constant to \\Omega_\\Lambda=0.79^{+0.06}_{-0.07}(stat.)^{+0.06}_{-0.06}(syst.) for a flat universe. The dark energy equation of state is found to be consistent with w=-1 when the SQLS is combined with constraints from baryon acoustic oscillation (BAO) measurements or results from the Wilkinson Microwave Anisotropy Probe (WMAP). We also obtain simultaneous constraints on cosmological parameters and redshift evolution of the galaxy velocity function, finding no evidence for redshift evolution at z<1 in any combinations of constraints. For instance, number density evolution quantified as \

  10. Dark Energy, or Worse

    ScienceCinema (OSTI)

    Professor Sean Carroll

    2010-01-08

    General relativity is inconsistent with cosmological observations unless we invoke components of dark matter and dark energy that dominate the universe. While it seems likely that these exotic substances really do exist, the alternative is worth considering: that Einstein's general relativity breaks down on cosmological scales. I will discuss models of modified gravity, tests in the solar system and elsewhere, and consequences for cosmology.

  11. Dark Energy, or Worse

    SciTech Connect (OSTI)

    Carroll, Sean (CalTech) [CalTech

    2006-11-13

    General relativity is inconsistent with cosmological observations unless we invoke components of dark matter and dark energy that dominate the universe. While it seems likely that these exotic substances really do exist, the alternative is worth considering: that Einstein's general relativity breaks down on cosmological scales. I will discuss models of modified gravity, tests in the solar system and elsewhere, and consequences for cosmology.

  12. Dark Energy in the Dark Ages

    E-Print Network [OSTI]

    Eric V. Linder

    2006-04-11

    Non-negligible dark energy density at high redshifts would indicate dark energy physics distinct from a cosmological constant or ``reasonable'' canonical scalar fields. Such dark energy can be constrained tightly through investigation of the growth of structure, with limits of \\la2% of total energy density at z\\gg1 for many models. Intermediate dark energy can have effects distinct from its energy density; the dark ages acceleration can be constrained to last less than 5% of a Hubble e-fold time, exacerbating the coincidence problem. Both the total linear growth, or equivalently \\sigma_8, and the shape and evolution of the nonlinear mass power spectrum for zenergy behavior over the entire range z=0-1100.

  13. The Dark Energy Universe

    E-Print Network [OSTI]

    Burra G. Sidharth

    2015-01-12

    Some seventy five years ago, the concept of dark matter was introduced by Zwicky to explain the anomaly of galactic rotation curves, though there is no clue to its identity or existence to date. In 1997, the author had introduced a model of the universe which went diametrically opposite to the existing paradigm which was a dark matter assisted decelarating universe. The new model introduces a dark energy driven accelarating universe though with a small cosmological constant. The very next year this new picture was confirmed by the Supernova observations of Perlmutter, Riess and Schmidt. These astronomers got the 2011 Nobel Prize for this dramatic observation. All this is discussed briefly, including the fact that dark energy may obviate the need for dark matter.

  14. Coupling dark energy to dark matter perturbations

    E-Print Network [OSTI]

    Valerio Marra

    2015-06-21

    This Letter proposes that dark energy in the form of a scalar field could effectively couple to dark matter perturbations. The idea is that dark matter particles could annihilate/interact inside dense clumps and transfer energy to the scalar field, which would then enter an accelerated regime. This hypothesis is interesting as it provides a natural trigger for the onset of the acceleration of the universe, since dark energy starts driving the expansion of the universe when matter perturbations become sufficiently dense. Here we study a possible realization of this general idea by coupling dark energy to dark matter via the linear growth function of matter perturbations. The numerical results show that it is indeed possible to obtain a viable cosmology with the expected series of radiation, matter and dark-energy dominated eras. Moreover, the current density of dark energy is given by the value of the coupling parameters rather than by very special initial conditions for the scalar field. In other words, this model does not suffer from the so-called "coincidence problem" and its related fine tuning of initial conditions.

  15. Coupling dark energy to dark matter perturbations

    E-Print Network [OSTI]

    Marra, Valerio

    2015-01-01

    This Letter proposes that dark energy in the form of a scalar field could effectively couple to dark matter perturbations. The idea is that dark matter particles could annihilate/interact inside dense clumps and transfer energy to the scalar field, which would then enter an accelerated regime. This hypothesis is interesting as it provides a natural trigger for the onset of the acceleration of the universe, since dark energy starts driving the expansion of the universe when matter perturbations become sufficiently dense. Here we study a possible realization of this general idea by coupling dark energy to dark matter via the linear growth function of matter perturbations. The numerical results show that it is indeed possible to obtain a viable cosmology with the expected series of radiation, matter and dark-energy dominated eras. Moreover, the current density of dark energy is given by the value of the coupling parameters rather than by very special initial conditions for the scalar field. In other words, this ...

  16. OzDES multifibre spectroscopy for the Dark Energy Survey: First-year operation and results

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yuan, Fang; Plazas, A. A.; Lidman, C.; Davis, T. M.; Childress, M.; Abdalla, F. B.

    2015-07-29

    OzDES is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim is to measure redshifts of approximately 2,500 Type Ia supernovae host galaxies over the redshift range 0.1 more »help calibrate photometric redshifts. Here we present an overview of the OzDES program and our first-year results. Between Dec 2012 and Dec 2013, we observed over 10,000 objects and measured more than 6,000 redshifts. Our strategy of retargeting faint objects across many observing runs has allowed us to measure redshifts for galaxies as faint as mr = 25 mag. We outline our target selection and observing strategy, quantify the redshift success rate for different types of targets, and discuss the implications for our main science goals. Finally, we highlight a few interesting objects as examples of the fortuitous yet not totally unexpected discoveries that can come from such a large spectroscopic survey.« less

  17. Dark Energy, Gravitation and Electromagnetism

    E-Print Network [OSTI]

    B. G. Sidharth

    2004-01-08

    In the context of the fact that the existence of dark energy causing the accelerated expansion of the universe has been confirmed by the WMAP and the Sloan Digital Sky Survey, we re-examine gravitation itself, starting with the formulation of Sakharov and show that it is possible to obtain gravitation in terms of the electromagnetic charge of elementary particles, once the ZPF and its effects at the Compton scale are taken into account.

  18. Dark Energy Studies: Challenges to Computational Cosmology

    E-Print Network [OSTI]

    James Annis; Francisco J. Castander; August E. Evrard; Joshua A. Frieman; Enrique Gaztanaga; Bhuvnesh Jain; Andrey V. Kravtsov; Ofer Lahav; Huan Lin; Joseph Mohr; Paul M. Ricker; Albert Stebbins; Risa H. Wechsler; David H. Weinberg; Jochen Weller

    2005-10-06

    The ability to test the nature of dark mass-energy components in the universe through large-scale structure studies hinges on accurate predictions of sky survey expectations within a given world model. Numerical simulations predict key survey signatures with varying degrees of confidence, limited mainly by the complex astrophysics of galaxy formation. As surveys grow in size and scale, systematic uncertainties in theoretical modeling can become dominant. Dark energy studies will challenge the computational cosmology community to critically assess current techniques, develop new approaches to maximize accuracy, and establish new tools and practices to efficiently employ globally networked computing resources.

  19. Dark Energy Studies: Challenges to Computational Cosmology

    E-Print Network [OSTI]

    Annis, J; Evrard, A E; Frieman, J A; Gaztañaga, E; Jain, B; Kravtsov, A V; Lahav, O; Lin, H; Mohr, J; Ricker, P M; Stebbins, A; Wechsler, R H; Weinberg, D H; Weller, J; Annis, James; Castander, Francisco J.; Evrard, August E.; Frieman, Joshua A.; Gaztanaga, Enrique; Jain, Bhuvnesh; Kravtsov, Andrey V.; Lahav, Ofer; Lin, Huan; Mohr, Joseph; Ricker, Paul M.; Stebbins, Albert; Wechsler, Risa H.; Weinberg, David H.; Weller, Jochen

    2005-01-01

    The ability to test the nature of dark mass-energy components in the universe through large-scale structure studies hinges on accurate predictions of sky survey expectations within a given world model. Numerical simulations predict key survey signatures with varying degrees of confidence, limited mainly by the complex astrophysics of galaxy formation. As surveys grow in size and scale, systematic uncertainties in theoretical modeling can become dominant. Dark energy studies will challenge the computational cosmology community to critically assess current techniques, develop new approaches to maximize accuracy, and establish new tools and practices to efficiently employ globally networked computing resources.

  20. Big Mysteries: Dark Energy

    ScienceCinema (OSTI)

    Lincoln, Don

    2014-08-07

    Scientists were shocked in 1998 when the expansion of the universe wasn't slowing down as expected by our best understanding of gravity at the time; the expansion was speeding up! That observation is just mind blowing, and yet it is true. In order to explain the data, physicists had to resurrect an abandoned idea of Einstein's now called dark energy. In this video, Fermilab's Dr. Don Lincoln tells us a little about the observations that led to the hypothesis of dark energy and what is the status of current research on the subject.

  1. Big Mysteries: Dark Energy

    SciTech Connect (OSTI)

    Lincoln, Don

    2014-04-15

    Scientists were shocked in 1998 when the expansion of the universe wasn't slowing down as expected by our best understanding of gravity at the time; the expansion was speeding up! That observation is just mind blowing, and yet it is true. In order to explain the data, physicists had to resurrect an abandoned idea of Einstein's now called dark energy. In this video, Fermilab's Dr. Don Lincoln tells us a little about the observations that led to the hypothesis of dark energy and what is the status of current research on the subject.

  2. Interacting Dark Matter and Dark Energy

    E-Print Network [OSTI]

    Glennys R. Farrar; P. J. E. Peebles

    2003-09-23

    We discuss models for the cosmological dark sector in which the energy density of a scalar field approximates Einstein's cosmological constant and the scalar field value determines the dark matter particle mass by a Yukawa coupling. A model with one dark matter family can be adjusted so the observational constraints on the cosmological parameters are close to but different from what is predicted by the Lambda CDM model. This may be a useful aid to judging how tightly the cosmological parameters are constrained by the new generation of cosmological tests that depend on the theory of structure formation. In a model with two families of dark matter particles the scalar field may be locked to near zero mass for one family. This can suppress the long-range scalar force in the dark sector and eliminate evolution of the effective cosmological constant and the mass of the nonrelativistic dark matter particles, making the model close to Lambda CDM, until the particle number density becomes low enough to allow the scalar field to evolve. This is a useful example of the possibility for complexity in the dark sector.

  3. Dark Energy and Electrons

    E-Print Network [OSTI]

    Burra G. Sidharth

    2008-08-05

    In the light of recent developments in Dark Energy, we consider the electron in a such a background field and show that at the Compton wavelength the electron is stable, in that the Cassini inward pressure exactly counterbalances the outward Coulomb repulsive pressure thus answering a problem of the earlier electron theory.

  4. Unified Description of Dark Energy and Dark Matter

    E-Print Network [OSTI]

    Walter Petry

    2008-11-09

    Dark energy in the universe is assumed to be vacuum energy. The energy-momentum of vacuum is described by a scale-dependent cosmological constant. The equations of motion imply for the density of matter (dust) the sum of the usual matter density (luminous matter) and an additional matter density (dark matter) similar to the dark energy. The scale-dependent cosmological constant is given up to an exponent which is approximated by the experimentally decided density parameters of dark matter and dark energy. This yields that dark matter is one third of dark energy for all times implying an explanation of the coincidence of dark matter and dark energy. In the final state, the universe becomes dark, consisting of dark matter and dark energy.

  5. Alternatives to Dark Matter and Dark Energy

    E-Print Network [OSTI]

    Philip D. Mannheim

    2005-08-01

    We review the underpinnings of the standard Newton-Einstein theory of gravity, and identify where it could possibly go wrong. In particular, we discuss the logical independence from each other of the general covariance principle, the equivalence principle and the Einstein equations, and discuss how to constrain the matter energy-momentum tensor which serves as the source of gravity. We identify the a priori assumption of the validity of standard gravity on all distance scales as the root cause of the dark matter and dark energy problems, and discuss how the freedom currently present in gravitational theory can enable us to construct candidate alternatives to the standard theory in which the dark matter and dark energy problems could then be resolved. We identify three generic aspects of these alternate approaches: that it is a universal acceleration scale which determines when a luminous Newtonian expectation is to fail to fit data, that there is a global cosmological effect on local galactic motions which can replace galactic dark matter, and that to solve the cosmological constant problem it is not necessary to quench the cosmological constant itself, but only the amount by which it gravitates.

  6. Probing Dark Energy with Black Hole Binaries

    E-Print Network [OSTI]

    Laura Mersini-Houghton; Adam Kelleher

    2008-08-25

    The equation of state (EoS) of dark energy $w$ remains elusive despite enormous experimental efforts to pin down its value and its time variation. Yet it is the single most important handle we have in our understanding of one of the most mysterious puzzle in nature, dark energy. This letter proposes a new method for measuring the EoS of dark energy by using the gravitational waves (GW) of black hole binaries. The method described here offers an alternative to the standard way of large scale surveys. It is well known that the mass of a black hole changes due to the accretion of dark energy but at an extremely slow rate. However, a binary of supermassive black holes (SBH) radiates gravitational waves with a power proportional to the masses of these accreting stars and thereby carries information on dark energy. These waves can propagate through the vastness of structure in the universe unimpeded. The orbital changes of the binary, induced by the energy loss from gravitational radiation, receive a large contribution from dark energy accretion. This contribution is directly proportional to $(1+w)$ and is dominant for SBH binaries with separation $R \\ge 1000$ parsec, thereby accelerating the merging process for $w > -1$ or ripping the stars apart for phantom dark energy with $w < -1$. Such orbital changes, therefore $w$, can be detected with LIGO and LISA near merging time, or with X-ray and radio measurements of Chandra and VLBA experiments.

  7. The Dark Side: from Dark Energy & Dark Matter to Washington and Science Policy

    E-Print Network [OSTI]

    Collar, Juan I.

    The Dark Side: from Dark Energy & Dark Matter to Washington and Science Policy Presenter: Michael: The Map Room (www.maproom.com )1949 N. Hoyne #12;The Dark Side: from Dark Energy and Dark Matter to Washington and Science Policy Presenter: Michael S. Turner Time & Date: 7-9 PM Monday June 16, 2008 Location

  8. Alternatives to Dark Matter and Dark Energy

    E-Print Network [OSTI]

    Mannheim, P D

    2006-01-01

    We review the underpinnings of the standard Newton-Einstein theory of gravity, and identify where it could possibly go wrong. In particular, we discuss the logical independence from each other of the general covariance principle, the equivalence principle and the Einstein equations, and discuss how to constrain the matter energy-momentum tensor which serves as the source of gravity. We identify the a priori assumption of the validity of standard gravity on all distance scales as the root cause of the dark matter and dark energy problems, and discuss how the freedom currently present in gravitational theory can enable us to construct candidate alternatives to the standard theory in which the dark matter and dark energy problems could then be resolved. We identify three generic aspects of these alternate approaches: that it is a universal acceleration scale which determines when a luminous Newtonian expectation is to fail to fit data, that there is a global cosmological effect on local galactic motions which ca...

  9. Dark energy and curvature from a future baryonic acoustic oscillation survey using the Lyman-alpha forest

    E-Print Network [OSTI]

    Patrick McDonald; Daniel Eisenstein

    2006-07-07

    We explore the requirements for a Lyman-alpha forest (LyaF) survey designed to measure the angular diameter distance and Hubble parameter at 2~Energy Task Force Figure of Merit, relative to the case with only a similar precision measurement at z~1, if the Universe is not assumed to be flat. This improvement is greater than the one obtained by doubling the size of the z~1 survey, with Planck and a weak SDSS-like z=0.3 BAO measurement assumed in each case. Galaxy BAO surveys at z~1 may be able to make an effective LyaF measurement simultaneously at minimal added cost, because the required number density of quasars is relatively small. We discuss the constraining power as a function of area, magnitude limit (density of quasars), resolution, and signal-to-noise of the spectra. For example, a survey covering 2000 sq. deg. and achieving S/N=1.8 per Ang. at g=23 (~40 quasars per sq. deg.) with an R~>250 spectrograph is sufficient to measure both the radial and transverse oscillation scales to 1.4% from the LyaF (or better, if fainter magnitudes and possibly Lyman-break galaxies can be used). At fixed integration time and in the sky-noise-dominated limit, a wider, noisier survey is generally more efficient; the only fundamental upper limit on noise being the need to identify a quasar and find a redshift. Because the LyaF is much closer to linear and generally better understood than galaxies, systematic errors are even less likely to be a problem.

  10. OzDES multi-fibre spectroscopy for the Dark Energy Survey: first-year operation and results

    E-Print Network [OSTI]

    Yuan, Fang; Davis, T M; Childress, M; Abdalla, F B; Banerji, M; Buckley-Geer, E; Rosell, A Carnero; Carollo, D; Castander, F J; D'Andrea, C B; Diehl, H T; Cunha, C E; Foley, R J; Frieman, J; Glazebrook, K; Gschwend, J; Hinton, S; Jouvel, S; Kessler, R; Kim, A G; King, A L; Kuehn, K; Kuhlmann, S; Lewis, G F; Lin, H; Martini, P; McMahon, R G; Mould, J; Nichol, R C; Norris, R P; O'Neill, C R; Ostrovski, F; Papadopoulos, A; Parkinson, D; Reed, S; Romer, A K; Rooney, P J; Rozo, E; Rykoff, E S; Sako, M; Scalzo, R; Schmidt, B P; Scolnic, D; Seymour, N; Sharp, R; Sobreira, F; Sullivan, M; Thomas, R C; Tucker, D; Uddin, S A; Wechsler, R H; Wester, W; Wilcox, H; Zhang, B; Abbott, T; Allam, S; Bauer, A H; Benoit-Levy, A; Bertin, E; Brooks, D; Burke, D L; Kind, M Carrasco; Covarrubias, R; Crocce, M; da Costa, L N; DePoy, D L; Desai, S; Doel, P; Eifler, T F; Evrard, A E; Neto, A Fausti; Flaugher, B; Fosalba, P; Gaztanaga, E; Gerdes, D; Gruen, D; Gruendl, R A; Honscheid, K; James, D; Kuropatkin, N; Lahav, O; Li, T S; Maia, M A G; Makler, M; Marshall, J; Miller, C J; Miquel, R; Ogando, R; Plazas, A A; Roodman, A; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Walker, A R

    2015-01-01

    OzDES is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim is to measure redshifts of approximately 2,500 Type Ia supernovae host galaxies over the redshift range 0.1 Energy Survey for which we are also targeting cluster galaxies, radio galaxies, strong lenses, and unidentified transients, as well as measuring luminous red galaxies and emission line galaxies to help calibrate photometric redshifts. Here we present an overview of the OzDES program and our first-year results. Between Dec 2012 and Dec 2013, we observed over 10,000 objects and measured more than 6,000 redshifts. Our strategy of retargeting faint objects across many observing runs has allowed us to measure redshifts for galaxies as faint as m_r=25 mag. We outline ...

  11. The Sloan Digital Sky Survey Quasar Lens Search. III Constraints on Dark Energy From The Third Data Release Quasar Lens Catalog

    SciTech Connect (OSTI)

    Oguri, M; Inada, N; Strauss, M A; Kochanek, C S; Richards, G T; Schneider, D P; Becker, R H; Fukugita, M; Gregg, M D; Hall, P B; Hennawi, J F; Johnston, D E; Kayo, I; Keeton, C R; Pindor, B; Shin, M; Turner, E; White, R L; York, D G; Anderson, S F; Bahcall, N A; Brunner, R J; Burles, S; Castander, F J; Chiu, K; Clocchiatti, A; Einsenstein, D; Frieman, J; Kawano, Y; Lupton, R; Morokuma, T; Rix, H; Scranton, R; Sheldon, E S

    2007-09-12

    We present cosmological results from the statistics of lensed quasars in the Sloan Digital Sky Survey (SDSS) Quasar Lens Search. By taking proper account of the selection function, we compute the expected number of quasars lensed by early-type galaxies and their image separation distribution assuming a flat universe, which is then compared with 7 lenses found in the SDSS Data Release 3 to derive constraints on dark energy under strictly controlled criteria. For a cosmological constant model (w = -1) we obtain {Omega}{sub {Lambda}} = 0.74{sub -0.15}{sup +0.11}(stat.){sub -0.06}{sup +0.13}(syst.). Allowing w to be a free parameter we find {Omega}{sub M} = 0.26{sub -0.06}{sup +0.07}(stat.){sub -0.05}{sup +0.03}(syst.) and w = -1.1 {+-} 0.6(stat.){sub -0.5}{sup +0.3}(syst.) when combined with the constraint from the measurement of baryon acoustic oscillations in the SDSS luminous red galaxy sample. Our results are in good agreement with earlier lensing constraints obtained using radio lenses, and provide additional confirmation of the presence of dark energy consistent with a cosmological constant, derived independently of type Ia supernovae.

  12. Dark Matter and Dark Energy: Summary and Future Directions

    E-Print Network [OSTI]

    John Ellis

    2003-04-10

    This paper reviews the progress reported at this Royal Society Discussion Meeting and advertizes some possible future directions in our drive to understand dark matter and dark energy. Additionally, a first attempt is made to place in context the exciting new results from the WMAP satellite, which were published shortly after this Meeting. In the first part of this review, pieces of observational evidence shown here that bear on the amounts of dark matter and dark energy are reviewed. Subsequently, particle candidates for dark matter are mentioned, and detection strategies are discussed. Finally, ideas are presented for calculating the amounts of dark matter and dark energy, and possibly relating them to laboratory data.

  13. Digging deeper into the Southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data

    E-Print Network [OSTI]

    Luque, E; Santiago, B; Pieres, A; Balbinot, E; Bechtol, K; Drlica-Wagner, A; Neto, A Fausti; da Costa, L N; Maia, M A G; Yanny, B; Abbott, T; Allam, S; Benoit-Lévy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Cunha, C E; Desai, S; Diehl, H T; Dietrich, J P; Eifler, T F; Finley, D A; Flaugher, B; Fosalba, P; Frieman, J; Gerdes, D W; Gruen, D; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; March, M; Marshall, J L; Martini, P; Miquel, R; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Tucker, D; Walker, A R; Zhang, Y

    2015-01-01

    The Dark Energy Survey (DES) is a 5000 sq. degree survey in the southern hemisphere, which is rapidly reducing the existing north-south asymmetry in the census of MW satellites and other stellar substructure. We use the first-year DES data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old a...

  14. Cross-correlation of WMAP 3rd year and the SDSS DR4 galaxy survey: new evidence for Dark Energy

    E-Print Network [OSTI]

    Cabre, A; Manera, M; Fosalba, P; Castander, F

    2006-01-01

    We cross-correlate the third-year WMAP data with galaxy samples extracted from the SDSS DR4 covering 13% of the sky, increasing by a factor of 3.7 the volume sampled in previous analyses. The new measurements confirm a positive cross-correlation with higher significance (total signal-to-noise of about 4.7). The correlation as a function of angular scale is well fitted by the integrated Sachs-Wolfe (ISW) effect for LCDM flat FRW models with a cosmological constant (w=-1). The combined analysis of different samples gives Omega_L=0.75-0.80 (68% Confidence Level, CL) or 0.70-0.82 (95% CL). We find that the best fit Omega_L decreases from 0.82 to 0.75 (95% CL) when we increase the median redshift of the galaxy sample from z~0.3 to z~0.5. The quick drop of the measured signal with z is too fast for the LCDM cosmology. The data can be better reconciled with a model with an effective dark energy equation of state w<-1.5. Such phantom cosmology reduces by up to ~20% the amplitude of the lower multipoles of the CMB ...

  15. Dark Energy Present and Future

    E-Print Network [OSTI]

    Paul H. Frampton

    2003-07-03

    By studying the present cosmological data, particularly on CMB, SNeIA and LSS, we find that the future fate of the universe, for simple linear models of the dark energy equation-of-state, can vary between the extremes of (I) a divergence of the scale factor in as little as 7 Gyr; (II) an infinite lifetime of the universe with dark energy dominant for all future time; (III) a disappearing dark energy where the universe asymptotes as $t \\to \\infty$ to $a(t) \\sim t^{2/3}$ {\\it i.e.} matter domination. Precision cosmological data hint that a dark energy with equation of state $w = P/\\rho 0$ to $\\Lambda = 0$ in a first-order phase transition. The critical radius is argued to be at least of galactic size and the corresponding nucleation rate glacial, thus underwriting the dark energy's stability and rendering remote any microscopic effect.

  16. Exploring dark matter microphysics with galaxy surveys

    E-Print Network [OSTI]

    Escudero, Miguel; Vincent, Aaron C; Wilkinson, Ryan J; Boehm, Celine

    2015-01-01

    We use present cosmological observations and forecasts of future experiments to illustrate the power of large-scale structure (LSS) surveys in probing dark matter (DM) microphysics and unveiling potential deviations from the standard $\\Lambda$CDM scenario. To quantify this statement, we focus on an extension of $\\Lambda$CDM with DM-neutrino scattering, which leaves a distinctive imprint on the angular and matter power spectra. After finding that future CMB experiments (such as COrE+) will not significantly improve the constraints set by the Planck satellite, we show that the next generation of galaxy clustering surveys (such as DESI) could play a leading role in constraining alternative cosmologies and even have the potential to make a discovery. Typically, we find that DESI would be an order of magnitude more sensitive to DM interactions than Planck (if s-wave) and two orders of magnitude (if p-wave), thus probing effects that until now have only been accessible via N-body simulations.

  17. Discovering the Nature of Dark Energy: Towards Better Distances...

    Office of Scientific and Technical Information (OSTI)

    with SNe Ia from the Sloan Digital Sky Survey (SDSS). These Hubble diagrams provide useful new constraints on the nature of the dark energy that is accelerating the expansion...

  18. Bose Einstein Condensation as Dark Energy and Dark Matter

    E-Print Network [OSTI]

    Masako Nishiyama; Masa-aki Morita; Masahiro Morikawa

    2004-03-24

    We study a cosmological model in which the boson dark matter gradually condensates into dark energy. Negative pressure associated with the condensate yields the accelerated expansion of the Universe and the rapid collapse of the smallest scale fluctuations into many black holes, which become the seeds of the first galaxies. The cycle of gradual sedimentation and rapid collapse of condensate repeats many times and self-regularizes the ratio of dark energy and dark matter to be order one.

  19. Neutrino mixing and dark energy

    SciTech Connect (OSTI)

    Blasone, M.; Capolupo, A.; Vitiello, G. [Dipartimento di Fisica 'E.R. Caianiello', I-84100 Salerno (Italy); INFN, Universita di Salerno, I-84100 Salerno (Italy); Capozziello, S. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Compl. Univ. Monte S. Angelo, Ed.N, Via Cinthia, I-80126 Naples (Italy); INFN Sez. di Napoli, Compl. Univ. Monte S. Angelo, Ed.N, Via Cinthia, I-80126 Naples (Italy)

    2006-06-19

    We report on the recent result that the non-perturbative vacuum structure associated with neutrino mixing leads to a non-zero contribution to the value of the dark energy.

  20. Emergent gravity and Dark Energy

    E-Print Network [OSTI]

    T. Padmanabhan

    2008-02-13

    This is an invited contribution to be included in a multi-authored book on "Dark Energy", to be edited by Pilar Ruiz-Lapuente and published by Cambridge University Press.

  1. Interacting Induced Dark Energy Model

    E-Print Network [OSTI]

    Bahrehbakhsh, Amir F

    2016-01-01

    Similar to the idea of the brane world scenarios, but based on the approach of the induced matter theory, for a non--vacuum five--dimensional version of general relativity, we propose a model in which the conventional matter sources considered as all kind of the matter (the baryonic and dark) and the induced terms emerging from the extra dimension supposed to be as dark energy. Then we investigate the FLRW type cosmological equations and illustrate that the model is capable to explain respectively the deceleration and then acceleration eras of the universe expansion with an interacting term between the matter and dark energy.

  2. Dynamics of dark energy with a coupling to dark matter

    SciTech Connect (OSTI)

    Boehmer, Christian G.; Caldera-Cabral, Gabriela; Maartens, Roy; Lazkoz, Ruth

    2008-07-15

    Dark energy and dark matter are the dominant sources in the evolution of the late universe. They are currently only indirectly detected via their gravitational effects, and there could be a coupling between them without violating observational constraints. We investigate the background dynamics when dark energy is modeled as exponential quintessence and is coupled to dark matter via simple models of energy exchange. We introduce a new form of dark sector coupling, which leads to a more complicated dynamical phase space and has a better physical motivation than previous mathematically similar couplings.

  3. Dark energy from gravitoelectromagnetic inflation?

    E-Print Network [OSTI]

    Federico Agustin Membiela; Mauricio Bellini

    2008-07-29

    Gravitoectromagnetic Inflation (GI) was introduced to describe in an unified manner, electromagnetic, gravitatory and inflaton fields from a 5D vacuum state. On the other hand, the primordial origin and evolution of dark energy is today unknown. In this letter we show using GI that the zero modes of some redefined vector fields $B_i=A_i/a$ produced during inflation, could be the source of dark energy in the universe.

  4. Galaxies in X-ray Selected Clusters and Groups in Dark Energy Survey Data: Stellar Mass Growth of Bright Central Galaxies Since z~1.2

    E-Print Network [OSTI]

    Zhang, Y; Mckay, T; Rooney, P; Evrard, A E; Romer, A K; Perfecto, R; Song, J; Desai, S; Mohr, J; Wilcox, H; Bermeo, A; Jeltema, T; Hollowood, D; Bacon, D; Capozzi, D; Collins, C; Das, R; Gerdes, D; Hennig, C; Hilton, M; Hoyle, B; Kay, S; Liddle, A; Mann, R G; Mehrtens, N; Nichol, R C; Papovich, C; Sahlén, M; Soares-Santos, M; Stott, J; Viana, P T; Abbott, T; Abdalla, F B; Banerji, M; Bauer, A H; Benoit-Lévy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Rosell, A Carnero; Castander, F J; Diehl, H T; Doel, P; Cunha, C E; Eifler, T F; Neto, A Fausti; Fernandez, E; Flaugher, B; Fosalba, P; Frieman, J; Gaztanaga, E; Gruen, D; Gruendl, R A; Honscheid, K; James, D; Kuehn, K; Kuropatkin, N; Lahav, O; Maia, M A G; Makler, M; Marshall, J L; Martini, Paul; Miquel, R; Ogando, R; Plazas, A A; Roodman, A; Rykoff, E S; Sako, M; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla, I; Smith, R C; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Tucker, D; Vikram, V; Da Costa, L N

    2015-01-01

    Using the science verification data of the Dark Energy Survey (DES) for a new sample of 106 X-Ray selected clusters and groups, we study the stellar mass growth of Bright Central Galaxies (BCGs) since redshift 1.2. Compared with the expectation in a semi-analytical model applied to the Millennium Simulation, the observed BCGs become under-massive/under-luminous with decreasing redshift. We incorporate the uncertainties associated with cluster mass, redshift, and BCG stellar mass measurements into analysis of a redshift-dependent BCG-cluster mass relation, $m_{*}\\propto(\\frac{M_{200}}{1.5\\times 10^{14}M_{\\odot}})^{0.24\\pm 0.08}(1+z)^{-0.19\\pm0.34}$, and compare the observed relation to the simulation prediction. We estimate the average growth rate since z = 1.0 for BCGs hosted by clusters of $M_{200, z}=10^{13.8}M_{\\odot}$, at $z=1.0$: $m_{*, BCG}$ appears to have grown by $0.13\\pm0.11$ dex, in tension at $\\sim 2.5 \\sigma$ significance level with the 0.4 dex growth rate expected in the simulation. We show that...

  5. Is Dark Energy Abnormally Weighting?

    E-Print Network [OSTI]

    A. Fuzfa; J. -M. Alimi

    2006-09-05

    We present a new interpretation of dark energy in terms of an \\textit{Abnormally Weighting Energy} (AWE). This means that dark energy does not couple to gravitation in the same way as ordinary matter, yielding a violation of the weak and strong equivalence principles on cosmological scales. The resulting cosmological mechanism accounts for the Hubble diagram of type Ia supernovae in terms of both cosmic acceleration and variation of the gravitational constant while still accounting for the present tests of general relativity. This explanation allows to build dark energy models (i) without violation of the strong energy condition $p<-\\rho c^2/3$ (ii) with non-negligible direct couplings to gravitation and (iii) natural convergence mechanism toward general relativity.

  6. Unified dark energy-dark matter model with inverse quintessence

    SciTech Connect (OSTI)

    Ansoldi, Stefano; Guendelman, Eduardo I. E-mail: guendel@bgu.ac.il

    2013-05-01

    We consider a model where both dark energy and dark matter originate from the coupling of a scalar field with a non-canonical kinetic term to, both, a metric measure and a non-metric measure. An interacting dark energy/dark matter scenario can be obtained by introducing an additional scalar that can produce non constant vacuum energy and associated variations in dark matter. The phenomenology is most interesting when the kinetic term of the additional scalar field is ghost-type, since in this case the dark energy vanishes in the early universe and then grows with time. This constitutes an ''inverse quintessence scenario'', where the universe starts from a zero vacuum energy density state, instead of approaching it in the future.

  7. Correspondence between Ricci and other dark energies

    E-Print Network [OSTI]

    Surajit Chattopadhyay; Ujjal Debnath

    2010-09-26

    Purpose of the present paper is to view the correspondence between Ricci and other dark energies. We have considered the Ricci dark energy in presence of dark matter in non-interacting situation. Subsequently, we have derived the pressure and energy density for Ricci dark energy. The equation of state parameter has been generated from these pressure and energy density. Next, we have considered the correspondence between Ricci and other dark energy models, namely tachyonic field, DBI-essence and new agegraphic dark energy without any interaction and investigated possible cosmological consequences.

  8. Dark energy and 3-manifold topology

    E-Print Network [OSTI]

    Torsten Asselmeyer-Maluga; Helge Rose

    2007-11-21

    We show that the differential-geometric description of matter by differential structures of spacetime leads to a unifying model of the three types of energy in the cosmos: matter, dark matter and dark energy. Using this model we are able to calculate the ratio of dark energy to the total energy of the cosmos.

  9. Dark energy and possible alternatives

    E-Print Network [OSTI]

    M. Sami

    2009-01-07

    We present a brief review of various approaches to late time acceleration of universe. The cosmological relevance of scaling solutions is emphasized in case of scalar field models of dark energy. The underlying features of a variety of scalar field models is highlighted. Various alternatives to dark energy are discussed including the string curvature corrections to Einstein-Hilbert action, higher dimensional effects, non-locally corrected gravity and $f(R)$ theories of gravity. The recent developments related to $f(R)$ models with disappearing cosmological constant are reviewed.

  10. Dark energy and possible alternatives

    E-Print Network [OSTI]

    Sami, M

    2009-01-01

    We present a brief review of various approaches to late time acceleration of universe. The cosmological relevance of scaling solutions is emphasized in case of scalar field models of dark energy. The underlying features of a variety of scalar field models is highlighted. Various alternatives to dark energy are discussed including the string curvature corrections to Einstein-Hilbert action, higher dimensional effects, non-locally corrected gravity and $f(R)$ theories of gravity. The recent developments related to $f(R)$ models with disappearing cosmological constant are reviewed.

  11. Freezing Out Early Dark Energy

    E-Print Network [OSTI]

    Jannis Bielefeld; W. L. Kimmy Wu; Robert R. Caldwell; Olivier Dore

    2013-05-09

    A phenomenological model of dark energy that tracks the baryonic and cold dark matter at early times but resembles a cosmological constant at late times is explored. In the transition between these two regimes, the dark energy density drops rapidly as if it were a relic species that freezes out, during which time the equation of state peaks at +1. Such an adjustment in the dark energy density, as it shifts from scaling to potential-domination, could be the signature of a trigger mechanism that helps explain the late-time cosmic acceleration. We show that the non-negligible dark energy density at early times, and the subsequent peak in the equation of state at the transition, leave an imprint on the cosmic microwave background anisotropy pattern and the rate of growth of large scale structure. The model introduces two new parameters, consisting of the present-day equation of state and the redshift of the freeze-out transition. A Monte Carlo Markov Chain analysis of a ten-dimensional parameter space is performed to compare the model with pre-Planck cosmic microwave background, large scale structure and supernova data and measurements of the Hubble constant. We find that the transition described by this model could have taken place as late as a redshift z~400. We explore the capability of future cosmic microwave background and weak lensing experiments to put tighter constraints on this model. The viability of this model may suggest new directions in dark-energy model building that address the coincidence problem.

  12. Power Spectra to 1% Accuracy between Dynamical Dark Energy Cosmologies

    E-Print Network [OSTI]

    Matthew J. Francis; Geraint F. Lewis; Eric V. Linder

    2007-04-03

    For dynamical dark energy cosmologies we carry out a series of N-body gravitational simulations, achieving percent level accuracy in the relative mass power spectra at any redshift. Such accuracy in the power spectrum is necessary for next generation cosmological mass probes. Our matching procedure reproduces the CMB distance to last scattering and delivers subpercent level power spectra at z=0 and z~3. We discuss the physical implications for probing dark energy with surveys of large scale structure.

  13. From Inflation to Dark Energy

    E-Print Network [OSTI]

    Robert Brout

    2005-08-04

    It is proposed that after the macroscopic fluctuation of energy density that is responsible for inflation dies away, a class of microscopic fluctuations, always present, survives to give the present day dark energy. This latter is simply a reinterpretation of the causet mechanism of Ahmed, Dodelson, Green and Sorkin, wherein the emergence of space is dropped but only energy considerations are maintained. At postinflation times, energy is exchanged between the "cisplanckian" cosmos and an unknown foam-like transplanckian reservoir. Whereas during inflation, the energy flows only from the latter to the former after inflation it fluctuates in sign thereby accounting for the tiny effective cosmological constant that seems to account for dark energy.

  14. Accelerated expansion without dark energy

    E-Print Network [OSTI]

    Dominik J. Schwarz

    2002-10-03

    The fact that the LambdaCDM model fits the observations does not necessarily imply the physical existence of `dark energy'. Dropping the assumption that cold dark matter (CDM) is a perfect fluid opens the possibility to fit the data without dark energy. For imperfect CDM, negative bulk pressure is favoured by thermodynamical arguments and might drive the cosmic acceleration. The coincidence between the onset of accelerated expansion and the epoch of structure formation at large scales might suggest that the two phenomena are linked. A specific example is considered in which effective (anti-frictional) forces, which may be due to dissipative processes during the formation of inhomogeneities, give rise to accelerated expansion of a CDM universe.

  15. Separating Dark Physics from Physical Darkness: Minimalist Modified Gravity vs. Dark Energy

    E-Print Network [OSTI]

    Huterer, Dragan

    2009-01-01

    LBNL- 61880 Separating Dark Physics from Physical Darkness:2 Kavli Institute for Cosmological Physics and Astronomy andOffice of High Energy Physics, of the U.S. Department of

  16. Final Technical Report: Discovering the Nature of Dark Energy...

    Office of Scientific and Technical Information (OSTI)

    Report: Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae Saurabh W. Jha 79 ASTRONOMY AND ASTROPHYSICS dark energy; supernovae; cosmology dark...

  17. Holographic dark energy from minimal supergravity

    E-Print Network [OSTI]

    Ricardo C. G. Landim

    2015-10-13

    We embed models of holographic dark energy coupled to dark matter in minimal supergravity plus matter, with one chiral superfield. We analyze two cases. The first one has the Hubble radius as the infrared cutoff and the interaction between the two fluids is proportional to the energy density of the dark energy. The second case has the future event horizon as infrared cutoff while the interaction is proportional to the energy density of both components of the dark sector.

  18. Holographic dark energy from minimal supergravity

    E-Print Network [OSTI]

    Landim, Ricardo C G

    2015-01-01

    We embed models of holographic dark energy coupled to dark matter in minimal supergravity plus matter, with one chiral superfield. We analyze two cases. The first one has the Hubble radius as the infrared cutoff and the interaction between the two fluids is proportional to the energy density of the dark energy. The second case has the future event horizon as infrared cutoff while the interaction is proportional to the energy density of both components of the dark sector.

  19. Complementarity of Future Dark Energy Probes

    E-Print Network [OSTI]

    Jiayu Tang; Filipe B. Abdalla; Jochen Weller

    2008-07-20

    In recent years a plethora of future surveys have been suggested to constrain the nature of dark energy. In this paper we adapt a binning approach to the equation of state factor ``w'' and discuss how future weak lensing, galaxy cluster counts, Supernovae and baryon acoustic oscillation surveys constrain the equation of state at different redshifts. We analyse a few representative future surveys, namely DES, PS1, WFMOS, PS4, EUCLID, SNAP and SKA, and perform a principal component analysis for the ``w'' bins. We also employ a prior from Planck cosmic microwave background measurements on the remaining cosmological parameters. We study at which redshifts a particular survey constrains the equation of state best and how many principal components are significantly determined. We then point out which surveys would be sufficiently complementary. We find that weak lensing surveys, like EUCLID, would constrain the equation of state best and would be able to constrain of the order of three significant modes. Baryon acoustic oscillation surveys on the other hand provide a unique opportunity to probe the equation of state at relatively high redshifts.

  20. Dynamics of dark energy in collapsing halo of dark matter

    E-Print Network [OSTI]

    Tsizh, M

    2015-01-01

    We investigate the non-linear evolution of spherical density and velocity perturbations of dark matter and dark energy in the expanding Universe. For that we have used the conservation and Einstein equations to describe the evolution of gravitationally coupled inhomogeneities of dark matter, dark energy and radiation from linear stage in the early Universe to the non-linear one at the current epoch. The simple method of the numerical integration of the system of non-linear differential equations for evolution of the central part of halo is proposed. The results are presented for halo of cluster ($k=2$ Mpc$^{-1}$) and supercluster scales ($k=0.2$ Mpc$^{-1}$) and show that quintessential scalar field dark energy with small value of effective speed of sound $c_s<0.1$ can give noticeable impact on the formation of large scale structures in the expanding Universe.

  1. The Phase Transition of Dark Energy

    E-Print Network [OSTI]

    Wei Wang; Yuanxing Gui; Ying Shao

    2006-12-05

    Considering that the universe is filled with the nonrelativistic matter and dark energy and each component is respectively satisfied with its conservation condition in the absence of their interaction, we give the change rate of the fractional density and the density of dark energy from the conservation condition. It is clear that the fractional density of dark energy will monotonously increase and gradually become the dominating contribution to the universe as the redshift becomes low. Combining the evolutional trend of the state equation of dark energy and the change rate of the density of dark energy we find that the density of dark energy will decrease up to a minimum and whereafter it will increase again as the redshift becomes low. This can be regarded as the phase transition of dark energy from the quintessence phase to the phantom phase.

  2. BASF's Energy Survey Methodology 

    E-Print Network [OSTI]

    Theising, T. R.

    2005-01-01

    Methodology Thomas R. Theising BASF Corporation operates several dozen manufacturing Sites within NAFTA and periodically conducts Energy Surveys at each Site. Although these manufacturing sites represent a variety of industries, BASF has found success.... The discovery phase is the ?Energy Survey? itself. These Surveys involve plant personnel from various functions within Site operations. BASF applies the Pareto Principle in a variety of fashions: 20% of the operation consumes 80% of the energy, lets focus...

  3. Material models of dark energy

    E-Print Network [OSTI]

    Jonathan A. Pearson

    2014-09-16

    We review and develop a new class of "dark energy" models, in which the relativistic theory of solids is used to construct material models of dark energy. These are models which include the effects of a continuous medium with well defined physical properties at the level of linearized perturbations. The formalism is constructed for a medium with arbitrary symmetry, and then specialised to isotropic media (which will be the case of interest for the majority of cosmological applications). We develop the theory of relativistic isotropic viscoelastic media whilst keeping in mind that we ultimately want to observationally constrain the allowed properties of the material model. We do this by obtaining the viscoelastic equations of state for perturbations (the entropy and anisotropic stress), as well as identifying the consistent corner of the theory which has constant equation of state parameter $\\dot{w}=0$. We also connect to the non-relativistic theory of solids, by identifying the two quadratic invariants that are needed to construct the energy-momentum tensor, namely the Rayleigh dissipation function and Lagrangian for perturbations. Finally, we develop the notion that the viscoelastic behavior of the medium can be thought of as a non-minimally coupled massive gravity theory. This also provides a tool-kit for constructing consistent generalizations of coupled dark energy theories.

  4. Modelling dark energy 

    E-Print Network [OSTI]

    Jackson, Brendan Marc

    2011-11-23

    One of the most pressing, modern cosmological mysteries is the cause of the accelerated expansion of the universe. The energy density required to cause this large scale opposition to gravity is known to be both far in ...

  5. Genesis of Dark Energy: Dark Energy as a Consequence of Cosmological Nuclear Energy

    E-Print Network [OSTI]

    R. C. Gupta

    2004-12-07

    Recent observations on Type-Ia supernovae and low density measurement of matter (including dark matter) suggest that the present day universe consists mainly of repulsive-gravity type exotic-matter with negative-pressure often referred as dark-energy. But the mystery is about the nature of dark-energy and its puzzling questions such as why, how, where & when about the dark- energy are intriguing. In the present paper the author attempts to answer these questions while making an effort to reveal the genesis of dark-energy, and suggests that the cosmological nuclear-binding-energy liberated during primordial nucleo-synthesis remains trapped for long time and then is released free which manifests itself as dark-energy in the universe. It is also explained why for dark energy the parameter w = -2/3. Noting that w=+1for stiff matter and w=+1/3 for radiation; w = - 2/3 is for dark energy, because -1 is due to deficiency of stiff-nuclear-matter and that this binding energy is ultimately released as radiation contributing +1/3, making w = -1 + 1/3 = -2/3. This thus almost solves the dark-energy mystery of negative-pressure & repulsive-gravity. It is concluded that dark-energy is a consequence of released-free nuclear-energy of cosmos. The proposed theory makes several estimates / predictions, which agree reasonably well with the astrophysical constraints & observations.

  6. Dark matter and dark energy from quark bag model

    SciTech Connect (OSTI)

    Brilenkov, Maxim; Eingorn, Maxim; Jenkovszky, Laszlo; Zhuk, Alexander E-mail: maxim.eingorn@gmail.com E-mail: ai.zhuk2@gmail.com

    2013-08-01

    We calculate the present expansion of our Universe endowed with relict colored objects — quarks and gluons — that survived hadronization either as isolated islands of quark-gluon ''nuggets'' or spread uniformly in the Universe. In the first scenario, the QNs can play the role of dark matter. In the second scenario, we demonstrate that uniform colored objects can play the role of dark energy providing the late-time accelerating expansion of the Universe.

  7. Thermodynamics of dark energy interacting with dark matter and radiation

    E-Print Network [OSTI]

    Mubasher Jamil; Emmanuel N. Saridakis; M. R. Setare

    2010-07-18

    We investigate the validity of the generalized second law of thermodynamics, in the cosmological scenario where dark energy interacts with both dark matter and radiation. Calculating separately the entropy variation for each fluid component and for the apparent horizon itself, we show that the generalized second law is always and generally valid, independently of the specific interaction form, of the fluids equation-of-state parameters and of the background geometry.

  8. On the Chemical Potential of Dark Energy

    E-Print Network [OSTI]

    S. H. Pereira

    2008-06-23

    It is widely assumed that the observed universe is accelerating due to the existence of a new fluid component called dark energy. In this article, the thermodynamics consequences of a nonzero chemical potential on the dark energy component is discussed with special emphasis to the phantom fluid case. It is found that if the dark energy fluid is endowed with a negative chemical potential, the phantom field hypothesis becomes thermodynamically consistent with no need of negative temperatures as recently assumed in the literature.

  9. Dark Energy and Dark Matter in Stars Physic

    E-Print Network [OSTI]

    Plamen Fiziev

    2014-11-02

    We present the basic equations and relations for the relativistic static spherically symmetric stars (SSSS) in the model of minimal dilatonic gravity (MDG) which is {\\em locally} equivalent to the f(R) theories of gravity and gives an alternative description of the effects of dark matter and dark energy. The results for the simplest form of the relativistic equation of state (EOS) of neutron matter are represented. Our approach overcomes the well-known difficulties of the physics of SSSS in the f(R) theories of gravity introducing two novel EOS for cosmological energy-pressure densities and dilaton energy-pressure densities, as well as proper boundary conditions.

  10. Schwarzschild black hole in dark energy background

    E-Print Network [OSTI]

    Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh

    2014-09-27

    In this paper we present an exact solution of Einstein's field equations describing the Schwarzschild black hole in dark energy background. It is also regarded as an embedded solution that the Schwarzschild black hole is embedded into the dark energy space producing Schwarzschild-dark energy black hole. It is found that the space-time geometry of Schwarzschild-dark energy solution is non-vacuum Petrov type $D$ in the classification of space-times. We study the energy conditions (like weak, strong and dominant conditions) for the energy-momentum tensor of the Schwarzschild-dark energy solution. We also find that the energy-momentum tensor of the Schwarzschild-dark energy solution violates the strong energy condition due to the negative pressure leading to a repulsive gravitational force of the matter field in the space-time. It is shown that the time-like vector field for an observer in the Schwarzschild-dark energy space is expanding, accelerating, shearing and non-rotating. We investigate the surface gravity and the area of the horizons for the Schwarzschild-dark energy black hole.

  11. Probing Dark Energy with Theory and Observations

    E-Print Network [OSTI]

    de Putter, Roland

    2010-01-01

    since the radiation energy density today is ? r ? 4 · 10 ?want the potential energy density today to be of order V ?in addition to the dark energy density today: ? and ? AE,0 –

  12. Cosmological constraints on superconducting dark energy models

    E-Print Network [OSTI]

    Zoltán Keresztes; László Á. Gergely; Tiberiu Harko; Shi-Dong Liang

    2015-09-01

    We consider cosmological tests of a scalar-vector-tensor gravitational model, in which the dark energy is included in the total action through a gauge invariant, electromagnetic type contribution. The ground state of dark energy, corresponding to a constant potential $V$ is a Bose-Einstein type condensate with spontaneously broken U(1) symmetry. In another words dark energy appears as a massive vector field emerging from a superposition of a massless vector and a scalar field, the latter corresponding to the Goldstone boson. Two particular cosmological models, corresponding to pure electric and pure magnetic type potentials, respectively are confronted with Type IA Supernovae and Hubble parameter data. In the electric case good fit is obtained along a narrow inclined stripe in the $\\Omega _{m}-\\Omega _{V}$ parameter plane, which includes the $\\Lambda $CDM limit. The other points on this admissible region represent superconducting dark energy as a sum of a cosmological constant and a time-evolving contribution. In the magnetic case the cosmological test selects either i) parameter ranges of the superconducting dark energy allowing for the standard baryonic plus dark matter or ii) a unified superconducting dark matter and dark energy model, additionally including only the baryonic sector. The cosmological data is best matched when the matter decouples from both the scalar and vector sectors of dark energy, hence favoring matter conservation as opposed to particle creation in an irreversible process.

  13. Massive Photon and Dark Energy

    E-Print Network [OSTI]

    Kouwn, Seyen; Park, Chan-Gyung

    2015-01-01

    We investigate cosmology of massive electrodynamics and explore the possibility whether massive photon could provide an explanation of the dark energy. The action is given by the scalar-vector-tensor theory of gravity which is obtained by non-minimal coupling of the massive Stueckelberg QED with gravity and its cosmological consequences are studied by paying a particular attention to the role of photon mass. We find that the theory allows cosmological evolution where the radiation- and matter-dominated epochs are followed by a long period of virtually constant dark energy that closely mimics $\\Lambda$CDM model and the main source of the current acceleration is provided by the nonvanishing photon mass governed by the relation $\\Lambda\\sim m^2$. A detailed numerical analysis shows that the nonvanishing photon mass of the order of $\\sim 10^{-34}$ eV is consistent with the current observations. This magnitude is far less than the most stringent limit on the photon mass available so far, which is of the order of $...

  14. Investigating Dark Energy with Black Hole Binaries

    E-Print Network [OSTI]

    Laura Mersini-Houghton; Adam Kelleher

    2009-06-08

    The accelerated expansion of the universe is ascribed to the existence of dark energy. Black holes accretion of dark energy induces a mass change proportional to the energy density and pressure of the background dark energy fluid. The time scale during which the mass of black holes changes considerably is too long relative to the age of the universe, thus beyond detection possibilities. We propose to take advantage of the modified black hole masses for exploring the equation of state $w[z]$ of dark energy, by investigating the evolution of supermassive black hole binaries on a dark energy background. Deriving the signatures of dark energy accretion on the evolution of binaries, we find that dark energy imprints on the emitted gravitational radiation and on the changes in the orbital radius of the binary can be within detection limits for certain supermassive black hole binaries. In this talk I describe how binaries can provide a useful tool in obtaining complementary information on the nature of dark energy, based on the work done with A.Kelleher.

  15. Singularity-free dark energy star

    E-Print Network [OSTI]

    Farook Rahaman; Anil Kumar Yadav; Saibal Ray; Raju Maulick; Ranjan Sharma

    2011-08-25

    We propose a model for an anisotropic dark energy star where we assume that the radial pressure exerted on the system due to the presence of dark energy is proportional to the isotropic perfect fluid matter density. We discuss various physical features of our model and show that the model satisfies all the regularity conditions and stable as well as singularity-free.

  16. Understanding the Fundamental Properties of Dark Matter and Dark Energy in Structure Formation and Cosmology

    SciTech Connect (OSTI)

    Ellis, Richard S.

    2012-09-30

    The program was concerned with developing and verifying the validity of observational methods for constraining the properties of dark matter and dark energy in the Universe.

  17. ASTRONOMY AND ASTROPHYSICS Dark Energy, Type Ia supernovae, radiative

    Office of Scientific and Technical Information (OSTI)

    of Oklahoma Univ. of Oklahoma 79 ASTRONOMY AND ASTROPHYSICS Dark Energy, Type Ia supernovae, radiative transfer, Dark Energy, Type Ia supernovae, radiative transfer, The...

  18. Fitting and forecasting non-linear coupled dark energy

    E-Print Network [OSTI]

    Casas, Santiago; Baldi, Marco; Pettorino, Valeria; Vollmer, Adrian

    2015-01-01

    We consider cosmological models in which dark matter feels a fifth force mediated by the dark energy scalar field, also known as coupled dark energy. Our interest resides in estimating forecasts for future surveys like Euclid when we take into account non-linear effects, relying on new fitting functions that reproduce the non-linear matter power spectrum obtained from N-body simulations. We obtain fitting functions for models in which the dark matter-dark energy coupling is constant. Their validity is demonstrated for all available simulations in the redshift range $z=0-1.6$ and wave modes below $k=10 \\text{h/Mpc}$. These fitting formulas can be used to test the predictions of the model in the non-linear regime without the need for additional computing-intensive N-body simulations. We then use these fitting functions to perform forecasts on the constraining power that future galaxy-redshift surveys like Euclid will have on the coupling parameter, using the Fisher matrix method for galaxy clustering (GC) and w...

  19. From the Dark Matter Universe to the Dark Energy Universe

    E-Print Network [OSTI]

    Burra G. Sidharth

    2008-03-30

    Till the late nineties the accepted cosmological model was that of a Universe that had originated in the Big Bang and was now decelerating under the influence of as yet undetected dark matter, so that it would come to a halt and eventually collapse. In 1997 however, the author had put forward a contra model wherein the Universe was driven by dark energy, essentially the quantum zero point field, and was accelerating with a small cosmological constant. There were other deductions too, all in total agreement with observation. All this got confirmation in 1998 and subsequent observations have reconfirmed the findings.

  20. What We Know About Dark Energy From Supernovae

    ScienceCinema (OSTI)

    Filippenko, Alex [University of California, Berkeley, California, United States

    2010-01-08

    The measured distances of type Ia (white dwarf) supernovae as a function of redshift (z) have shown that the expansion of the Universe is currently accelerating, probably due to the presence of dark energy (X) having a negative pressure. Combining all of the data with existing results from large-scale structure surveys, we find a best fit for Omega M and Omega X of 0.28 and 0.72 (respectively), in excellent agreement with the values derived independently from WMAP measurements of the cosmic microwave background radiation. Thus far, the best-fit value for the dark energy equation-of-state parameter is -1, and its first derivative is consistent with zero, suggesting that the dark energy may indeed be Einstein's cosmological constant.

  1. Fluid Mechanics Explains Cosmology, Dark Matter, Dark Energy, and Life

    E-Print Network [OSTI]

    Carl H. Gibson

    2012-11-02

    Observations of the interstellar medium by the Herschel, Planck etc. infrared satellites throw doubt on standard {\\Lambda}CDMHC cosmological processes to form gravitational structures. According to the Hydro-Gravitational-Dynamics (HGD) cosmology of Gibson (1996), and the quasar microlensing observations of Schild (1996), the dark matter of galaxies consists of Proto-Globular-star-Cluster (PGC) clumps of Earth-mass primordial gas planets in metastable equilibrium since PGCs began star production at 0.3 Myr by planet mergers. Dark energy and the accelerating expansion of the universe inferred from SuperNovae Ia are systematic dimming errors produced as frozen gas dark matter planets evaporate to form stars. Collisionless cold dark matter that clumps and hierarchically clusters does not exist. Clumps of PGCs began diffusion from the Milky Way Proto-Galaxy upon freezing at 14 Myr to give the Magellanic Clouds and the faint dwarf galaxies of the 10^22 m diameter baryonic dark matter Galaxy halo. The first stars persist as old globular star clusters (OGCs). Water oceans and the biological big bang occurred at 2-8 Myr. Life inevitably formed and evolved in the cosmological primordial organic soup provided by 10^80 big bang planets and their hot oceans as they gently merged to form larger binary planets and small binary stars.

  2. Why we need to see the dark matter to understand the dark energy

    E-Print Network [OSTI]

    Martin Kunz

    2007-10-30

    The cosmological concordance model contains two separate constituents which interact only gravitationally with themselves and everything else, the dark matter and the dark energy. In the standard dark energy models, the dark matter makes up some 20% of the total energy budget today, while the dark energy is responsible for about 75%. Here we show that these numbers are only robust for specific dark energy models and that in general we cannot measure the abundance of the dark constituents separately without making strong assumptions.

  3. Phase Space Dynamics of Non-Gravitational Interactions between Dark Matter and Dark Energy: The Case of Ghost Dark Energy

    E-Print Network [OSTI]

    Ricardo Garcia-Salcedo; Tame Gonzalez; Israel Quiros

    2012-11-15

    We study the phase space asymptotics of the so called Veneziano ghost dark energy models. Models where the ghost field's energy density: i) $\\rho_{ghost}\\propto H$, and ii) $\\rho_{ghost}\\propto H+H^2$, are investigated. Both, cases with and without additional non-gravitational interaction between cold dark matter and ghost dark energy, are subject to scrutiny. We pay special attention to the choice of phase space variables leading to bounded and compact phase space so that no critical point of physical interest is missing. A rich asymptotic structure is revealed: depending on the kind of non-minimal coupling critical points associated with radiation dominance, matter dominance, cold dark matter/ghost dark energy scaling, and ghost dark energy dominance, are found. Past and future attractors, as well as saddle equilibrium points, are identified in the corresponding phase spaces.

  4. Nonparametric reconstruction of the dark energy equation of state

    SciTech Connect (OSTI)

    Heitmann, Katrin; Holsclaw, Tracy; Alam, Ujjaini; Habib, Salman; Higdon, David; Sanso, Bruno; Lee, Herbie

    2009-01-01

    The major aim of ongoing and upcoming cosmological surveys is to unravel the nature of dark energy. In the absence of a compelling theory to test, a natural approach is to first attempt to characterize the nature of dark energy in detail, the hope being that this will lead to clues about the underlying fundamental theory. A major target in this characterization is the determination of the dynamical properties of the dark energy equation of state w. The discovery of a time variation in w(z) could then lead to insights about the dynamical origin of dark energy. This approach requires a robust and bias-free method for reconstructing w(z) from data, which does not rely on restrictive expansion schemes or assumed functional forms for w(z). We present a new non parametric reconstruction method for the dark energy equation of state based on Gaussian Process models. This method reliably captures nontrivial behavior of w(z) and provides controlled error bounds. We demollstrate the power of the method on different sets of simulated supernova data. The GP model approach is very easily extended to include diverse cosmological probes.

  5. Dark Energy: Observational Evidence and Theoretical Models

    E-Print Network [OSTI]

    B. Novosyadlyj; V. Pelykh; Yu. Shtanov; A. Zhuk

    2015-02-14

    The book elucidates the current state of the dark energy problem and presents the results of the authors, who work in this area. It describes the observational evidence for the existence of dark energy, the methods and results of constraining of its parameters, modeling of dark energy by scalar fields, the space-times with extra spatial dimensions, especially Kaluza---Klein models, the braneworld models with a single extra dimension as well as the problems of positive definition of gravitational energy in General Relativity, energy conditions and consequences of their violation in the presence of dark energy. This monograph is intended for science professionals, educators and graduate students, specializing in general relativity, cosmology, field theory and particle physics.

  6. Is this the end of dark energy?

    E-Print Network [OSTI]

    Edésio M. Barboza Jr.; Rafael C. Nunes; Éverton M. C. Abreu; Jorge Ananias Neto

    2015-01-13

    In this paper we investigate the limits imposed by thermodynamics to a dark energy fluid. We obtain the heat capacities and the compressibilities for a dark energy fluid. These thermodynamical variables are easily accessible experimentally for any terrestrial fluid. The thermal and mechanical stabilities require these quantities to be positive. We show that such requirements forbid the existence of a cosmic fluid with negative constant EoS parameter which excludes vacuum energy as a candidate to explain the cosmic acceleration. We also show that the current observational data from SN Ia, BAO and $H(z)$ are in conflict with the physical constraints that a general dark energy fluid with a time-dependent EoS parameter must obey which can be interpreted as an evidence against the dark energy hypothesis. Although our result excludes the vacuum energy, a geometrical cosmological term as originally introduced by Einstein in the field equations remains untouched.

  7. Is this the end of dark energy?

    E-Print Network [OSTI]

    Barboza, Edésio M; Abreu, Éverton M C; Neto, Jorge Ananias

    2015-01-01

    In this paper we investigate the limits imposed by thermodynamics to a dark energy fluid. We obtain the heat capacities and the compressibilities for a dark energy fluid. These thermodynamical variables are easily accessible experimentally for any terrestrial fluid. The thermal and mechanical stabilities require these quantities to be positive. We show that such requirements forbid the existence of a cosmic fluid with negative constant EoS parameter which excludes vacuum energy as a candidate to explain the cosmic acceleration. We also show that the current observational data from SN Ia, BAO and $H(z)$ are in conflict with the physical constraints that a general dark energy fluid with a time-dependent EoS parameter must obey which can be interpreted as an evidence against the dark energy hypothesis. Although our result excludes the vacuum energy, a geometrical cosmological term as originally introduced by Einstein in the field equations remains untouched.

  8. Is Hubble's Expansion due to Dark Energy

    E-Print Network [OSTI]

    R. C. Gupta; Anirudh Pradhan

    2010-10-19

    {\\it The universe is expanding} is known (through Galaxy observations) since 1929 through Hubble's discovery ($V = H D$). Recently in 1999, it is found (through Supernovae observations) that the universe is not simply expanding but is accelerating too. We, however, hardly know only $4\\%$ of the universe. The Wilkinson Microwave Anisotropy Probe (WMAP) satellite observational data suggest $73\\%$ content of the universe in the form of dark-energy, $23\\%$ in the form of non-baryonic dark-matter and the rest $4\\%$ in the form of the usual baryonic matter. The acceleration of the universe is ascribed to this dark-energy with bizarre properties (repulsive-gravity). The question is that whether Hubble's expansion is just due to the shock of big-bang & inflation or it is due to the repulsive-gravity of dark-energy? Now, it is believed to be due to dark-energy, say, by re-introducing the once-discarded cosmological-constant $\\Lambda$. In the present paper, it is shown that `the formula for acceleration due to dark-energy' is (almost) exactly of same-form as `the acceleration formula from the Hubble's law'. Hence, it is concluded that: yes, `indeed it is the dark-energy responsible for the Hubble's expansion too, in-addition to the current on-going acceleration of the universe'.

  9. Cosmological constraints on superconducting dark energy models

    E-Print Network [OSTI]

    Keresztes, Zoltán; Harko, Tiberiu; Liang, Shi-Dong

    2015-01-01

    We consider cosmological tests of a scalar-vector-tensor gravitational model, in which the dark energy is included in the total action through a gauge invariant, electromagnetic type contribution. The ground state of dark energy, corresponding to a constant potential $V$ is a Bose-Einstein type condensate with spontaneously broken U(1) symmetry. In another words dark energy appears as a massive vector field emerging from a superposition of a massless vector and a scalar field, the latter corresponding to the Goldstone boson. Two particular cosmological models, corresponding to pure electric and pure magnetic type potentials, respectively are confronted with Type IA Supernovae and Hubble parameter data. In the electric case good fit is obtained along a narrow inclined stripe in the $\\Omega _{m}-\\Omega _{V}$ parameter plane, which includes the $\\Lambda $CDM limit. The other points on this admissible region represent superconducting dark energy as a sum of a cosmological constant and a time-evolving contribution...

  10. Brane-Bulk energy exchange and agegraphic dark energy

    E-Print Network [OSTI]

    Ahmad Sheykhi

    2010-02-06

    We consider the agegraphic models of dark energy in a braneworld scenario with brane-bulk energy exchange. We assume that the adiabatic equation for the dark matter is satisfied while it is violated for the agegraphic dark energy due to the energy exchange between the brane and the bulk. Our study shows that with the brane-bulk interaction, the equation of state parameter of agegraphic dark energy on the brane, $w_D$, can have a transition from normal state where $w_D >-1 $ to the phantom regime where $w_D energy always satisfies $w^{\\mathrm{eff}}_D\\geq-1$.

  11. MAPPING THE DARK MATTER WITH POLARIZED RADIO SURVEYS

    SciTech Connect (OSTI)

    Brown, Michael L.; Battye, Richard A.

    2011-07-01

    In a recent paper, we proposed the use of integrated polarization measurements of background galaxies in radio weak gravitational lensing surveys and investigated the potential impact on the statistical measurement of cosmic shear. Here we extend this idea to reconstruct maps of the projected dark matter distribution or lensing convergence field. The addition of polarization can, in principle, greatly reduce shape noise due to the intrinsic dispersion in galaxy ellipticities. We show that maps reconstructed using this technique in the radio band can be competitive with those derived using standard lensing techniques which make use of many more galaxies. In addition, since the reconstruction noise is uncorrelated between these standard techniques and the polarization technique, their comparison can serve as a powerful check for systematics and their combination can reduce noise further. We examine the convergence reconstruction which could be achieved with two forthcoming facilities: (1) a deep survey, covering 1.75 deg{sup 2} using the e-MERLIN instrument currently being commissioned in the UK and (2) the high-resolution, deep wide-field surveys which will eventually be conducted with the Square Kilometre Array.

  12. Interacting agegraphic dark energy models in non-flat universe

    E-Print Network [OSTI]

    Ahmad Sheykhi

    2009-09-12

    A so-called "agegraphic dark energy" was recently proposed to explain the dark energy-dominated universe. In this Letter, we generalize the agegraphic dark energy models to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We show that these models can accommodate $w_D = -1 $ crossing for the equation of state of dark energy. In the limiting case of a flat universe, i.e. $k = 0$, all previous results of agegraphic dark energy in flat universe are restored.

  13. Cosmic Acceleration, Dark Energy and Fundamental Physics

    E-Print Network [OSTI]

    Michael S. Turner; Dragan Huterer

    2007-06-26

    A web of interlocking observations has established that the expansion of the Universe is speeding up and not slowing, revealing the presence of some form of repulsive gravity. Within the context of general relativity the cause of cosmic acceleration is a highly elastic (p\\sim -rho), very smooth form of energy called ``dark energy'' accounting for about 75% of the Universe. The ``simplest'' explanation for dark energy is the zero-point energy density associated with the quantum vacuum; however, all estimates for its value are many orders-of-magnitude too large. Other ideas for dark energy include a very light scalar field or a tangled network of topological defects. An alternate explanation invokes gravitational physics beyond general relativity. Observations and experiments underway and more precise cosmological measurements and laboratory experiments planned for the next decade will test whether or not dark energy is the quantum energy of the vacuum or something more exotic, and whether or not general relativity can self consistently explain cosmic acceleration. Dark energy is the most conspicuous example of physics beyond the standard model and perhaps the most profound mystery in all of science.

  14. A Casimir approach to dark energy

    E-Print Network [OSTI]

    Allan Rosencwaig

    2006-06-26

    We calculate the gravitational self-energy of vacuum quantum field fluctuations using a Casimir approach. We find that the Casimir gravitational self-energy density can account for the measured dark energy density when the SUSY-breaking energy is approximately 5 TeV, in good agreement with current estimates. Furthermore, the Casimir gravitational self-energy appears to provide a quantum mechanism for the well-know geometric relation between the Planck, SUSY and cosmological constant energy scales.

  15. Falsification of dark energy by fluid mechanics

    E-Print Network [OSTI]

    Carl H. Gibson

    2012-03-23

    The 2011 Nobel Prize in Physics was awarded for the discovery of accelerating supernovae dimness, suggesting a remarkable change in the expansion rate of the Universe from a decrease since the big bang to an increase, driven by anti-gravity forces of a mysterious dark energy material comprising 70% of the Universe mass-energy. Fluid mechanical considerations falsify both the accelerating expansion and dark energy concepts. Kinematic viscosity is neglected in current standard models of self-gravitational structure formation, which rely on cold dark matter CDM condensations and clusterings that are also falsified by fluid mechanics. Weakly collisional CDM particles do not condense but diffuse away. Photon viscosity predicts superclustervoid fragmentation early in the plasma epoch and protogalaxies at the end. At the plasma-gas transition, the plasma fragments into Earth-mass gas planets in trillion planet clumps (proto-globular-star-cluster PGCs). The hydrogen planets freeze to form the dark matter of galaxies and merge to form their stars. Dark energy is a systematic dimming error for Supernovae Ia caused by dark matter planets near hot white dwarf stars at the Chandrasekhar carbon limit. Evaporated planet atmospheres may or may not scatter light from the events depending on the line of sight.

  16. Conformal Higgs model: predicted dark energy density

    E-Print Network [OSTI]

    R. K. Nesbet

    2014-11-03

    Postulated universal Weyl conformal scaling symmetry provides an alternative to the $\\Lambda$CDM paradigm for cosmology. Recent applications to galactic rotation velocities, Hubble expansion, and a model of dark galactic halos explain qualitative phenomena and fit observed data without invoking dark matter. Significant revision of theory relevant to galactic collisions and clusters is implied, but not yet tested. Dark energy is found to be a consequence of conformal symmetry for the Higgs scalar field of electroweak physics. The present paper tests this implication. The conformal Higgs model acquires a gravitational effect described by a modified Friedmann cosmic evolution equation, shown to fit cosmological data going back to the cosmic microwave background epoch. The tachyonic mass parameter of the Higgs model becomes dark energy in the Friedmann equation. A dynamical model of this parameter, analogous to the Higgs mechanism for gauge boson mass, is derived and tested here. An approximate calculation yields a result consistent with the empirical magnitude inferred from Hubble expansion.

  17. Dark goo: Bulk viscosity as an alternative to dark energy

    E-Print Network [OSTI]

    Jean-Sebastien Gagnon; Julien Lesgourgues

    2011-09-16

    We present a simple (microscopic) model in which bulk viscosity plays a role in explaining the present acceleration of the universe. The effect of bulk viscosity on the Friedmann equations is to turn the pressure into an "effective" pressure containing the bulk viscosity. For a sufficiently large bulk viscosity, the effective pressure becomes negative and could mimic a dark energy equation of state. Our microscopic model includes self-interacting spin-zero particles (for which the bulk viscosity is known) that are added to the usual energy content of the universe. We study both background equations and linear perturbations in this model. We show that a dark energy behavior is obtained for reasonable values of the two parameters of the model (i.e. the mass and coupling of the spin-zero particles) and that linear perturbations are well-behaved. There is no apparent fine tuning involved. We also discuss the conditions under which hydrodynamics holds, in particular that the spin-zero particles must be in local equilibrium today for viscous effects to be important.

  18. Dark goo: Bulk viscosity as an alternative to dark energy

    E-Print Network [OSTI]

    Gagnon, Jean-Sebastien

    2011-01-01

    We present a simple (microscopic) model in which bulk viscosity plays a role in explaining the present acceleration of the universe. The effect of bulk viscosity on the Friedmann equations is to turn the pressure into an "effective" pressure containing the bulk viscosity. For a sufficiently large bulk viscosity, the effective pressure becomes negative and could mimic a dark energy equation of state. Our microscopic model includes self-interacting spin-zero particles (for which the bulk viscosity is known) that are added to the usual energy content of the universe. We study both background equations and linear perturbations in this model. We show that a dark energy behavior is obtained for reasonable values of the two parameters of the model (i.e. the mass and coupling of the spin-zero particles) and that linear perturbations are well-behaved. There is no apparent fine tuning involved. We also discuss the conditions under which hydrodynamics holds, in particular that the spin-zero particles must be in local eq...

  19. Cooling the dark energy camera instrument

    SciTech Connect (OSTI)

    Schmitt, R.L.; Cease, H.; DePoy, D.; Diehl, H.T.; Estrada, J.; Flaugher, B.; Kuhlmann, S.; Onal, Birce; Stefanik, A.; /Fermilab

    2008-06-01

    DECam, camera for the Dark Energy Survey (DES), is undergoing general design and component testing. For an overview see DePoy, et al in these proceedings. For a description of the imager, see Cease, et al in these proceedings. The CCD instrument will be mounted at the prime focus of the CTIO Blanco 4m telescope. The instrument temperature will be 173K with a heat load of 113W. In similar applications, cooling CCD instruments at the prime focus has been accomplished by three general methods. Liquid nitrogen reservoirs have been constructed to operate in any orientation, pulse tube cryocoolers have been used when tilt angles are limited and Joule-Thompson or Stirling cryocoolers have been used with smaller heat loads. Gifford-MacMahon cooling has been used at the Cassegrain but not at the prime focus. For DES, the combined requirements of high heat load, temperature stability, low vibration, operation in any orientation, liquid nitrogen cost and limited space available led to the design of a pumped, closed loop, circulating nitrogen system. At zenith the instrument will be twelve meters above the pump/cryocooler station. This cooling system expected to have a 10,000 hour maintenance interval. This paper will describe the engineering basis including the thermal model, unbalanced forces, cooldown time, the single and two-phase flow model.

  20. Alternative Dark Energy Models: An Overview

    E-Print Network [OSTI]

    J. A. S. Lima

    2004-02-04

    A large number of recent observational data strongly suggest that we live in a flat, accelerating Universe composed of $\\sim$ 1/3 of matter (baryonic + dark) and $\\sim$ 2/3 of an exotic component with large negative pressure, usually named {\\bf Dark Energy} or {\\bf Quintessence}. The basic set of experiments includes: observations from SNe Ia, CMB anisotropies, large scale structure, X-ray data from galaxy clusters, age estimates of globular clusters and old high redshift galaxies (OHRG's). Such results seem to provide the remaining piece of information connecting the inflationary flatness prediction ($\\Omega_{\\rm{T}} = 1$) with astronomical observations. Theoretically, they have also stimulated the current interest for more general models containing an extra component describing this unknown dark energy, and simultaneously accounting for the present accelerating stage of the Universe. An overlook in the literature shows that at least five dark energy candidates have been proposed in the context of general relativistic models. Since the cosmological constant and rolling scalar field models have already been extensively discussed, in this short review we focus our attention to the three remaining candidates, namely: a decaying vacuum energy density (or ${\\bf \\Lambda(t)}$ {\\bf models}), the {\\bf X-matter}, and the so-called {\\bf Chaplygin-type gas}. A summary of their main results is given and some difficulties underlying the emerging dark energy paradigm are also briefly examined.

  1. Dark Energy Density in Brane World

    E-Print Network [OSTI]

    Hai-Bao Wen; Xin-Bing Huang

    2005-02-08

    We present a possible explanation to the tiny positive cosmological constant under the frame of AdS$_5$ spacetime embedded by a dS$_4$ brane. We calculate the dark energy density by summing the zero point energy of massive scalar fields in AdS$_5$ spacetime. Under the assumption that the radius of AdS$_5$ spacetime is of the same magnitude as the radius of observable universe, the dark energy density in dS$_4$ brane is obtained, which is smaller than the observational value. The reasons are also discussed.

  2. Gravitoelectromagnetism and Dark Energy in Superconductors

    E-Print Network [OSTI]

    Clovis Jacinto de Matos

    2006-07-03

    A gravitomagnetic analogue of the London moment in superconductors can explain the anomalous Cooper pair mass excess reported by Janet Tate. Ultimately the gravitomagnetic London moment is attributed to the breaking of the principle of general covariance in superconductors. This naturally implies non-conservation of classical energy-momentum. Possible relation with the manifestation of dark energy in superconductors is questioned.

  3. Wiggly cosmic strings accrete dark energy

    E-Print Network [OSTI]

    Pedro F. Gonzalez-Diaz; Jose A. Jimenez Madrid

    2005-06-29

    This paper deals with a study of the cylindrically symmetric accretion of dark energy with equation of state $p=w\\rho$ onto wiggly straight cosmic strings. We have obtained that when $w>-1$ the linear energy density in the string core gradually increases tending to a finite maximum value as time increases for all considered dark energy models. On the regime where the dominant energy condition is violated all such models predict a steady decreasing of the linear energy density of the cosmic strings as phantom energy is being accreted. The final state of the string after such an accretion process is a wiggleless defect. It is argued however that if accreation of phantom energy would proceed by successive quantum steps then the defect would continue losing linear energy density until a minimum nonzero value which can be quite smaller than that corresponding to the unperturbed string.

  4. Dark matter interacts with variable vacuum energy

    E-Print Network [OSTI]

    Iván E. Sánchez G

    2014-09-21

    We investigate a spatially flat Friedmann-Robertson-Walker (FRW) scenario with two interacting components, dark matter and variable vacuum energy (VVE) densities, plus two decoupled components, one is a baryon term while the other behaves as a radiation component. We consider a linear interaction in the derivative dark component density. We apply the $\\chi^2$ method to the observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era for the model. It turns out that our model fulfills the severe bound of $\\Omega_{x}(z\\simeq 1100)energy at early times, and fulfills the stringent bound $\\Omega_{x}(z\\simeq 10^{10})today.

  5. Dark Energy and Life's Ultimate Future

    E-Print Network [OSTI]

    Ruediger Vaas

    2007-03-19

    The discovery of the present accelerated expansion of space changed everything regarding cosmology and life's ultimate prospects. Both the optimistic scenarios of an ever (but decelerated) expanding universe and of a collapsing universe seem to be no longer available. The final future looks deadly dark. However, the fate of the universe and intelligence depends crucially on the nature of the still mysterious dark energy which drives the accelerated expansion. Depending on its - perhaps time-dependent - equation of state, there is a confusing number of different models now, popularly called Big Rip, Big Whimper, Big Decay, Big Crunch, Big Brunch, Big Splat, etc. This paper briefly reviews possibilities and problems. It also argues that even if our universe is finally doomed, perhaps that doesn't matter ultimately because there might be some kind of eternal recurrence. - Key words: Cosmology, Universe, Dark Energy, Cosmological Constant, Quintessence, Phantom Energy, Inflation, Quantum Gravity, Far Future, Life, Intelligence

  6. Viscous dark energy and generalized second law of thermodynamics

    E-Print Network [OSTI]

    M. R. Setare; A. Sheykhi

    2011-03-05

    We examine the validity of the generalized second law of thermodynamics in a non-flat universe in the presence of viscous dark energy. At first we assume that the universe filled only with viscous dark energy. Then, we extend our study to the case where there is an interaction between viscous dark energy and pressureless dark matter. We examine the time evolution of the total entropy, including the entropy associated with the apparent horizon and the entropy of the viscous dark energy inside the apparent horizon. Our study show that the generalized second law of thermodynamics is always protected in a universe filled with interacting viscous dark energy and dark matter in a region enclosed by the apparent horizon. Finally, we show that the the generalized second law of thermodynamics is fulfilled for a universe filled with interacting viscous dark energy and dark matter in the sense that we take into account the Casimir effect.

  7. Dark Energy: A Crisis for Fundamental Physics

    ScienceCinema (OSTI)

    Stubbs, Christopher [Harvard University, Cambridge, Massachusetts, USA

    2010-09-01

    Astrophysical observations provide robust evidence that our current picture of fundamental physics is incomplete. The discovery in 1998 that the expansion of the Universe is accelerating (apparently due to gravitational repulsion between regions of empty space!) presents us with a profound challenge, at the interface between gravity and quantum mechanics. This "Dark Energy" problem is arguably the most pressing open question in modern fundamental physics. The first talk will describe why the Dark Energy problem constitutes a crisis, with wide-reaching ramifications. One consequence is that we should probe our understanding of gravity at all accessible scales, and the second talk will present experiments and observations that are exploring this issue.

  8. The Higgs portal and an unified model for dark energy and dark matter

    E-Print Network [OSTI]

    O. Bertolami; R. Rosenfeld

    2007-08-22

    We examine a scenario where the Higgs boson is coupled to an additional singlet scalar field which we identify with a quintessence field. We show that this results in an unified picture of dark matter and dark energy, where dark energy is the zero-mode classical field rolling the usual quintessence potential and the dark matter candidate is the quantum excitation (particle) of the field, which is produced in the universe due to its coupling to the Higgs boson.

  9. Can Holographic dark energy increase the mass of the wormhole?

    E-Print Network [OSTI]

    Surajit Chattopadhyay; Davood Momeni; Aziza Altaibayeva; Ratbay Myrzakulov

    2014-11-26

    In this work, we have studied accretion of dark energy (DE) onto Morris- Thorne wormhole with three different forms, namely, holographic dark energy, holographic Ricci dark energy and modified holographic Ricci dark energy . Considering the scale factor in power-law form we have observed that as the holographic dark energy accretes onto wormhole, the mass of the wormhole is decreasing. In the next phase we considered three parameterization schemes that are able to get hold of quintessence as well as phantom phases. Without any choice of scale factor we reconstructed Hubble parameter from conservation equation and dark energy densities and subsequently got the mass of the wormhole separately for accretion of the three dark energy candidates. It was observed that if these dark energies accrete onto the wormhole, then for quintessence stage, wormhole mass decreases up to a certain finite value and then again increases to aggressively during phantom phase of the universe.

  10. Dark matter, dark energy, and dark radiation coupled with a transversal interaction

    E-Print Network [OSTI]

    Luis P. Chimento; Martín G. Richarte

    2012-10-19

    We investigate a cosmological scenario with three interacting components that includes dark matter, dark energy, and radiation in the spatially flat Friedmann-Robertson-Walker universe. We introduce a 3-dimensional internal space, the interaction vector $\\mathbf{Q}=(Q_{x}, Q_{m}, Q_{r})$ satisfying the constraint plane $Q_{x}+ Q_{m}+ Q_{r}=0$, the barotropic index vector $ \\boldmath ${\\gamma}$=(\\ga_x,\\ga_m,\\ga_r)$ and select a transversal interaction vector $\\mathbf{Q_t}$ in a sense that $\\mathbf{Q_t}\\cdot \\boldmath ${\\gamma}$=0$. We exactly solve the source equation for a linear $\\mathbf{Q_t}$, that depends on the total energy density and its derivatives up to third order, and find all the component energy densities. We obtain a large set of interactions for which the source equation admits a power law solution and show its asymptotic stability by constructing the Lyapunov function. We apply the $\\chi^{2}$ method to the observational Hubble data for constraining the cosmic parameters, and analyze the amount of dark energy in the radiation era for the above linear $\\mathbf{Q_t}$. It turns to be that our model fulfills the severe bound of $\\Omega_{x}(z\\simeq 1100)<0.1$ and is consistent with the future constraints achievable by Planck and CMBPol experiments.

  11. A Brief History of Dark Energy

    E-Print Network [OSTI]

    C Sivaram

    2008-09-19

    Gurzadyan-Xue Dark Energy was derived in 1986 (twenty years before the paper of Gurzadyan-Xue). The paper by the present author, titled The Planck Length as a Cosmological Constant, published in Astrophysics Space Science, Vol. 127, p.133-137, 1986 contains the formula claimed to have been derived by Gurzadyan-Xue (in 2003).

  12. Using Newton's Law for Dark Energy

    E-Print Network [OSTI]

    Paul Frampton

    2012-09-24

    A model is introduced in which Newton's law is modified between matter and dark energy corpuscles (DECs). The model predicts that the DEC component is presently decelerating in its expansion at 14% of the magnitude of the matter expansion acceleration. In the future, expansion of the DEC universe will continue to decelerate.

  13. Residential Energy Consumption Survey Results: Total Energy Consumptio...

    Open Energy Info (EERE)

    Residential Energy Consumption Survey Results: Total Energy Consumption, Expenditures, and Intensities (2005) The Residential Energy Consumption Survey (RECS) is a national survey...

  14. Cosmic inflation, deceleration, acceleration, dark matter, and dark `energy' in one coherent package

    E-Print Network [OSTI]

    Ellis, Homer

    Cosmic inflation, deceleration, acceleration, dark matter, and dark `energy' in one coherent to (mis)represent a uniform negative net mass density of gravitationally attractive and gravitationally, baryonic particles of primordial matter and as the continuously created, invisible particles of the `dark

  15. On the similarity of Information Energy to Dark Energy

    E-Print Network [OSTI]

    M. P. Gough; T. D. Carozzi; A. M. Buckley

    2006-06-19

    Information energy is shown here to have properties similar to those of dark energy. The energy associated with each information bit of the universe is found to be defined identically to the characteristic energy of a cosmological constant. Two independent methods are used to estimate the universe information content of ~10^91 bits, a value that provides an information energy total comparable to that of the dark energy. Information energy is also found to have a significantly negative equation of state parameter, w energy.

  16. Coupled dark energy: a dynamical analysis with complex scalar field

    E-Print Network [OSTI]

    Ricardo C. G. Landim

    2015-07-01

    The dynamical analysis for coupled dark energy with dark matter is presented, where a complex scalar field is taken into account and it is considered in the presence of a barothropic fluid. We consider three dark energy candidates: quintessence, phantom and tachyon. The critical points are found and their stabilities analyzed, leading to the three cosmological eras (radiation, matter and dark energy), for a generic potential. The results presented here enlarge the previous analyses found in the literature.

  17. An Alternative Approach to Holographic Dark Energy

    E-Print Network [OSTI]

    Simpson, F

    2006-01-01

    We outline a scenario in which dark energy is associated with the particle horizon. An energy density related to the area of the particle horizon is found to behave in accordance with current observational constraints. The equation of state drops as the particle horizon traverses a closed universe. Depending on the constant of proportionality, either the ensuing inflationary period prevents the particle horizon from vanishing, or it may lead to a sequence of "Big Rips".

  18. The Dark Energy Star and Stability analysis

    E-Print Network [OSTI]

    Piyali Bhar; Farook Rahaman

    2015-01-12

    We have proposed a new model of dark energy star consisting of five zones namely, solid core of constant energy density, the thin shell between core and interior, an inhomogeneous interior region with anisotropic pressures, thin shell and the exterior vacuum region. We have discussed various physical properties. The model satisfies all the physical requirements. The stability condition under small linear perturbation has also been discussed.

  19. Detecting dark energy with wavelets on the sphere

    E-Print Network [OSTI]

    J. D. McEwen

    2007-08-29

    Dark energy dominates the energy density of our Universe, yet we know very little about its nature and origin. Although strong evidence in support of dark energy is provided by the cosmic microwave background, the relic radiation of the Big Bang, in conjunction with either observations of supernovae or of the large scale structure of the Universe, the verification of dark energy by independent physical phenomena is of considerable interest. We review works that, through a wavelet analysis on the sphere, independently verify the existence of dark energy by detecting the integrated Sachs-Wolfe effect. The effectiveness of a wavelet analysis on the sphere is demonstrated by the highly statistically significant detections of dark energy that are made. Moreover, the detection is used to constrain properties of dark energy. A coherent picture of dark energy is obtained, adding further support to the now well established cosmological concordance model that describes our Universe.

  20. The coincidence problem and interacting holographic dark energy

    SciTech Connect (OSTI)

    Karwan, Khamphee

    2008-05-15

    We study the dynamical behaviour of the interacting holographic dark energy model whose interaction term is Q = 3H({lambda}{sub d}{rho}{sub d}+{lambda}{sub c}{rho}{sub c}), where {rho}{sub d} and {rho}{sub c} are the energy densities of dark energy and cold dark matter respectively. To satisfy the observational constraints from type Ia supernovae, the cosmic microwave background shift parameter and baryon acoustic oscillation measurements, if {lambda}{sub c} = {lambda}{sub d} or {lambda}{sub d},{lambda}{sub c}>0, the cosmic evolution will only reach the attractor in the future and the ratio {rho}{sub c}/{rho}{sub d} cannot be slowly varying at present. Since the cosmic attractor can be reached in the future even when the present values of the cosmological parameters do not satisfy the observational constraints, the coincidence problem is not really alleviated in this case. However, if {lambda}{sub c}{ne}{lambda}{sub d} and they are allowed to be negative, the ratio {rho}{sub c}/{rho}{sub d} can be slowly varying at present and the cosmic attractor can be reached near the present epoch. Hence, the alleviation of the coincidence problem is attainable in this case. The alleviation of the coincidence problem in this case is still attainable when confronting this model with Sloan Digital Sky Survey data.

  1. Dark energy constraints from lensing-detected galaxy clusters

    E-Print Network [OSTI]

    Laura Marian; Gary M. Bernstein

    2006-05-31

    We study the ability of weak lensing surveys to detect galaxy clusters and constrain cosmological parameters, in particular the equation of state of dark energy. There are two major sources of noise for weak lensing cluster measurements: the ``shape noise'' from the intrinsic ellipticities of galaxies; and the large scale projection noise. We produce a filter for the shear field which optimizes the signal-to-noise of shape-noise-dominated shear measurements. Our Fisher-matrix analysis of this projected-mass observable makes use of the shape of this mass function, and takes into account the Poisson variance, sample variance, shape noise, and projected-mass noise, and also the fact that the conversion of the shear signal into mass is cosmology-dependent. The Fisher analysis is applied to both a nominal 15,000 square degree ground-based survey and a 1000 square degree space-based survey. Assuming a detection threshold of S/N=5, we find both experiments detect \\~20,000 clusters, and yield 1-sigma constraints of ~0.07 for w0 and ~0.2 for wa when combined with CMB data (for flat universe). The projection noise exceeds the shape noise only for clusters at z<=0.1 and has little effect on the derived dark-energy constraints. Sample variance does not significantly affect either survey. Finally, we note that all these results are extremely sensitive to the noise levels and detection thresholds that we impose. They can be significantly improved if we combine ground and space surveys as independent experiments and add their corresponding Fisher matrices.

  2. Influences of Dark Energy and dark matter on Gravitational Time Advancement

    E-Print Network [OSTI]

    Ghosh, Samrat

    2015-01-01

    The effect of dark matter/energy on gravitational time advancement (negative effective time delay) has been investigated considering few dark energy/matter models including cosmological constant. It is found that dark energy gives only (positive) gravitational time delay irrespective of the position of the observer whereas pure Schwarzschild geometry leads to gravitational time advancement when the observer is situated at relatively stronger gravitational field point in the light trajectory. Consequently, there will be no time advancement effect at all at radial distances where gravitational field due to dark energy is stronger than the gravitational field of Schwarzschild geometry.

  3. Genesis of Dark Energy: Dark Energy as Consequence of Release and Two-stage Tracking Cosmological Nuclear Energy

    E-Print Network [OSTI]

    R. C. Gupta; Anirudh Pradhan

    2009-07-28

    Recent observations on Type-Ia supernovae and low density ($\\Omega_{m} = 0.3$) measurement of matter including dark matter suggest that the present-day universe consists mainly of repulsive-gravity type `exotic matter' with negative-pressure often said `dark energy' ($\\Omega_{x} = 0.7$). But the nature of dark energy is mysterious and its puzzling questions, such as why, how, where and when about the dark energy, are intriguing. In the present paper the authors attempt to answer these questions while making an effort to reveal the genesis of dark energy and suggest that `the cosmological nuclear binding energy liberated during primordial nucleo-synthesis remains trapped for a long time and then is released free which manifests itself as dark energy in the universe'. It is also explained why for dark energy the parameter $w = - {2/3}$. Noting that $ w = 1$ for stiff matter and $w = {1/3}$ for radiation; $w = - {2/3}$ is for dark energy because $"-1"$ is due to `deficiency of stiff-nuclear-matter' and that this binding energy is ultimately released as `radiation' contributing $"+ {1/3}"$, making $w = -1 + {1/3} = - {2/3}$. When dark energy is released free at $Z = 80$, $w = -{2/3}$. But as on present day at $Z = 0$ when radiation strength has diminished to $\\delta \\to 0$, $w = -1 + \\delta{1/3} = - 1$. This, thus almost solves the dark-energy mystery of negative pressure and repulsive-gravity. The proposed theory makes several estimates /predictions which agree reasonably well with the astrophysical constraints and observations. Though there are many candidate-theories, the proposed model of this paper presents an entirely new approach (cosmological nuclear energy) as a possible candidate for dark energy.

  4. Present and future evidence for evolving dark energy

    E-Print Network [OSTI]

    Andrew R Liddle; Pia Mukherjee; David Parkinson; Yun Wang

    2006-12-04

    We compute the Bayesian evidences for one- and two-parameter models of evolving dark energy, and compare them to the evidence for a cosmological constant, using current data from Type Ia supernova, baryon acoustic oscillations, and the cosmic microwave background. We use only distance information, ignoring dark energy perturbations. We find that, under various priors on the dark energy parameters, LambdaCDM is currently favoured as compared to the dark energy models. We consider the parameter constraints that arise under Bayesian model averaging, and discuss the implication of our results for future dark energy projects seeking to detect dark energy evolution. The model selection approach complements and extends the figure-of-merit approach of the Dark Energy Task Force in assessing future experiments, and suggests a significantly-modified interpretation of that statistic.

  5. How CMB and large-scale structure constrain chameleon interacting dark energy

    E-Print Network [OSTI]

    Daniel Boriero; Subinoy Das; Yvonne Y. Y. Wong

    2015-05-12

    We explore a chameleon type of interacting dark matter-dark energy scenario in which a scalar field adiabatically traces the minimum of an effective potential sourced by the dark matter density. We discuss extensively the effect of this coupling on cosmological observables, especially the parameter degeneracies expected to arise between the model parameters and other cosmological parameters, and then test the model against observations of the cosmic microwave background (CMB) anisotropies and other cosmological probes. We find that the chameleon parameters $\\alpha$ and $\\beta$, which determine respectively the slope of the scalar field potential and the dark matter-dark energy coupling strength, can be constrained to $\\alpha radiation component, despite a passing similarity between the two scenarios in that they both delay the epoch of matter-radiation equality. Based on the derived parameter constraints, we discuss possible signatures of the model for ongoing and future large-scale structure surveys.

  6. Dark Energy and Search for the Generalized Second Law

    E-Print Network [OSTI]

    Balendra Kr. Dev Choudhury; Julie Saikia

    2009-06-03

    The discovery of accelerated Hubble expansion in the SNIa data and the observed power spectrum of the microwave background radiation provide an ample support for Dark energy and Dark matter. Except for the so far well-known facts that cold dark matter (or simply dark matter) is pressureless, and dark energy has a negative pressure, the nature of these two still remains a complete mystery. The mystery facilitates different consideration. In one hand, dark matter and dark energy are assumed as distinct entities, and other interpretation is that both are different manifestation of a common structure, often referred as quartessence. Chaplygin gas, a perfect fluid also favours the second interpretation. Here, we consider modified chaplygin gas as dark energy candidate. Taking into account the existence of the observer's event horizon in accelerated universe, we find the condition where the generalized second law of gravitational thermodynamics is valid and the positivity of the temperature of the phantom fluid remains intact.

  7. Is the evidence for dark energy secure?

    E-Print Network [OSTI]

    Subir Sarkar

    2007-12-05

    Several kinds of astronomical observations, interpreted in the framework of the standard Friedmann-Robertson-Walker cosmology, have indicated that our universe is dominated by a Cosmological Constant. The dimming of distant Type Ia supernovae suggests that the expansion rate is accelerating, as if driven by vacuum energy, and this has been indirectly substantiated through studies of angular anisotropies in the cosmic microwave background (CMB) and of spatial correlations in the large-scale structure (LSS) of galaxies. However there is no compelling direct evidence yet for (the dynamical effects of) dark energy. The precision CMB data can be equally well fitted without dark energy if the spectrum of primordial density fluctuations is not quite scale-free and if the Hubble constant is lower globally than its locally measured value. The LSS data can also be satisfactorily fitted if there is a small component of hot dark matter, as would be provided by neutrinos of mass 0.5 eV. Although such an Einstein-de Sitter model cannot explain the SNe Ia Hubble diagram or the position of the `baryon acoustic oscillation' peak in the autocorrelation function of galaxies, it may be possible to do so e.g. in an inhomogeneous Lemaitre-Tolman-Bondi cosmology where we are located in a void which is expanding faster than the average. Such alternatives may seem contrived but this must be weighed against our lack of any fundamental understanding of the inferred tiny energy scale of the dark energy. It may well be an artifact of an oversimplified cosmological model, rather than having physical reality.

  8. Cosmology with Coupled Gravity and Dark Energy

    E-Print Network [OSTI]

    Ti-Pei Li

    2015-01-13

    Dark energy is a fundamental constituent of our universe, its status in the cosmological field equation should be equivalent to that of gravity. Here we construct a dark energy and matter gravity coupling (DEMC) model of cosmology in a way that dark energy and gravity are introduced into the cosmological field equation in parallel with each other from the beginning. The DEMC universe possesses a composite symmetry from global Galileo invariance and local Lorentz invariance. The observed evolution of the universe expansion rate at redshift z>1 is in tension with the standard LCDM model, but can be well predicted by the DEMC model from measurements of only nearby epochs. The so far most precise measured expansion rate at high z is quite a bit slower than the expectations from LCDM, but remarkably consistent with that from DEMC. It is hoped that the DEMC scenario can also help to solve other existing challenges to cosmology: large scale anomalies in CMB maps and large structures up to about 10^3 Mpc of a quasar group. The DEMC universe is a well defined mechanical system. From measurements we can quantitatively evaluate its total rest energy, present absolute radius and expanding speed.

  9. Dynamical system analysis for DBI dark energy interacting with dark matter

    E-Print Network [OSTI]

    Nilanjana Mahata; Subenoy Chakraborty

    2015-01-19

    A dynamical system analysis related to Dirac Born Infeld (DBI) cosmological model has been investigated in this present work. For spatially flat FRW space time, the Einstein field equation for DBI scenario has been used to study the dynamics of DBI dark energy interacting with dark matter. The DBI dark energy model is considered as a scalar field with a nonstandard kinetic energy term. An interaction between the DBI dark energy and dark matter is considered through a phenomenological interaction between DBI scalar field and the dark matter fluid. The field equations are reduced to an autonomous dynamical system by a suitable redefinition of the basic variables. The potential of the DBI scalar field is assumed to be exponential. Finally, critical points are determined, their nature have been analyzed and corresponding cosmological scenario has been discussed.

  10. Atom-interferometry constraints on dark energy

    E-Print Network [OSTI]

    Hamilton, Paul; Haslinger, Philipp; Simmons, Quinn; Müller, Holger; Khoury, Justin

    2015-01-01

    If dark energy---which drives the accelerated expansion of the universe---consists of a new light scalar field, it might be detectable as a "fifth force" between normal-matter objects, in potential conflict with precision tests of gravity. There has, however, been much theoretical progress in developing theories with screening mechanisms, which can evade detection by suppressing forces in regions of high density, such as the laboratory. One prominent example is the chameleon field. We reduce the effect of this screening mechanism by probing the chameleon with individual atoms rather than bulk matter. Using a cesium matter-wave interferometer near a spherical mass in an ultra-high vacuum chamber, we constrain a wide class of dynamical dark energy theories. Our experiment excludes a range of chameleon theories that reproduce the observed cosmic acceleration.

  11. Atom-interferometry constraints on dark energy

    E-Print Network [OSTI]

    Paul Hamilton; Matt Jaffe; Philipp Haslinger; Quinn Simmons; Holger Müller; Justin Khoury

    2015-07-02

    If dark energy --- which drives the accelerated expansion of the universe --- consists of a light scalar field, it might be detectable as a "fifth force" between normal-matter objects, in potential conflict with precision tests of gravity. Chameleon fields and other theories with screening mechanisms, however, can evade these tests by suppressing the forces in regions of high density, such as the laboratory. Using a cesium matter-wave interferometer near a spherical mass in an ultra-high vacuum chamber, we reduce the screening mechanism by probing the field with individual atoms rather than bulk matter. Thus, we constrain a wide class of dark energy theories, including a range of chameleon and other theories that reproduce the observed cosmic acceleration.

  12. Simple implementation of general dark energy models

    SciTech Connect (OSTI)

    Bloomfield, Jolyon K. [MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave #37241, Cambridge, MA, 02139 (United States); Pearson, Jonathan A., E-mail: jolyon@mit.edu, E-mail: jonathan.pearson@durham.ac.uk [Centre for Particle Theory, Department of Mathematical Sciences, Durham University, South Road, Durham, DH1 3LE (United Kingdom)

    2014-03-01

    We present a formalism for the numerical implementation of general theories of dark energy, combining the computational simplicity of the equation of state for perturbations approach with the generality of the effective field theory approach. An effective fluid description is employed, based on a general action describing single-scalar field models. The formalism is developed from first principles, and constructed keeping the goal of a simple implementation into CAMB in mind. Benefits of this approach include its straightforward implementation, the generality of the underlying theory, the fact that the evolved variables are physical quantities, and that model-independent phenomenological descriptions may be straightforwardly investigated. We hope this formulation will provide a powerful tool for the comparison of theoretical models of dark energy with observational data.

  13. Gauss Bonnet dark energy Chaplygin Gas Model

    E-Print Network [OSTI]

    Elahe Karimkhani; Asma Alaii; Abdolhossein Khodam-Mohammadi

    2015-02-27

    In this work we incorporate GB dark energy density and its modification, MGB, with Chaplygin gas component. We show that, presence of Chaplygin gas provides us a feature to obtain an exact solution for scalar field and potential of scalar field. Investigation on squared of sound speed provides a lower limit for constant parameters of MGB model. Also, we could find some bounds for free parameters of model.

  14. Electromagnetic Dark Energy and Gravitoelectrodynamics of Superconductors

    E-Print Network [OSTI]

    Clovis Jacinto de Matos

    2007-10-29

    It is shown that Beck and Mackey electromagnetic model of dark energy in superconductors can account for the non-classical inertial properties of superconductors, which have been conjectured by the author to explain the Cooper pair's mass excess reported by Cabrera and Tate. A new Einstein-Planck regime for gravitation in condensed matter is proposed as a natural scale to host the gravitoelectrodynamic properties of superconductors.

  15. An inhomogeneous alternative to dark energy?

    E-Print Network [OSTI]

    Alnes, H; Grøn, Ø; Alnes, Havard; Amarzguioui, Morad; Gron, Oyvind

    2006-01-01

    Recently, there have been suggestions that the apparent accelerated expansion of the universe is not caused by repulsive gravitation due to dark energy, but is rather a result of inhomogeneities in the distribution of matter. In this work, we investigate the behaviour of a dust dominated inhomogeneous Lemaitre-Tolman-Bondi universe model, and confront it with various astrophysical observations. We find that such a model can easily explain the observed luminosity distance-redshift relation of supernovae without the need for dark energy, when the inhomogeneity is in the form of an underdense bubble centered near the observer. With the additional assumption that the universe outside the bubble is approximately described by a homogeneous Einstein-de Sitter model, we find that the position of the first CMB peak can be made to match the WMAP observations. Whether or not it is possible to reproduce the entire CMB angular power spectrum in an inhomogeneous model without dark energy, is still an open question.

  16. An inhomogeneous alternative to dark energy?

    E-Print Network [OSTI]

    Havard Alnes; Morad Amarzguioui; Oyvind Gron

    2006-04-18

    Recently, there have been suggestions that the apparent accelerated expansion of the universe is not caused by repulsive gravitation due to dark energy, but is rather a result of inhomogeneities in the distribution of matter. In this work, we investigate the behaviour of a dust dominated inhomogeneous Lemaitre-Tolman-Bondi universe model, and confront it with various astrophysical observations. We find that such a model can easily explain the observed luminosity distance-redshift relation of supernovae without the need for dark energy, when the inhomogeneity is in the form of an underdense bubble centered near the observer. With the additional assumption that the universe outside the bubble is approximately described by a homogeneous Einstein-de Sitter model, we find that the position of the first CMB peak can be made to match the WMAP observations. Whether or not it is possible to reproduce the entire CMB angular power spectrum in an inhomogeneous model without dark energy, is still an open question.

  17. Non-adiabatic perturbations in Ricci dark energy model

    SciTech Connect (OSTI)

    Karwan, Khamphee; Thitapura, Thiti E-mail: nanodsci2523@hotmail.com

    2012-01-01

    We show that the non-adiabatic perturbations between Ricci dark energy and matter can grow both on superhorizon and subhorizon scales, and these non-adiabatic perturbations on subhorizon scales can lead to instability in this dark energy model. The rapidly growing non-adiabatic modes on subhorizon scales always occur when the equation of state parameter of dark energy starts to drop towards -1 near the end of matter era, except that the parameter ? of Ricci dark energy equals to 1/2. In the case where ? = 1/2, the rapidly growing non-adiabatic modes disappear when the perturbations in dark energy and matter are adiabatic initially. However, an adiabaticity between dark energy and matter perturbations at early time implies a non-adiabaticity between matter and radiation, this can influence the ordinary Sachs-Wolfe (OSW) effect. Since the amount of Ricci dark energy is not small during matter domination, the integrated Sachs-Wolfe (ISW) effect is greatly modified by density perturbations of dark energy, leading to a wrong shape of CMB power spectrum. The instability in Ricci dark energy is difficult to be alleviated if the effects of coupling between baryon and photon on dark energy perturbations are included.

  18. The Localized Energy Distribution of Dark Energy Star Solutions

    E-Print Network [OSTI]

    Paul Halpern; Michael Pecorino

    2013-03-05

    We examine the question of energy localization for an exact solution of Einstein's equations with a scalar field corresponding to the phantom energy interpretation of dark energy. We apply three different energy-momentum complexes, the Einstein, Papapetrou and M{\\o}ller prescriptions, to the exterior metric and determine the energy distribution for each. Comparing the results, we find that the three prescriptions yield identical energy distributions.

  19. Reissner-Nordstrom black hole in dark energy background

    E-Print Network [OSTI]

    Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh

    2014-11-29

    In this paper we propose a stationary solution of Einstein's field equations describing Reissner-Nordstrom black hole in dark energy background. It is to be regarded as the Reissner-Nordstrom black hole is embedded into the dark energy solution producing Reissner-Nordstrom-dark energy black hole. We find that the space-time geometry of Reissner-Nordstrom-dark energy solution is Petrov type $D$ in the classification of space-times. It is also shown that the embedded space-time possesses an energy-momentum tensor of the electromagnetic field interacting with the dark energy having negative pressure. We find the energy-momentum tensor for dark energy violates the the strong energy condition due to the negative pressure, whereas that of the electromagnetic field obeys the strong energy condition. It is shown that the time-like vector field for an observer in the Reissner-Nordstrom-dark energy space is expanding, accelerating, shearing and non-rotating. We investigate the surface gravity of the horizons for the embedded dark energy black hole. The characteristic properties of relativistic dark energy based on the de Sitter solution is discussed in an appendix.

  20. Structure formation in inhomogeneous Early Dark Energy models

    SciTech Connect (OSTI)

    Batista, R.C. [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, Caixa Postal 1524, 59072-970, Natal, Rio Grande do Norte (Brazil); Pace, F., E-mail: rbatista@ect.ufrn.br, E-mail: francesco.pace@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom)

    2013-06-01

    We study the impact of Early Dark Energy fluctuations in the linear and non-linear regimes of structure formation. In these models the energy density of dark energy is non-negligible at high redshifts and the fluctuations in the dark energy component can have the same order of magnitude of dark matter fluctuations. Since two basic approximations usually taken in the standard scenario of quintessence models, that both dark energy density during the matter dominated period and dark energy fluctuations on small scales are negligible, are not valid in such models, we first study approximate analytical solutions for dark matter and dark energy perturbations in the linear regime. This study is helpful to find consistent initial conditions for the system of equations and to analytically understand the effects of Early Dark Energy and its fluctuations, which are also verified numerically. In the linear regime we compute the matter growth and variation of the gravitational potential associated with the Integrated Sachs-Wolf effect, showing that these observables present important modifications due to Early Dark Energy fluctuations, though making them more similar to the ?CDM model. We also make use of the Spherical Collapse model to study the influence of Early Dark Energy fluctuations in the nonlinear regime of structure formation, especially on ?{sub c} parameter, and their contribution to the halo mass, which we show can be of the order of 10%. We finally compute how the number density of halos is modified in comparison to the ?CDM model and address the problem of how to correct the mass function in order to take into account the contribution of clustered dark energy. We conclude that the inhomogeneous Early Dark Energy models are more similar to the ?CDM model than its homogeneous counterparts.

  1. DarkStar VI | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTIONRobertsdale, Alabama (UtilityInstruments Inc JumpIowa: EnergyDark River, Minnesota: Energy

  2. Interacting vacuum energy in the dark sector

    SciTech Connect (OSTI)

    Chimento, L. P.; Carneiro, S.

    2015-03-26

    We analyse three cosmological scenarios with interaction in the dark sector, which are particular cases of a general expression for the energy flux from vacuum to matter. In the first case the interaction leads to a transition from an unstable de Sitter phase to a radiation dominated universe, avoiding in this way the initial singularity. In the second case the interaction gives rise to a slow-roll power-law inflation. Finally, the third scenario is a concordance model for the late-time universe, with the vacuum term decaying into cold dark matter. We identify the physics behind these forms of interaction and show that they can be described as particular types of the modified Chaplygin gas.

  3. The growth of structure in interacting dark energy models

    SciTech Connect (OSTI)

    Caldera-Cabral, Gabriela; Maartens, Roy; Schaefer, Bjoern Malte E-mail: roy.maartens@port.ac.uk

    2009-07-01

    If dark energy interacts with dark matter, there is a change in the background evolution of the universe, since the dark matter density no longer evolves as a{sup ?3}. In addition, the non-gravitational interaction affects the growth of structure. In principle, these changes allow us to detect and constrain an interaction in the dark sector. Here we investigate the growth factor and the weak lensing signal for a new class of interacting dark energy models. In these models, the interaction generalises the simple cases where one dark fluid decays into the other. In order to calculate the effect on structure formation, we perform a careful analysis of the perturbed interaction and its effect on peculiar velocities. Assuming a normalization to today's values of dark matter density and overdensity, the signal of the interaction is an enhancement (suppression) of both the growth factor and the lensing power, when the energy transfer in the background is from dark matter to dark energy (dark energy to dark matter)

  4. Constraining the Evolution of Dark Energy with a Combination of Galaxy Cluster Observables

    E-Print Network [OSTI]

    Sheng Wang; Justin Khoury; Zoltan Haiman; Morgan May

    2005-01-13

    We show that the abundance and redshift distribution ($dN/dz$) of galaxy clusters in future high--yield cluster surveys, combined with the spatial power spectrum ($P_c(k)$) of the same clusters, can place significant constraints on the evolution of the dark energy equation of state, $w=w(a)$. We evaluate the expected errors on $w_a=-dw/da$ and other cosmological parameters using a Fisher matrix approach, and simultaneously including cluster structure evolution parameters in our analysis. We study three different types of forthcoming surveys that will identify clusters based on their X-ray emission (such as DUO, the Dark Universe Observatory), their Sunyaev--Zel'dovich (SZ) decrement (such as SPT, the South Pole Telescope), or their weak lensing (WL) shear (such as LSST, the Large Synoptic Survey Telescope). We find that combining the cluster abundance and power spectrum significantly enhances constraints from either method alone. We show that the weak-lensing survey can deliver a constraint as tight as $\\Delta w_a \\sim 0.1$ on the evolution of the dark energy equation of state, and that the X-ray and SZ surveys each yield $\\Delta w_a \\sim 0.4$ separately, or $\\Delta w_a \\sim 0.2$ when these two surveys are combined. For the X-ray and SZ surveys, constraints on dark energy parameters are improved by a factor of two by combining the cluster data with cosmic microwave background (CMB) anisotropy measurements by Planck, but degrade by a factor of two if the survey is required to solve simultaneously for cosmological and cluster structure evolution parameters. The constraint on $w_a$ from the weak lensing survey is improved by $\\sim 25$% with the addition of Planck data.

  5. Constraining Dark Matter and Dark Energy Models using Astrophysical Surveys

    E-Print Network [OSTI]

    Cieplak, Agnieszka M.

    obser- vations of gamma-ray bursts (see Barnacka et al. (analysis of the Fermi Gamma-ray Burst Monitor data), whilefrom lensing of Gamma Ray Bursts, might therefore have to

  6. Discovering the Nature of Dark Energy: Towards Better Distances...

    Office of Scientific and Technical Information (OSTI)

    Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae -- Final Technical Report Filippenko, Alexei Vladimir Univ. California, Berkeley 79...

  7. Final Technical Report: Discovering the Nature of Dark Energy...

    Office of Scientific and Technical Information (OSTI)

    Report: Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae Citation Details In-Document Search Title: Final Technical Report: Discovering the...

  8. Nonparametric reconstruction of the dark energy equation of state...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Nonparametric reconstruction of the dark energy equation of state from diverse data sets Citation Details In-Document Search Title: Nonparametric reconstruction of...

  9. Optimizing New Dark Energy Experiments - Final Scientific Report

    SciTech Connect (OSTI)

    Jeffrey A. Newman

    2012-06-08

    This is the final scientific report for the University of Pittsburgh portion of the collaborative grant, 'Optimizing New Dark Energy Experiments'

  10. Impacts of dark energy on weighing neutrinos after Planck 2015

    E-Print Network [OSTI]

    Zhang, Xin

    2015-01-01

    We investigate how dark energy properties impact the cosmological limits on the total mass of active neutrinos. We consider two typical, simple dark energy models (that have only one more additional parameter than $\\Lambda$CDM), i.e., the $w$CDM model and the holographic dark energy (HDE) model, as examples, to make an analysis. In the cosmological fits, we use the Planck 2015 temperature and polarization data, in combination with other low-redshift observations, including the baryon acoustic oscillations, type Ia supernovae, and Hubble constant measurement, as well as the Planck lensing measurements. We find that, once dynamical dark energy is considered, the degeneracy between $\\sum m_\

  11. An Alternative Approach to Holographic Dark Energy

    E-Print Network [OSTI]

    Fergus Simpson

    2007-03-27

    Here we consider a scenario in which dark energy is associated with the apparent area of a surface in the early universe. In order to resemble the cosmological constant at late times, this hypothetical reference scale should maintain an approximately constant physical size during an asymptotically de-Sitter expansion. This is found to arise when the particle horizon - anticipated to be significantly greater than the Hubble length - is approaching the antipode of a closed universe. Depending on the constant of proportionality, either the ensuing inflationary period prevents the particle horizon from vanishing, or it may lead to a sequence of "Big Rips".

  12. Neutron Interferometry constrains dark energy chameleon fields

    E-Print Network [OSTI]

    H. Lemmel; Ph. Brax; A. N. Ivanov; T. Jenke; G. Pignol; M. Pitschmann; T. Potocar; M. Wellenzohn; M. Zawisky; H. Abele

    2015-02-20

    We present phase shift measurements for neutron matter waves in vacuum and in low pressure Helium using a method originally developed for neutron scattering length measurements in neutron interferometry. We search for phase shifts associated with a coupling to scalar fields. We set stringent limits for a scalar chameleon field, a prominent quintessence dark energy candidate. We find that the coupling constant $\\beta$ is less than 1.9 $\\times10^7$~for $n=1$ at 95\\% confidence level, where $n$ is an input parameter of the self--interaction of the chameleon field $\\varphi$ inversely proportional to $\\varphi^n$.

  13. Evidence for Dark Energy | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation Current HABFES OctoberEvan Racah Evan Racah 1517546Has Evidence of Dark Energy

  14. The prospects for constraining dark energy with future X-ray cluster gas mass fraction measurements

    E-Print Network [OSTI]

    David Rapetti; Steven W. Allen; Adam Mantz

    2008-06-25

    We examine the ability of a future X-ray observatory to constrain dark energy via measurements of the cluster X-ray gas mass fraction, fgas. We find that fgas measurements for a sample of ~500 hot, X-ray bright, dynamically relaxed clusters, to a precision of ~5 per cent, can be used to constrain dark energy with a Dark Energy Task Force (DETF) figure of merit of 15-40, with the possibility of boosting these values by 40 per cent or more by optimizing the redshift distribution of target clusters. Such constraints are comparable to those predicted by the DETF for other leading, planned dark energy experiments. A future fgas experiment will be preceded by a large X-ray or SZ survey that will find hot, X-ray luminous clusters out to high redshifts. Short `snapshot' observations with the new X-ray observatory should then be able to identify a sample of ~500 suitably relaxed systems. The redshift, temperature and X-ray luminosity range of interest has already been partially probed by existing X-ray cluster surveys which allow reasonable estimates of the fraction of clusters that will be suitably relaxed for fgas work. Our analysis uses a Markov Chain Monte Carlo method which fully captures the relevant degeneracies between parameters and facilitates the incorporation of priors and systematic uncertainties in the analysis. We explore the effects of such uncertainties for scenarios ranging from optimistic to pessimistic. We conclude that the fgas experiment will provide tight constraints on the mean matter and dark energy densities, with a peak sensitivity for dark energy work at redshifts midway between those of supernovae and baryon acoustic oscillation/weak lensing/cluster number counts experiments. In combination, these experiments should enable a precise measurement of the evolution of dark energy. (Abridged)

  15. Darke County, Ohio: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTIONRobertsdale, Alabama (UtilityInstruments Inc JumpIowa: EnergyDark River, Minnesota: EnergyDarke

  16. Could Dark Matter Interactions be an Alternative to Dark Energy ?

    E-Print Network [OSTI]

    S. Basilakos; M. Plionis

    2009-08-05

    We study the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Assuming that the dark matter obeys the collisional Boltzmann equation, we can derive analytical solutions of the global density evolution, which can accommodate an accelerated expansion, equivalent to either the {\\em quintessence} or the standard $\\Lambda$ models, with the present time located after the inflection point. This is possible if there is a disequilibrium between the DM particle creation and annihilation processes with the former process dominating, which creates an effective source term with negative pressure. Comparing the predicted Hubble expansion of one of the IDM models (the simplest) with observational data we find that the effective annihilation term is quite small, as suggested by a variety of other recent experiments.

  17. Interacting Dark Matter as an Alternative to Dark Energy

    E-Print Network [OSTI]

    Spyros Basilakos; Manolis Plionis

    2009-11-12

    We investigate the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Considering that the dark matter obeys the collisional Boltzmann equation, we can obtain analytical solutions of the global density evolution, which can accommodate an accelerated expansion, equivalent to either the {\\em quintessence} or the standard $\\Lambda$ models. This is possible if there is a disequilibrium between the DM particle creation and annihilation processes with the former process dominating, which creates an effective source term with negative pressure. Comparing the predicted Hubble expansion of one of the IDM models (the simplest) with observational data, we find that the effective annihilation term is quite small, as suggested by various experiments.

  18. Interacting Dark Matter as an Alternative to Dark Energy

    E-Print Network [OSTI]

    Basilakos, Spyros

    2009-01-01

    We investigate the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Considering that the dark matter obeys the collisional Boltzmann equation, we can obtain analytical solutions of the global density evolution, which can accommodate an accelerated expansion, equivalent to either the {\\em quintessence} or the standard $\\Lambda$ models. This is possible if there is a disequilibrium between the DM particle creation and annihilation processes with the former process dominating, which creates an effective source term with negative pressure. Comparing the predicted Hubble expansion of one of the IDM models (the simplest) with observational data, we find that the effective annihilation term is quite small, as suggested by various experiments.

  19. The effective field theory of dark energy

    SciTech Connect (OSTI)

    Gubitosi, Giulia; Vernizzi, Filippo; Piazza, Federico E-mail: fpiazza@apc.univ-paris7.fr

    2013-02-01

    We propose a universal description of dark energy and modified gravity that includes all single-field models. By extending a formalism previously applied to inflation, we consider the metric universally coupled to matter fields and we write in terms of it the most general unitary gauge action consistent with the residual unbroken symmetries of spatial diffeomorphisms. Our action is particularly suited for cosmological perturbation theory: the background evolution depends on only three operators. All other operators start at least at quadratic order in the perturbations and their effects can be studied independently and systematically. In particular, we focus on the properties of a few operators which appear in non-minimally coupled scalar-tensor gravity and galileon theories. In this context, we study the mixing between gravity and the scalar degree of freedom. We assess the quantum and classical stability, derive the speed of sound of fluctuations and the renormalization of the Newton constant. The scalar can always be de-mixed from gravity at quadratic order in the perturbations, but not necessarily through a conformal rescaling of the metric. We show how to express covariant field-operators in our formalism and give several explicit examples of dark energy and modified gravity models in our language. Finally, we discuss the relation with the covariant EFT methods recently appeared in the literature.

  20. Cosmological electromagnetic fields and dark energy

    E-Print Network [OSTI]

    Jose Beltran Jimenez; Antonio L. Maroto

    2009-02-18

    We show that the presence of a temporal electromagnetic field on cosmological scales generates an effective cosmological constant which can account for the accelerated expansion of the universe. Primordial electromagnetic quantum fluctuations produced during electroweak scale inflation could naturally explain the presence of this field and also the measured value of the dark energy density. The behavior of the electromagnetic field on cosmological scales is found to differ from the well studied short-distance behavior and, in fact, the presence of a non-vanishing cosmological constant could be signalling the breakdown of gauge invariance on cosmological scales. The theory is compatible with all the local gravity tests, and is free from classical or quantum instabilities. Thus we see that, not only the true nature of dark energy can be established without resorting to new physics, but also the value of the cosmological constant finds a natural explanation in the context of standard inflationary cosmology. This mechanism could be discriminated from a true cosmological constant by upcoming observations of CMB anisotropies and large scale structure.

  1. The dynamics of universe for exponential decaying dark energy

    E-Print Network [OSTI]

    Bostan, Nilay

    2015-01-01

    In this study we consider an exponential decaying form for dark energy as EoS parameter in order to discuss the dynamics of the universe. Firstly, assuming that universe is filled with an ideal fluid which consists of exponential decaying dark energy we obtain time dependent behavior of several physical quantities such as energy density, pressure and others for dark energy, dark energy-matter coupling and non-coupling cases. Secondly, using scalar field instead of an ideal fluid we obtain these physical quantities in terms of scalar potential and kinetic term for the same cases in scalar-tensor formalism. Finally we show that ideal fluid and scalar-tensor description of dark energy give mathematically equivalent results for this EoS parameter.

  2. The dynamics of universe for exponential decaying dark energy

    E-Print Network [OSTI]

    Nilay Bostan; Ekrem Aydiner

    2015-08-12

    In this study we consider an exponential decaying form for dark energy as EoS parameter in order to discuss the dynamics of the universe. Firstly, assuming that universe is filled with an ideal fluid which consists of exponential decaying dark energy we obtain time dependent behavior of several physical quantities such as energy density, pressure and others for dark energy, dark energy-matter coupling and non-coupling cases. Secondly, using scalar field instead of an ideal fluid we obtain these physical quantities in terms of scalar potential and kinetic term for the same cases in scalar-tensor formalism. Finally we show that ideal fluid and scalar-tensor description of dark energy give mathematically equivalent results for this EoS parameter.

  3. Dynamical Systems Analysis of Various Dark Energy Models

    E-Print Network [OSTI]

    Nandan Roy

    2015-11-25

    In this thesis, we used dynamical systems analysis to find the qualitative behaviour of some dark energy models. Specifically, dynamical systems analysis of quintessence scalar field models, chameleon scalar field models and holographic models of dark energy are discussed in this thesis.

  4. Evolution of the horizons for dark energy universe

    E-Print Network [OSTI]

    Ritabrata Biswas; Nairwita Mazumder; Subenoy Chakraborty

    2011-06-12

    Recent observational evidences of accelerating phase of the universe strongly demand that the dominating matter in the universe is in the form of dark energy. In this work, we study the evolution of the apparent and event horizons for various dark energy models and examine their behavior across phantom barrier line.

  5. Dynamical Systems Analysis of Various Dark Energy Models

    E-Print Network [OSTI]

    Roy, Nandan

    2015-01-01

    In this thesis, we used dynamical systems analysis to find the qualitative behaviour of some dark energy models. Specifically, dynamical systems analysis of quintessence scalar field models, chameleon scalar field models and holographic models of dark energy are discussed in this thesis.

  6. The QCD nature of Dark Energy

    E-Print Network [OSTI]

    Federico R. Urban; Ariel R. Zhitnitsky

    2010-03-12

    The origin of the observed dark energy could be explained entirely within the standard model, with no new fields required. We show how the low-energy sector of the chiral QCD Lagrangian, once embedded in a non-trivial spacetime, gives rise to a cosmological vacuum energy density which can be can be presented entirely in terms of QCD parameters and the Hubble constant $H$ as $\\rho_\\Lambda \\simeq H \\cdot m_q\\la\\bar{q}q\\ra /m_{\\eta'} \\sim (4.3\\cdot 10^{-3} \\text{eV})^4$. In this work we focus on the dynamics of the ghost fields that are essential ingredients of the aforementioned Lagrangian. In particular, we argue that the Veneziano ghost, being unphysical in the usual Minkowski QFT, becomes a physical degree of freedom if the universe is expanding. As an immediate consequence, all relevant effects are naturally very small as they are proportional to the rate of expansion $H/ \\Lqcd \\sim 10^{-41}$. The co-existence of these two drastically different scales ($\\Lqcd \\sim 100 $ MeV and $H \\sim 10^{-33}$ eV) is a direct consequence of the auxiliary conditions on the physical Hilbert space that are necessary to keep the theory unitary. The exact cancellation taking place in Minkowski space due to this auxiliary condition is slightly violated when the system is upgraded to an expanding background. Nevertheless, this "tiny" effect is in fact the driving force accelerating the universe today. We also derive the time dependent equation of state $w(t)$ for the dark energy component which tracks the dynamics of the Veneziano ghost in a FLRW universe. Finally, we comment on how the same physical phenomena can be recovered in Witten's approach to the U(1) problem when the ghost degree of freedom is not even present in the system.

  7. Dark Matter and Dark Energy from the solution of the strong CP problem

    E-Print Network [OSTI]

    Roberto Mainini; Silvio A. Bonometto

    2004-07-19

    The Peccei Quinn (PQ) solution of the strong CP problem requires the existence of axions, which are a viable candidate for Dark Matter. Here we show that, if the Nambu Goldstone potential of the PQ model is replaced by a potential V(|\\Phi|) admitting a tracker solution, the scalar field |\\Phi| can account for Dark Energy, while the phase of \\Phi yields axion Dark Matter. Such Dark Matter and Dark Energy turn out to be weakly coupled. If V is a SUGRA potential, the model essentially depends on a single parameter, the energy scale \\Lambda. Once we set \\Lambda \\simeq 10^{10} GeV, at the quark--hadron transition, |\\Phi| naturally passes through values suitable to solve the strong CP problem, later growing to values providing fair amounts of Dark Matter and Dark Energy. In this model, the linear growth factor, from recombination to now, is quite close to \\LambdaCDM. The selected \\Lambda value can be an indication of the scale where the soft breaking of SUSY occurred.

  8. Site Energy Surveys 

    E-Print Network [OSTI]

    Lockett, W., Jr.; Guide, J. J.

    1981-01-01

    Operating improvements and selected investments have already improved US refining and petrochemical energy utilization efficiency by about 20%, compared to 1972 operating efficiencies. This is equivalent to saving well over 250,000 B/D of crude...

  9. Fermilab | Science | Particle Physics | Dark matter and dark energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory ofDid you not find whatGasEnergyfeature photo featureParticleDark matter and

  10. Large Scale Cosmic Microwave Background Anisotropies and Dark Energy

    E-Print Network [OSTI]

    J. Weller; A. M. Lewis

    2003-08-29

    In this note we investigate the effects of perturbations in a dark energy component with a constant equation of state on large scale cosmic microwave background anisotropies. The inclusion of perturbations increases the large scale power. We investigate more speculative dark energy models with w<-1 and find the opposite behaviour. Overall the inclusion of perturbations in the dark energy component increases the degeneracies. We generalise the parameterization of the dark energy fluctuations to allow for an arbitrary const ant sound speeds and show how constraints from cosmic microwave background experiments change if this is included. Combining cosmic microwave background with large scale structure, Hubble parameter and Supernovae observations we obtain w=-1.02+-0.16 (1 sigma) as a constraint on the equation of state, which is almost independent of the sound speed chosen. With the presented analysis we find no significant constraint on the constant speed of sound of the dark energy component.

  11. Validity of Thermodynamical Laws in Dark Energy Filled Universe

    E-Print Network [OSTI]

    Samarpita Bhattacharya; Ujjal Debnath

    2010-12-26

    We have considered the flat FRW model of the universe which is filled with only dark energy. The general descriptions of first and second laws of thermodynamics are investigated on the apparent horizon and event horizon of the universe. We have assumed the equation of state of three different types of dark energy models. We have examined the validity of first and second laws of thermodynamics on apparent and event horizons for these dark energies. For these dark energy models, it has been found that on the apparent horizon, first and second laws are always valid. On the event horizon, the laws are break down for dark energy models 1 and 2. For model 3, first law cannot be satisfied on the event horizon, but second law may be satisfied at the late stage of the evolution of the universe and so the validity of second law on the event horizon depends on the values of the parameters only.

  12. Discovery of Dark Energy Ushered in a New Era in Computational...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Discovery of Dark Energy Ushered in a New Era in Computational Cosmology Discovery of Dark Energy Ushered in a New Era in Computational Cosmology October 4, 2011 | Tags:...

  13. Transportation Energy Consumption Surveys

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home PageMonthly","10/2015"4,"Ames5 Tables July 1996 Energy Information Administration Office of Coal, Nuclear,DecadeYearbyWithdrawalsHome6,672(MillionFeet)Product:Energy

  14. Residential Energy Consumption Survey: Quality Profile

    SciTech Connect (OSTI)

    1996-03-01

    The Residential Energy Consumption Survey (RECS) is a periodic national survey that provides timely information about energy consumption and expenditures of U.S. households and about energy-related characteristics of housing units. The survey was first conducted in 1978 as the National Interim Energy Consumption Survey (NIECS), and the 1979 survey was called the Household Screener Survey. From 1980 through 1982 RECS was conducted annually. The next RECS was fielded in 1984, and since then, the survey has been undertaken at 3-year intervals. The most recent RECS was conducted in 1993.

  15. Dark energy as a massive vector field

    E-Print Network [OSTI]

    C. G. Boehmer; T. Harko

    2007-01-11

    We propose that the Universe is filled with a massive vector field, non-minimally coupled to gravitation. The field equations of the model are consistently derived and their application to cosmology is considered. The Friedmann equations acquire an extra dark-energy component, which is proportional to the mass of the vector particle. This leads to a late-time accelerated de Sitter type expansion. The free parameters of the model (gravitational coupling constants and initial value of the cosmological vector field) can be estimated by using the PPN solar system constraints. The mass of the cosmological massive vector particle, which may represent the main component of the Universe, is of the order of 10^-63 g.

  16. Cosmological degeneracy versus cosmography: a cosmographic dark energy model

    E-Print Network [OSTI]

    Orlando Luongo; Giovanni Battista Pisani; Antonio Troisi

    2015-12-22

    In this work we use cosmography to alleviate the degeneracy among cosmological models, proposing a way to parameterize matter and dark energy in terms of cosmokinematics quantities. The recipe of using cosmography allows to expand observable quantities in Taylor series and to directly compare those expansions with data. We adopt this strategy and we propose a fully self-consistent parametrization of the total energy density driving the late time universe speed up. Afterwards, we describe a feasible \\emph{cosmographic dark energy model}, in which matter is fixed whereas dark energy evolves by means of the cosmographic series. Our technique provides robust constraints on cosmokinematic parameters, permitting one to separately bound matter from dark energy densities. Our cosmographic dark energy model turns out to be one parameter only, but differently from the $\\Lambda$CDM paradigm, it does not contain ansatz on the dark energy form. In addition, we even determine the free parameter of our model in suitable $1\\sigma$ intervals through Monte Carlo analyses based on the Metropolis algorithm. We compare our results with the standard concordance model and we find that our treatment seems to indicate that dark energy slightly evolves in time, reducing to a pure cosmological constant only as $z\\rightarrow0$.

  17. Anisotropic Dark Energy and the Generalized Second Law of Thermodynamics

    E-Print Network [OSTI]

    M. Sharif; Farida Khanum

    2011-11-12

    We consider a Bianchi type $I$ model in which anisotropic dark energy is interacting with dark matter and anisotropic radiation. With this scenario, we investigate the validity of the generalized second law of thermodynamics. It is concluded that the validity of this law depends on different parameters like shear, skewness and equation of state.

  18. Structure formation in the presence of dark energy perturbations

    E-Print Network [OSTI]

    L. R. Abramo; R. C. Batista; L. Liberato; R. Rosenfeld

    2007-11-28

    We study non-linear structure formation in the presence of dark energy. The influence of dark energy on the growth of large-scale cosmological structures is exerted both through its background effect on the expansion rate, and through its perturbations as well. In order to compute the rate of formation of massive objects we employ the Spherical Collapse formalism, which we generalize to include fluids with pressure. We show that the resulting non-linear evolution equations are identical to the ones obtained in the Pseudo-Newtonian approach to cosmological perturbations, in the regime where an equation of state serves to describe both the background pressure relative to density, and the pressure perturbations relative to the density perturbations as well. We then consider a wide range of constant and time-dependent equations of state (including phantom models) parametrized in a standard way, and study their impact on the non-linear growth of structure. The main effect is the formation of dark energy structure associated with the dark matter halo: non-phantom equations of state induce the formation of a dark energy halo, damping the growth of structures; phantom models, on the other hand, generate dark energy voids, enhancing structure growth. Finally, we employ the Press-Schechter formalism to compute how dark energy affects the number of massive objects as a function of redshift.

  19. Dark Energy and Some Alternatives: a Brief Overview

    E-Print Network [OSTI]

    J. S. Alcaniz

    2006-08-29

    The high-quality cosmological data, which became available in the last decade, have thrusted upon us a rather preposterous composition for the universe which poses one of the greatest challenges theoretical physics has ever faced: the so-called dark energy. By focusing our attention on specific examples of dark energy scenarios, we discuss three different candidates for this dark component, namely, a decaying vacuum energy or time-varying cosmological constant [$\\Lambda(t)$], a rolling homogeneous quintessence field ($\\Phi$), and modifications in gravity due to extra spatial dimensions. As discussed, all these candidates [along with the vacuum energy or cosmological constant ($\\Lambda$)] seem somewhat to be able to explain the current observational results, which hampers any definitive conclusion on the actual nature of the dark energy.

  20. Dark Energy and Some Alternatives: a Brief Overview

    E-Print Network [OSTI]

    Alcaniz, J S

    2006-01-01

    The high-quality cosmological data, which became available in the last decade, have thrusted upon us a rather preposterous composition for the universe which poses one of the greatest challenges theoretical physics has ever faced: the so-called dark energy. By focusing our attention on specific examples of dark energy scenarios, we discuss three different candidates for this dark component, namely, a decaying vacuum energy or time-varying cosmological constant [$\\Lambda(t)$], a rolling homogeneous quintessence field ($\\Phi$), and modifications in gravity due to extra spatial dimensions. As discussed, all these candidates [along with the vacuum energy or cosmological constant ($\\Lambda$)] seem somewhat to be able to explain the current observational results, which hampers any definitive conclusion on the actual nature of the dark energy.

  1. Fermilab | Newsroom | Press Releases | August 17, 2015: Dark...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    2015 FOR IMMEDIATE RELEASE Dark Energy Survey finds more celestial neighbors New dwarf galaxy candidates could mean our sky is more crowded than we thought photo The Dark Energy...

  2. Spectroscopic Needs for Imaging Dark Energy Experiments

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Newman, Jeffrey A.; Slosar, Anze; Abate, Alexandra; Abdalla, Filipe B.; Allam, Sahar; Allen, Steven W.; Ansari, Reza; Bailey, Stephen; Barkhouse, Wayne A.; Beers, Timothy C.; et al

    2015-03-15

    Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments. Hence, to achieve their full potential, imaging-based experiments will require large setsmore »of objects with spectroscopically-determined redshifts, for two purposes: Training: Objects with known redshift are needed to map out the relationship between object color and z (or, equivalently, to determine empirically-calibrated templates describing the rest-frame spectra of the full range of galaxies, which may be used to predict the color-z relation). The ultimate goal of training is to minimize each moment of the distribution of differences between photometric redshift estimates and the true redshifts of objects, making the relationship between them as tight as possible. The larger and more complete our “training set” of spectroscopic redshifts is, the smaller the RMS photo-z errors should be, increasing the constraining power of imaging experiments; Requirements: Spectroscopic redshift measurements for ~30,000 objects over >~15 widely-separated regions, each at least ~20 arcmin in diameter, and reaching the faintest objects used in a given experiment, will likely be necessary if photometric redshifts are to be trained and calibrated with conventional techniques. Larger, more complete samples (i.e., with longer exposure times) can improve photo-z algorithms and reduce scatter further, enhancing the science return from planned experiments greatly (increasing the Dark Energy Task Force figure of merit by up to ~50%); Options: This spectroscopy will most efficiently be done by covering as much of the optical and near-infrared spectrum as possible at modestly high spectral resolution (?/?? > ~3000), while maximizing the telescope collecting area, field of view on the sky, and multiplexing of simultaneous spectra. The most efficient instrument for this would likely be either the proposed GMACS/MANIFEST spectrograph for the Giant Magellan Telescope or the OPTIMOS spectrograph for the European Extremely Large Telescope, depending on actual properties when built. The PFS spectrograph at Subaru would be next best and available considerably earlier, c. 2018; the proposed ngCFHT and SSST telescopes would have similar capabilities but start later. Other key options, in order of increasing total time required, are the WFOS spectrograph at TMT, MOONS at the VLT, and DESI at the Mayall 4 m telescope (or the similar 4MOST and WEAVE projects); of these, only DESI, MOONS, and PFS are expected to be available before 2020. Table 2-3 of this white paper summarizes the observation time required at each facility for strawman training samples. To attain secure redshift measurements for a high fraction of targeted objects and cover the full redshift span of future experiments, additional near-infrared spectroscopy will also be required; this is best done from space, particularly with WFIRST-2.4 and JWST; Calibration: The first several moments of redshift distributions (the mean, RMS redshift dispersion, etc.), must be known to high accuracy for cosmological constraints not to be systematics-dominated (equivalently, the moments of the distribution of differences between photometric and true redshifts could be determined instead). The ultimate goal of calibration is to characterize these moments for every subsample used in analyses - i.e., to minimize the uncertainty in their mean redshift, RMS dispersion, etc. – rather than to make the m

  3. Spectroscopic Needs for Imaging Dark Energy Experiments

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Newman, Jeffrey A. [Univ. of Pittsburgh and PITT PACC, PA (United States). Dept of Physics and Astronomy; Slosar, Anze [Brookhaven National Laboratory (BNL), Upton, NY (United States); Abate, Alexandra [Univ. of Arizona, Tucson, AZ (United States); Abdalla, Filipe B. [Univ. College London (United Kingdom); Allam, Sahar [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Allen, Steven W. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Ansari, Reza [LAL Univ. Paris-Sud, Orsay (France); Bailey, Stephen [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Barkhouse, Wayne A. [Univ. of North Dakota, Grand Forks, ND (United States); Beers, Timothy C. [National Optical Astronomy Observations, Tucson, AZ (United States); Blanton, Michael R. [New York Univ., NY (United States); Brodwin, Mark [Univ. of Missouri at Kansas City, Kansas City, MO (United States); Brownstein, Joel R. [Univ. of Utah, Salt Lake City, UT (United States); Brunner, Robert J. [Illinois Univ., Urbana, IL (United States); Carrasco-Kind, Matias [Illinois Univ., Urbana, IL (United States); Cervantes-Cota, Jorge [Inst. Nacional de Investigaciones Nucleares (ININ), Escandon (Mexico); Chisari, Nora Elisa [Princeton Univ., Princeton, NJ (United States); Colless, Matthew [Australian National Univ., Canberra (Australia). Research School of Astronomy and Astrophysics; Comparat, Johan [Campus of International Excellence UAM and CSIC, Madrid (Spain); Coupon, Jean [Univ. of Geneva (Switzerland). Astronomical Observatory; Cheu, Elliott [Univ. of Arizona, Tucson, AZ (United States); Cunha, Carlos E. [Stanford Univ., Stanford, CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; de la Macorra, Alex [UNAM, Mexico City (Mexico). Dept. de Fisica Teorica and Inst. Avanzado de Cosmologia; Dell’Antonio, Ian P. [Brown Univ., Providence, RI (United States); Frye, Brenda L. [Univ. of Arizona, Tucson, AZ (United States); Gawiser, Eric J. [State Univ. of New Jersey, Piscataway, NJ (United States); Gehrels, Neil [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Grady, Kevin [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Hagen, Alex [Penn State Univ., University Park, PA (United States); Hall, Patrick B. [York Univ., Toronto, ON (Canada); Hearin, Andrew P. [Yale Univ., New Haven, CT (United States); Hildebrandt, Hendrik [Argelander-Inst. fuer Astronomie, Bonn (Germany); Hirata, Christopher M. [Ohio State Univ., Columbus, OH (United States); Ho, Shirley [Carnegie Mellon Univ., Pittsburgh, PA (United States). McWilliams Center for Cosmology; Honscheid, Klaus [Ohio State Univ., Columbus, OH (United States); Huterer, Dragan [Univ. of Michigan, Ann Arbor, MI (United States); Ivezic, Zeljko [Univ. of Washington, Seattle, WA (United States); Kneib, Jean -Paul [Laboratoire d'Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL) (Swizerland); Laboratoire d'Astrophysique de Marseille (France); Kruk, Jeffrey W. [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Lahav, Ofer [Univ. College London, Bloomsbury (United Kingdom); Mandelbaum, Rachel [Carnegie Mellon Univ., Pittsburgh, PA (United States). McWilliams Center for Cosmology; Marshall, Jennifer L. [Texas A and M Univ., College Station, TX (United States); Matthews, Daniel J. [Univ. of Pittsburgh and PITT PACC, PA (United States). Dept of Physics and Astronomy; Menard, Brice [Johns Hopkins Univ., Baltimore, MD (United States); Miquel, Ramon [Univ. Autonoma de Barcelona (Spain). Inst. de Fisica d'Altes Energies (IFAE); Moniez, Marc [Univ. Paris-Sud, Orsay (France); Moos, H. W. [Johns Hopkins Univ., Baltimore, MD (United States); Moustakas, John [Siena College, Loudonville, NY (United States); Papovich, Casey [Texas A and M Univ., College Station, TX (United States); Peacock, John A. [Univ. of Edinburgh (United Kingdom). Inst. for Astronomy, Royal Observatory; Park, Changbom [Korea Inst. for Advanced Study, Seoul (Korea, Republic of); Rhodes, Jason [Jet Propulsion Lab./Caltech, Pasadena, CA (United States)

    2015-03-01

    Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments. Hence, to achieve their full potential, imaging-based experiments will require large sets of objects with spectroscopically-determined redshifts, for two purposes: Training: Objects with known redshift are needed to map out the relationship between object color and z (or, equivalently, to determine empirically-calibrated templates describing the rest-frame spectra of the full range of galaxies, which may be used to predict the color-z relation). The ultimate goal of training is to minimize each moment of the distribution of differences between photometric redshift estimates and the true redshifts of objects, making the relationship between them as tight as possible. The larger and more complete our “training set” of spectroscopic redshifts is, the smaller the RMS photo-z errors should be, increasing the constraining power of imaging experiments; Requirements: Spectroscopic redshift measurements for ~30,000 objects over >~15 widely-separated regions, each at least ~20 arcmin in diameter, and reaching the faintest objects used in a given experiment, will likely be necessary if photometric redshifts are to be trained and calibrated with conventional techniques. Larger, more complete samples (i.e., with longer exposure times) can improve photo-z algorithms and reduce scatter further, enhancing the science return from planned experiments greatly (increasing the Dark Energy Task Force figure of merit by up to ~50%); Options: This spectroscopy will most efficiently be done by covering as much of the optical and near-infrared spectrum as possible at modestly high spectral resolution (?/?? > ~3000), while maximizing the telescope collecting area, field of view on the sky, and multiplexing of simultaneous spectra. The most efficient instrument for this would likely be either the proposed GMACS/MANIFEST spectrograph for the Giant Magellan Telescope or the OPTIMOS spectrograph for the European Extremely Large Telescope, depending on actual properties when built. The PFS spectrograph at Subaru would be next best and available considerably earlier, c. 2018; the proposed ngCFHT and SSST telescopes would have similar capabilities but start later. Other key options, in order of increasing total time required, are the WFOS spectrograph at TMT, MOONS at the VLT, and DESI at the Mayall 4 m telescope (or the similar 4MOST and WEAVE projects); of these, only DESI, MOONS, and PFS are expected to be available before 2020. Table 2-3 of this white paper summarizes the observation time required at each facility for strawman training samples. To attain secure redshift measurements for a high fraction of targeted objects and cover the full redshift span of future experiments, additional near-infrared spectroscopy will also be required; this is best done from space, particularly with WFIRST-2.4 and JWST; Calibration: The first several moments of redshift distributions (the mean, RMS redshift dispersion, etc.), must be known to high accuracy for cosmological constraints not to be systematics-dominated (equivalently, the moments of the distribution of differences between photometric and true redshifts could be determined instead). The ultimate goal of calibration is to characterize these moments for every subsample used in analyses - i.e., to minimize the uncertainty in their mean redshift, RMS dispersion, etc. – rather than to make the moments themselve

  4. Planck constraints on holographic dark energy

    SciTech Connect (OSTI)

    Li, Miao; Zhang, Zhenhui [Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, Xiao-Dong [Korea Institute for Advanced Study, Hoegiro 87, Dongdaemun-Gu, Seoul 130-722 (Korea, Republic of); Ma, Yin-Zhe [Department of Physics and Astronomy, University of British Columbia, Vancouver, V6T 1Z1, BC Canada (Canada); Zhang, Xin, E-mail: mli@itp.ac.cn, E-mail: xiaodongli@kias.re.kr, E-mail: mayinzhe@phas.ubc.ca, E-mail: zhangxin@mail.neu.edu.cn, E-mail: zhangzhh@itp.ac.cn [College of Sciences, Northeastern University, Shenyang 110004 (China)

    2013-09-01

    We perform a detailed investigation on the cosmological constraints on the holographic dark energy (HDE) model by using the Plank data. We find that HDE can provide a good fit to the Plank high-l (l ?> 40) temperature power spectrum, while the discrepancy at l ? 20-40 found in the ?CDM model remains unsolved in the HDE model. The Plank data alone can lead to strong and reliable constraint on the HDE parameter c. At the 68% confidence level (CL), we obtain c = 0.508 ± 0.207 with Plank+WP+lensing, favoring the present phantom behavior of HDE at the more than 2? CL. By combining Plank+WP with the external astrophysical data sets, i.e. the BAO measurements from 6dFGS+SDSS DR7(R)+BOSS DR9, the direct Hubble constant measurement result (H{sub 0} = 73.8 ± 2.4 kms{sup ?1}Mpc{sup ?1}) from the HST, the SNLS3 supernovae data set, and Union2.1 supernovae data set, we get the 68% CL constraint results c = 0.484 ± 0.070, 0.474 ± 0.049, 0.594 ± 0.051, and 0.642 ± 0.066, respectively. The constraints can be improved by 2%-15% if we further add the Plank lensing data into the analysis. Compared with the WMAP-9 results, the Plank results reduce the error by 30%-60%, and prefer a phantom-like HDE at higher significant level. We also investigate the tension between different data sets. We find no evident tension when we combine Plank data with BAO and HST. Especially, we find that the strong correlation between ?{sub m}h{sup 3} and dark energy parameters is helpful in relieving the tension between the Plank and HST measurements. The residual value of ?{sup 2}{sub Plank+WP+HST}??{sup 2}{sub Plank+WP} is 7.8 in the ?CDM model, and is reduced to 1.0 or 0.3 if we switch the dark energy to w model or the holographic model. When we introduce supernovae data sets into the analysis, some tension appears. We find that the SNLS3 data set is in tension with all other data sets; for example, for the Plank+WP, WMAP-9 and BAO+HST, the corresponding ??{sup 2} is equal to 6.4, 3.5 and 4.1, respectively. As a comparison, the Union2.1 data set is consistent with these three data sets, but the combination Union2.1+BAO+HST is in tension with Plank+WP+lensing, corresponding to a large ??{sup 2} that is equal to 8.6 (1.4% probability). Thus, combining internal inconsistent data sets (SNIa+BAO+HST with Plank+WP+lensing) can lead to ambiguous results, and it is necessary to perform the HDE data analysis for each independent data sets. Our tightest self-consistent constraint is c = 0.495 ± 0.039 obtained from Plank+WP+BAO+HST+lensing.

  5. Spectroscopic Needs for Imaging Dark Energy Experiments

    SciTech Connect (OSTI)

    Newman, Jeffrey A.; Slosar, Anze; Abate, Alexandra; Abdalla, Filipe B.; Allam, Sahar; Allen, Steven W.; Ansari, Reza; Bailey, Stephen; Barkhouse, Wayne A.; Beers, Timothy C.; Blanton, Michael R.; Brodwin, Mark; Brownstein, Joel R.; Brunner, Robert J.; Carrasco-Kind, Matias; Cervantes-Cota, Jorge; Chisari, Nora Elisa; Colless, Matthew; Comparat, Johan; Coupon, Jean; Cheu, Elliott; Cunha, Carlos E.; de la Macorra, Alex; Dell’Antonio, Ian P.; Frye, Brenda L.; Gawiser, Eric J.; Gehrels, Neil; Grady, Kevin; Hagen, Alex; Hall, Patrick B.; Hearin, Andrew P.; Hildebrandt, Hendrik; Hirata, Christopher M.; Ho, Shirley; Honscheid, Klaus; Huterer, Dragan; Ivezic, Zeljko; Kneib, Jean -Paul; Kruk, Jeffrey W.; Lahav, Ofer; Mandelbaum, Rachel; Marshall, Jennifer L.; Matthews, Daniel J.; Menard, Brice; Miquel, Ramon; Moniez, Marc; Moos, H. W.; Moustakas, John; Papovich, Casey; Peacock, John A.; Park, Changbom; Rhodes, Jason; Sadeh, Iftach; Schmidt, Samuel J.; Stern, Daniel K.; Tyson, J. Anthony; von der Linden, Anja; Wechsler, Risa H.; Wood-Vasey, W. M.; Zentner, A.

    2015-03-15

    Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments. Hence, to achieve their full potential, imaging-based experiments will require large sets of objects with spectroscopically-determined redshifts, for two purposes: Training: Objects with known redshift are needed to map out the relationship between object color and z (or, equivalently, to determine empirically-calibrated templates describing the rest-frame spectra of the full range of galaxies, which may be used to predict the color-z relation). The ultimate goal of training is to minimize each moment of the distribution of differences between photometric redshift estimates and the true redshifts of objects, making the relationship between them as tight as possible. The larger and more complete our “training set” of spectroscopic redshifts is, the smaller the RMS photo-z errors should be, increasing the constraining power of imaging experiments; Requirements: Spectroscopic redshift measurements for ~30,000 objects over >~15 widely-separated regions, each at least ~20 arcmin in diameter, and reaching the faintest objects used in a given experiment, will likely be necessary if photometric redshifts are to be trained and calibrated with conventional techniques. Larger, more complete samples (i.e., with longer exposure times) can improve photo-z algorithms and reduce scatter further, enhancing the science return from planned experiments greatly (increasing the Dark Energy Task Force figure of merit by up to ~50%); Options: This spectroscopy will most efficiently be done by covering as much of the optical and near-infrared spectrum as possible at modestly high spectral resolution (?/?? > ~3000), while maximizing the telescope collecting area, field of view on the sky, and multiplexing of simultaneous spectra. The most efficient instrument for this would likely be either the proposed GMACS/MANIFEST spectrograph for the Giant Magellan Telescope or the OPTIMOS spectrograph for the European Extremely Large Telescope, depending on actual properties when built. The PFS spectrograph at Subaru would be next best and available considerably earlier, c. 2018; the proposed ngCFHT and SSST telescopes would have similar capabilities but start later. Other key options, in order of increasing total time required, are the WFOS spectrograph at TMT, MOONS at the VLT, and DESI at the Mayall 4 m telescope (or the similar 4MOST and WEAVE projects); of these, only DESI, MOONS, and PFS are expected to be available before 2020. Table 2-3 of this white paper summarizes the observation time required at each facility for strawman training samples. To attain secure redshift measurements for a high fraction of targeted objects and cover the full redshift span of future experiments, additional near-infrared spectroscopy will also be required; this is best done from space, particularly with WFIRST-2.4 and JWST; Calibration: The first several moments of redshift distributions (the mean, RMS redshift dispersion, etc.), must be known to high accuracy for cosmological constraints not to be systematics-dominated (equivalently, the moments of the distribution of differences between photometric and true redshifts could be determined instead). The ultimate goal of calibration is to characterize these moments for every subsample used in analyses - i.e., to minimize the uncertainty in their mean redshift, RMS dispersion, etc. – rather than to make the moments the

  6. Effect of phantom dark energy on the holographic thermalization

    E-Print Network [OSTI]

    Xiao-Xiong Zeng; Xin-Yun Hu; Li-Fang Li

    2015-03-16

    Gravitational collapse of a shell of charged dust surrounded by the phantom dark energy is probed by the minimal area surface, which is dual to probe the thermalization in the boundary quantum field by expectation values of Wilson loop in the framework of the AdS/CFT correspondence. We investigated mainly the effect of the phantom dark energy parameter and chemical potential on the thermalization. The result shows that the smaller the phantom dark energy parameter is, the easier the plasma thermalizes as the chemical potential is fixed, and the larger the chemical potential is, the harder the plasma thermalizes as the dark energy parameter is fixed. We get the fitting function of the thermalization curve and with it, the thermalization velocity and thermalization acceleration are discussed.

  7. Stable dark energy stars: An alternative to black holes?

    E-Print Network [OSTI]

    Lobo, F S N

    2008-01-01

    In this work, a generalization of the Mazur-Mottola gravastar model is explored, by considering a matching of an interior solution governed by the dark energy equation of state, $\\omega\\equiv p/ \\rhoenergy is a possible candidate.

  8. Stable dark energy stars: An alternative to black holes?

    E-Print Network [OSTI]

    Francisco S. N. Lobo

    2006-12-05

    In this work, a generalization of the Mazur-Mottola gravastar model is explored, by considering a matching of an interior solution governed by the dark energy equation of state, $\\omega\\equiv p/ \\rhoenergy is a possible candidate.

  9. About the Geometric Solution to the Problems of Dark Energy

    E-Print Network [OSTI]

    Miguel Angel García-Aspeitia

    2011-02-06

    In this paper is proposed a geometric solution to the dark energy, assuming that the space can be divided into regions of size $\\sim L_{p}$ and energy $\\sim E_{p}$. Significantly this assumption generate a energy density similar to the energy density observed for the vaccum energy, the correct solution for the coincidence problem and the state equation characteristic of quintessence in the comoving coordinates. Similarly is studied the ultraviolet and infrarred limits and the amount of dark energy in the Universe.

  10. Properties of holographic dark energy at the Hubble length

    E-Print Network [OSTI]

    Ivan Duran; Luca Parisi

    2013-01-15

    We consider holographic cosmological models of dark energy in which the infrared cutoff is set by the Hubble's radius. We show that any interacting dark energy model, regardless of its detailed form, can be recast as a non interacting model in which the holographic parameter $c^{2}$ evolves slowly with time. Two specific cases are analyzed. We constrain the parameters of both models with observational data, and show that they can be told apart at the perturbative level.

  11. New Light on Dark Energy (LBNL Science at the Theater)

    ScienceCinema (OSTI)

    Linder, Eric; Ho, Shirly; Aldering, Greg; Fraiknoi, Andrew

    2011-06-08

    A panel of Lab scientists ? including Eric Linder, Shirly Ho, and Greg Aldering ? along with Andrew Fraiknoi, the Bay Area's most popular astronomy explainer, gathered at the Berkeley Repertory Theatre on Monday, April 25, 2011, for a discussion about "New Light on Dark Energy." Topics will include hunting down Type 1a supernovae, measuring the universe using baryon oscillation, and whether dark energy is the true driver of the universe.

  12. Dark energy domination in the local flow of giant galaxies

    E-Print Network [OSTI]

    Chernin, A D; Karachentsev, I D

    2015-01-01

    A dozen most luminous galaxies at distances up to 10 Mpc from the Local Group are moving away from the group forming the local expansion flow of giants. We use recent Hubble Space Telescope data on the local giants and their numerous fainter companions to study the dynamical structure and evolutionary trends of the flow. It is demonstrated that the dynamics of the flow is dominated by local dark energy. Keywords: Galaxies, groups and clusters of galaxies; local flows of galaxies; dark energy.

  13. Vacuum quantum fluctuation energy in expanding universe and dark energy

    E-Print Network [OSTI]

    Shun-Jin Wang

    2014-10-27

    This article is based on the Planckon densely piled vacuum model and the principle of cosmology. With the Planck era as initial conditions and including the early inflation, we have solved the Einstein-Friedmann equations to describe the evolution of the universe. The results are: 1) the ratio of the dark energy density to the vacuum quantum fluctuation energy density is $\\frac{{{\\rho }_{de}}}{{{\\rho }_{vac}}}\\sim{{(\\frac{{{t}_{P}}}{{{T}_{0}}})}^{2}}\\sim{{10}^{-122}} $; 2) at the inflation time ${{t}_{\\inf }}={{10}^{-35}}s$, the calculated universe radiation energy density is $\\rho ({{t}_{\\inf }})\\sim{{10}^{-16}}{{\\rho }_{vac}}$ and the corresponding temperature is ${{E}_{c}}\\sim{{10}^{15}}GeV$ consistent with the GUT phase transition temperature; 3) the expanding universe with vacuum as its environment is a non-equilibrium open system constantly exchanging energy with vacuum; during its expansion, the Planckons in the universe lose quantum fluctuation energy and create the cosmic expansion quanta-cosmons, the energy of cosmons is the lost part of the vacuum quantum fluctuation energy and contributes to the universe energy with the calculated value ${{E}_{\\cos mos}}={{10}^{22}}{{M}_{\\otimes }}{{c}^{2}}$ (where ${{M}_{\\otimes }}$ is solar mass); 4) the total energy of the universe, namely the negative gravity energy plus the positive universe energy is zero; 5) the negative gravity potential and the gravity acceleration related to the creation of cosmons are derived with the nature of outward repulsive force, indicating that the cosmon may be the candidate of the dark energy quantum; 6) both the initial Planck era solution and the infinite asymptotic solution of the Einstein-Friedman equations are unstable: the former tends to expand and the latter tends to shrink, so that the Einstein-Friedman universe will undergo a cyclic evolution of successive expansion and shrinking.

  14. Probing Dark Energy models with neutrons

    E-Print Network [OSTI]

    G. Pignol

    2015-03-11

    There is a deep connection between cosmology -- the science of the infinitely large --and particle physics -- the science of the infinitely small. This connection is particularly manifest in neutron particle physics. Basic properties of the neutron -- its Electric Dipole Moment and its lifetime -- are intertwined with baryogenesis and nucleosynthesis in the early Universe. I will cover this topic in the first part, that will also serve as an introduction (or rather a quick recap) of neutron physics and Big Bang cosmology. Then, the rest of the manuscript will be devoted to a new idea: using neutrons to probe models of Dark Energy. In the second part, I will present the chameleon theory: a light scalar field accounting for the late accelerated expansion of the Universe, which interacts with matter in such a way that it does not mediate a fifth force between macroscopic bodies. However, neutrons can alleviate the chameleon mechanism and reveal the presence of the scalar field with properly designed experiments. In the third part, I will describe a recent experiment performed with a neutron interferometer at the Institut Laue Langevin that sets already interesting constraints on the chameleon theory. Last, the chameleon field can be probed by measuring the quantum states of neutrons bouncing over a mirror. In the fourth part I will present the status and prospects of the GRANIT experiment at the ILL.

  15. Probing Dark Energy models with neutrons

    E-Print Network [OSTI]

    G. Pignol

    2015-09-16

    There is a deep connection between cosmology -- the science of the infinitely large --and particle physics -- the science of the infinitely small. This connection is particularly manifest in neutron particle physics. Basic properties of the neutron -- its Electric Dipole Moment and its lifetime -- are intertwined with baryogenesis and nucleosynthesis in the early Universe. I will cover this topic in the first part, that will also serve as an introduction (or rather a quick recap) of neutron physics and Big Bang cosmology. Then, the rest of the manuscript will be devoted to a new idea: using neutrons to probe models of Dark Energy. In the second part, I will present the chameleon theory: a light scalar field accounting for the late accelerated expansion of the Universe, which interacts with matter in such a way that it does not mediate a fifth force between macroscopic bodies. However, neutrons can alleviate the chameleon mechanism and reveal the presence of the scalar field with properly designed experiments. In the third part, I will describe a recent experiment performed with a neutron interferometer at the Institut Laue Langevin that sets already interesting constraints on the chameleon theory. Last, the chameleon field can be probed by measuring the quantum states of neutrons bouncing over a mirror. In the fourth part I will present the status and prospects of the GRANIT experiment at the ILL.

  16. Dark River, Minnesota: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTIONRobertsdale, Alabama (UtilityInstruments Inc JumpIowa: EnergyDark River, Minnesota: Energy Resources

  17. Modified holographic Ricci dark energy coupled to interacting relativistic and non-relativistic dark matter in the nonflat universe

    E-Print Network [OSTI]

    En-Kun Li; Yu Zhang; Jin-Ling Geng

    2014-12-16

    The modified holographic Ricci dark energy coupled to interacting relativistic and non-relativistic dark matter is considered in the nonflat Friedmann-Robertson-Walker universe. Through examining the deceleration parameter, one can find that the transition time of the Universe from decelerating to accelerating phase in the interacting holographic Ricci dark energy model is close to that in the $\\Lambda$ cold dark matter model. The evolution of modified holographic Ricci dark energy's state parameter and the evolution of dark matter and dark energy's densities shows that the dark energy holds the dominant position from the near past to the future. By studying the statefinder diagnostic and the evolution of the total pressure, one can find that this model could explain the Universe's transition from the radiation to accelerating expansion stage through the dust stage. According to the $Om$ diagnostic, it is easy to find that when the interaction is weak and the proportion of relativistic dark matter in total dark matter is small, this model is phantom-like. Through our studying, we find the interaction and the relativistic dark matter's proportion all have great influence on the evolution of the Universe.

  18. Geodetic Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History View New PagesSustainable UrbanKentucky: EnergyGateway EditOpenTechniques Jump2004)2005) |Survey

  19. Linear Perturbation constraints on Multi-coupled Dark Energy

    E-Print Network [OSTI]

    Arpine Piloyan; Valerio Marra; Marco Baldi; Luca Amendola

    2014-01-12

    The Multi-coupled Dark Energy (McDE) scenario has been recently proposed as a specific example of a cosmological model characterized by a non-standard physics of the dark sector of the universe that nevertheless gives an expansion history which does not significantly differ from the one of the standard $\\Lambda $CDM model. In this work, we present the first constraints on the McDE scenario obtained by comparing the predicted evolution of linear density perturbations with a large compilation of recent data sets for the growth rate $f\\sigma_{8}$, including 6dFGS, LRG, BOSS, WiggleZ and VIPERS. Confirming qualitative expectations, growth rate data provide much tighter bounds on the model parameters as compared to the extremely loose bounds that can be obtained when only the background expansion history is considered. In particular, the $95\\%$ confidence level on the coupling strength $|\\beta |$ is reduced from $|\\beta |\\leq 83$ (background constraints only) to $|\\beta |\\leq 0.88$ (background and linear perturbation constraints). We also investigate how these constraints further improve when using data from future wide-field surveys such as supernova data from LSST and growth rate data from Euclid-type missions. In this case the $95\\%$ confidence level on the coupling further reduce to $|\\beta |\\leq 0.85$. Such constraints are in any case still consistent with a scalar fifth-force of gravitational strength, and we foresee that tighter bounds might be possibly obtained from the investigation of nonlinear structure formation in McDE cosmologies.[Abridged

  20. Interacting cosmic fluids and phase transitions under a holographic modeling for dark energy

    E-Print Network [OSTI]

    Samuel Lepe; Francisco Pena

    2015-11-23

    We discuss the consequences of possible sign changes of the $Q$-function which measures the energy transference between dark energy and dark matter. We investigate this scenario from a holographic perspective to modeling the dark energy by a linear-parametrization of the equation of state parameter denoted by $\\omega$. By imposing the strong constraint of the second law of thermodynamics, we show that sign changes of $Q$ due to the cosmic evolution imply changes in the temperatures of dark energy and dark matter, respectively. We also discuss the phase transitions, in the past and future, experienced by dark energy and dark matter (or, equivalently, the sign changes of their heat capacities).

  1. Interacting cosmic fluids and phase transitions under a holographic modeling for dark energy

    E-Print Network [OSTI]

    Lepe, Samuel

    2015-01-01

    We discuss the consequences of possible sign changes of the $Q$-function which measures the energy transference between dark energy and dark matter. We investigate this scenario from a holographic perspective to modeling the dark energy by a linear-parametrization of the equation of state parameter denoted by $\\omega$. By imposing the strong constraint of the second law of thermodynamics, we show that sign changes of $Q$ due to the cosmic evolution imply changes in the temperatures of dark energy and dark matter, respectively. We also discuss the phase transitions, in the past and future, experienced by dark energy and dark matter (or, equivalently, the sign changes of their heat capacities).

  2. DESI and other Dark Energy experiments in the era of neutrino mass measurements

    SciTech Connect (OSTI)

    Font-Ribera, Andreu; McDonald, Patrick; Mostek, Nick; Reid, Beth A.; Seo, Hee-Jong; Slosar, Anže E-mail: PVMcDonald@lbl.gov E-mail: BAReid@lbl.gov E-mail: anze@bnl.gov

    2014-05-01

    We present Fisher matrix projections for future cosmological parameter measurements, including neutrino masses, Dark Energy, curvature, modified gravity, the inflationary perturbation spectrum, non-Gaussianity, and dark radiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX, eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weak gravitational lensing (DES and LSST) constraints. The goal is to present a consistent set of projections, for concrete experiments, which are otherwise scattered throughout many papers and proposals. We include neutrino mass as a free parameter in most projections, as it will inevitably be relevant — DESI and other experiments can measure the sum of neutrino masses to ? 0.02 eV or better, while the minimum possible sum is ? 0.06 eV. We note that constraints on Dark Energy are significantly degraded by the presence of neutrino mass uncertainty, especially when using galaxy clustering only as a probe of the BAO distance scale (because this introduces additional uncertainty in the background evolution after the CMB epoch). Using broadband galaxy power becomes relatively more powerful, and bigger gains are achieved by combining lensing survey constraints with redshift survey constraints. We do not try to be especially innovative, e.g., with complex treatments of potential systematic errors — these projections are intended as a straightforward baseline for comparison to more detailed analyses.

  3. QCD nature of dark energy at finite temperature: cosmological implications

    E-Print Network [OSTI]

    K. Azizi; N. Katirci

    2015-06-23

    The Veneziano ghost field has been proposed as an alternative source of dark energy whose energy density is consistent with the cosmological observations. In this model, the energy density of QCD ghost field is expressed in terms of QCD degrees of freedom at zero temperature. We extend this model to finite temperature to search the model predictions from the late time to the early universe. We depict the variations of QCD parameters entering the calculations, dark energy density, equation of state, Hubble and deceleration parameters on temperature from zero to a critical temperature. We compare our results with the observations and theoretical predictions existing at different eras.It is found that this model safely define the universe from quark condensation up to now and its predictions are not in tension with those of the standard cosmology. The finite temperature ghost dark energy predictions on the Hubble parameter slightly better fit to observations compared to those of zero temperature.

  4. QCD nature of dark energy at finite temperature: cosmological implications

    E-Print Network [OSTI]

    Azizi, K

    2015-01-01

    The Veneziano ghost field has been proposed as an alternative source of dark energy whose energy density is consistent with the cosmological observations. In this model, the energy density of QCD ghost field is expressed in terms of QCD degrees of freedom at zero temperature. We extend this model to finite temperature to search the model predictions from the late time to the early universe. We depict the variations of QCD parameters entering the calculations, dark energy density, equation of state, Hubble and deceleration parameters on temperature from zero to a critical temperature. We compare our results with the observations and theoretical predictions existing at different eras.It is found that this model safely define the universe from quark condensation up to now and its predictions are not in tension with those of the standard cosmology. The finite temperature ghost dark energy predictions on the Hubble parameter slightly better fit to observations compared to those of zero temperature.

  5. Reduction of Cosmological Data for the Detection of Time-varying Dark Energy Density

    E-Print Network [OSTI]

    Jason Dick; Lloyd Knox; Mike Chu

    2006-07-10

    We present a method for reducing cosmological data to constraints on the amplitudes of modes of the dark energy density as a function of redshift. The modes are chosen so that (1) one of them has constant density and (2) the others are non-zero only if there is time-variation in the dark energy density and (3) the amplitude errors for the time-varying modes are uncorrelated with each other. We apply our method to various combinations of three-year WMAP data, baryon acoustic oscillation data, the 'Gold' supernova data set, and the Supernova Legacy Survey data set. We find no significant evidence for a time-varying dark energy density or for non-zero mean curvature. Although by some measure the limits on four of the time-varying mode amplitudes are quite tight, they are consistent with the expectation that the dark energy density does not vary on timescales shorter than a Hubble time. Since we do not expect detectable time variation in these modes, our results should be viewed as a systematic error test which the data have passed. We discuss a procedure to identify modes with maximal signal-to-noise ratio.

  6. Accretions of Dark Matter and Dark Energy onto ($n+2$)-dimensional Schwarzschild Black Hole and Morris-Thorne Wormhole

    E-Print Network [OSTI]

    Ujjal Debnath

    2015-03-06

    We have studied accretion of the dark matter and dark energy onto of $(n+2)$-dimensional Schwarzschild black hole and Morris-Thorne wormhole. The mass and the rate of change of mass for $(n+2)$-dimensional Schwarzschild black hole and Morris-Thorne wormhole have been found. We have assumed some candidates of dark energy like holographic dark energy, new agegraphic dark energy, quintessence, tachyon, DBI-essence, etc. The black hole mass and the wormhole mass have been calculated in term of redshift when dark matter and above types of dark energies accrete onto them separately. We have shown that the black hole mass increases and wormhole mass decreases for holographic dark energy, new agegraphic dark energy, quintessence, tachyon accretion and the slope of increasing/decreasing of mass sensitively depends on the dimension. But for DBI-essence accretion, the black hole mass first increases and then decreases and the wormhole mass first decreases and then increases and the slope of increasing/decreasing of mass not sensitively depends on the dimension.

  7. Exploring a new interaction between dark matter and dark energy using the growth rate of structure

    E-Print Network [OSTI]

    Richarte, Martín G

    2015-01-01

    We present a phenomenological interaction with a scale factor power law form which leads to the appearance of two kinds of perturbed terms, a scale factor spatial variation along with perturbed Hubble expansion rate. We study both the background and the perturbation evolution within the parametrized post-Friedmann scheme, obtaining that the exchange of energy-momentum can flow from dark energy to dark matter in order to keep dark energy and dark matter densities well defined at all times. We combine several measures of the cosmic microwave background (WMAP9+Planck) data, baryon acoustic oscillation measurements, redshift-space distortion data, JLA sample of supernovae, and Hubble constant for constraining the coupling constant and the exponent provided both parametrized the interaction itself. The joint analysis of ${\\rm Planck+WMAP9+BAO}$ ${\\rm +RSD+JLA+HST}$ data seems to favor large coupling constant, $\\xi_c = 0.34403427_{- 0.18907353}^{+ 0.14430125}$ at 1 $\\sigma$ level, and prefers a power law interactio...

  8. A dark energy model alternative to generalized Chaplygin gas

    E-Print Network [OSTI]

    Hova, Hoavo

    2010-01-01

    We propose a new fluid model of dark energy for $-1 \\leq \\omega_{\\text{eff}} \\leq 0$ as an alternative to the generalized Chaplygin gas models. The energy density of dark energy fluid is severely suppressed during barotropic matter dominant epochs, and it dominates the universe evolution only for eras of small redshift. From the perspective of fundamental physics, the fluid is a tachyon field with a scalar potential flatter than that of power-law decelerated expansion. Different from the standard $\\Lambda\\text{CDM}$ model, the suggested dark energy model claims that the cosmic acceleration at present epoch can not continue forever but will cease in the near future and a decelerated cosmic expansion will recover afterwards.

  9. Fundamentalist physics: why Dark Energy is bad for Astronomy

    E-Print Network [OSTI]

    White, Simon D M

    2007-01-01

    Astronomers carry out observations to explore the diverse processes and objects which populate our Universe. High-energy physicists carry out experiments to approach the Fundamental Theory underlying space, time and matter. Dark Energy is a unique link between them, reflecting deep aspects of the Fundamental Theory, yet apparently accessible only through astronomical observation. Large sections of the two communities have therefore converged in support of astronomical projects to constrain Dark Energy. In this essay I argue that this convergence can be damaging for astronomy. The two communities have different methodologies and different scientific cultures. By uncritically adopting the values of an alien system, astronomers risk undermining the foundations of their own current success and endangering the future vitality of their field. Dark Energy is undeniably an interesting problem to attack through astronomical observation, but it is one of many and not necessarily the one where significant progress is mo...

  10. A dark energy model alternative to generalized Chaplygin gas

    E-Print Network [OSTI]

    Hoavo Hova; Huanxiong Yang

    2010-11-22

    We propose a new fluid model of dark energy for $-1 \\leq \\omega_{\\text{eff}} \\leq 0$ as an alternative to the generalized Chaplygin gas models. The energy density of dark energy fluid is severely suppressed during barotropic matter dominant epochs, and it dominates the universe evolution only for eras of small redshift. From the perspective of fundamental physics, the fluid is a tachyon field with a scalar potential flatter than that of power-law decelerated expansion. Different from the standard $\\Lambda\\text{CDM}$ model, the suggested dark energy model claims that the cosmic acceleration at present epoch can not continue forever but will cease in the near future and a decelerated cosmic expansion will recover afterwards.

  11. Future Supernovae observations as a probe of dark energy

    E-Print Network [OSTI]

    Jochen Weller; Andreas Albrecht

    2002-04-02

    We study the potential impact of improved future supernovae data on our understanding of the dark energy problem. We carefully examine the relative utility of different fitting functions that can be used to parameterize the dark energy models, and provide concrete reasons why a particular choice (based on a parameterization of the equation of state) is better in almost all cases. We discuss the details of a representative sample of dark energy models and show how future supernova observations could distinguish among these. As a specific example, we consider the proposed ``SNAP'' satellite which is planned to observe around 2000 supernovae. We show how a SNAP-class data set taken alone would be a powerful discriminator among a family of models that would be approximated by a constant equation of state for the most recent epoch of cosmic expansion. We show how this family includes most of the dark energy models proposed so far. We then show how an independent measurement of $\\Omega_{\\rm m}$ can allow SNAP to probe the evolution of the equation of state as well, allowing further discrimination among a larger class of proposed dark energy models. We study the impact of the satellite design parameters on this method to distinguish the models and compare SNAP to alternative measurements. We establish that if we exploit the full precision of SNAP it provides a very powerful probe.

  12. Fine Structure of Dark Energy and New Physics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jejjala, Vishnu; Kavic, Michael; Minic, Djordje

    2007-01-01

    Following our recent work on the cosmological constant problem, in this letter we make a specific proposal regarding the fine structure (i.e., the spectrum) of dark energy. The proposal is motivated by a deep analogy between the blackbody radiation problem, which led to the development of quantum theory, and the cosmological constant problem, for which we have recently argued calls for a conceptual extension of the quantum theory. We argue that the fine structure of dark energy is governed by a Wien distribution, indicating its dual quantum and classical nature. We discuss observational consequences of such a picture of darkmore »energy and constrain the distribution function.« less

  13. A low-$z$ test for interacting dark energy

    E-Print Network [OSTI]

    Goncalves, R S; Alcaniz, J S

    2015-01-01

    A non-minimal coupling between the dark matter and dark energy components may offer a way of solving the so-called coincidence problem. In this paper we propose a low-$z$ test for such hypothesis using measurements of the gas mass fraction $f_{\\rm{gas}}$ in relaxed and massive galaxy clusters. The test applies to any model whose dilution of dark matter is modified with respect to the standard $a^{-3}$ scaling, as usual in interacting models, where $a$ is the cosmological scale factor. We apply the test to current $f_{\\rm{gas}}$ data and perform Monte Carlo simulations to forecast the necessary improvements in number and accuracy of upcoming observations to detect a possible interaction in the cosmological dark sector. Our results show that improvements in the present relative error $\\sigma_{\\rm{gas}}/f_{\\rm{gas}}$ are more effective to achieve this goal than an increase in the size of the $f_{\\rm{gas}}$ sample.

  14. Model-independent constraints on dark energy and modified gravity with the SKA

    E-Print Network [OSTI]

    Zhao, Gong-Bo; Maartens, Roy; Santos, Mario; Raccanelli, Alvise

    2015-01-01

    Employing a nonparametric approach of the principal component analysis (PCA), we forecast the future constraint on the equation of state $w(z)$ of dark energy, and on the effective Newton constant $\\mu(k,z)$, which parameterise the effect of modified gravity, using the planned SKA HI galaxy survey. Combining with the simulated data of Planck and Dark Energy Survey (DES), we find that SKA Phase 1 (SKA1) and SKA Phase 2 (SKA2) can well constrain $3$ and $5$ eigenmodes of $w(z)$ respectively. The errors of the best measured modes can be reduced to 0.04 and 0.023 for SKA1 and SKA2 respectively, making it possible to probe dark energy dynamics. On the other hand, SKA1 and SKA2 can constrain $7$ and $20$ eigenmodes of $\\mu(k,z)$ respectively within 10\\% sensitivity level. Furthermore, 2 and 7 modes can be constrained within sub percent level using SKA1 and SKA2 respectively. This is a significant improvement compared to the combined datasets without SKA.

  15. Dark Energy Cosmology with the Alternative Cosmic Microwave Background Data

    E-Print Network [OSTI]

    Hao Wei

    2011-04-19

    Recently, in a series of works by Liu and Li (L&L), they claimed that there exists a timing asynchrony of $-25.6\\,$ms between the spacecraft attitude and radiometer output timestamps in the original raw WMAP time-ordered data (TOD). L&L reprocessed the WMAP data while the aforementioned timing asynchrony has been corrected, and they obtained an alternative CMB map in which the quadrupole dropped to nearly zero. In the present work, we try to see the implications to dark energy cosmology if L&L are right. While L&L claimed that there is a bug in the WMAP pipeline which leads to significantly different cosmological parameters, an interesting question naturally arises, namely, how robust is the current dark energy cosmology with respect to systematic errors and bugs? So, in this work, we adopt the alternative CMB data of L&L as a strawman to study the robustness of dark energy predictions.

  16. A Tracker Solution for a Holographic Dark Energy Model

    E-Print Network [OSTI]

    Hui Li; Zong-kuan Guo; Yuan-zhong Zhang

    2006-02-23

    We investigate a kind of holographic dark energy model with the future event horizon the IR cutoff and the equation of state -1. In this model, the constraint on the equation of state automatically specifies an interaction between matter and dark energy. With this interaction included, an accelerating expansion is obtained as well as the transition from deceleration to acceleration. It is found that there exists a stable tracker solution for the numerical parameter $d>1$, and $d$ smaller than one will not lead to a physical solution. This model provides another possible phenomenological framework to alleviate the cosmological coincidence problem in the context of holographic dark energy. Some properties of the evolution which are relevant to cosmological parameters are also discussed.

  17. A divergence-free parametrization for dynamical dark energy

    E-Print Network [OSTI]

    Ozgur Akarsu; Tekin Dereli; J. Alberto Vazquez

    2015-06-30

    We introduce a new parametrization for the dark energy, led by the same idea to the linear expansion of the equation of state in scale factor $a$ and in redshift $z$, which diverges neither in the past nor future and contains the same number of degrees of freedom with the former two. We present constraints of the cosmological parameters using the most updated baryon acoustic oscillation (BAO) measurements along with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. This new parametrization allowed us to carry out successive observational analyses by decreasing its degrees of freedom systematically until ending up with a dynamical dark energy model that has the same number of parameters with $\\Lambda$CDM. We found that the dark energy source with a dynamical equation of state parameter equal $-2/3$ at the early universe and $-1$ today fits the data slightly better than $\\Lambda$.

  18. Strong gravitational lensing constraints on holographic dark energy

    E-Print Network [OSTI]

    Cui, Jing-Lei; Zhang, Jing-Fei; Zhang, Xin

    2015-01-01

    Strong gravitational lensing (SGL) has provided an important tool for probing galaxies and cosmology. In this paper, we use the SGL data to constrain the holographic dark energy model, as well as models that have the same parameter number, such as the $w$CDM and Ricci dark energy models. We find that only using SGL is difficult to effectively constrain the model parameters. However, when the SGL data are combined with CBS (CMB+BAO+SN) data, the reasonable estimations can be given and the constraint precision is improved to a certain extent, relative to the case of CBS only. Therefore, SGL is an useful way to tighten constraints on model parameters.

  19. Dark energy and non-linear power spectrum

    E-Print Network [OSTI]

    Sang Gyu Biern; Jinn-Ouk Gong

    2015-06-29

    We investigate the effects of homogeneous general dark energy on the non-linear matter perturbation in fully general relativistic context. The equation for the density contrast contains even at linear order new contributions which are non-zero for general dark energy. Taking into account the next-leading-order corrections, we derive the total power spectrum in real and redshift spaces. We find that the observable galaxy power spectrum deviates from the LambdaCDM spectrum, which is nearly identical to that in the Einstein-de Sitter universe, and the relative difference is about 10% on a scale of the baryon acoustic oscillations.

  20. QCD nature of dark energy at finite temperature: cosmological implications

    E-Print Network [OSTI]

    K. Azizi; N. Katirci

    2015-09-20

    The Veneziano ghost field has been proposed as an alternative source of dark energy whose energy density is consistent with the cosmological observations. In this model, the energy density of QCD ghost field is expressed in terms of QCD degrees of freedom at zero temperature. We extend this model to finite temperature to search the model predictions from the late time to the early universe. We depict the variations of QCD parameters entering the calculations, dark energy density, equation of state, Hubble and deceleration parameters on temperature from zero to a critical temperature. We compare our results with the observations and theoretical predictions existing at different eras. It is found that this model safely define the universe from quark condensation up to now and its predictions are not in tension with those of the standard cosmology. The EoS parameter of dark energy is obtained to be $-1/3$ in the presence of radiation and $-1$ at late time. The finite temperature ghost dark energy predictions on the Hubble parameter slightly better fit to observations compared to those of zero temperature.

  1. Gravastars with Dark Energy Evolving to Naked Singularity

    E-Print Network [OSTI]

    R. Chan; M. F. A. da Silva; P. Senna; J. F. Villas da Rocha

    2011-11-17

    We consider a gravastar model made of anisotropic dark energy with an infinitely thin spherical shell of a perfect fluid with the equation of state $p = (1-\\gamma)\\sigma$ with an external de Sitter-Schwarzschild region. It is found that in some cases the models represent the "bounded excursion" stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes or naked singularities. An interesting result is that we can have black hole and stable gravastar formation even with an interior and a shell constituted of dark and repulsive dark energy, as also shown in previous work. Besides, in three cases we have a dynamical evolution to a black hole (for $\\Lambda=0$) or to a naked singularity (for $\\Lambda > 0$). This is the first time in the literature that a naked singularity emerges from a gravastar model.

  2. Thermodynamics of viscous dark energy in an RSII braneworld

    E-Print Network [OSTI]

    M. R. Setare; A. Sheykhi

    2011-03-05

    We show that for an RSII braneworld filled with interacting viscous dark energy and dark matter, one can always rewrite the Friedmann equation in the form of the first law of thermodynamics, $dE=T_hdS_h+WdV$, at apparent horizon. In addition, the generalized second law of thermodynamics can fulfilled in a region enclosed by the apparent horizon on the brane for both constant and time variable 5-dynamical Newton's constant $G_5$. These results hold regardless of the specific form of the dark energy. Our study further support that in an accelerating universe with spatial curvature, the apparent horizon is a physical boundary from the thermodynamical point of view.

  3. 2010 Texas Jurisdiction Energy Code Adoption Survey 

    E-Print Network [OSTI]

    2010-01-01

    Deer Park 2006 Del Rio 2003 Denton 2006 Desoto 2003 Devine 2003 Duncanville 2006 Eagle Pass 2009 Edinburg 2006 El Paso 2009 Euless 2003 ESL-TR-10-06-01 2010 Texas Jurisdiction Energy Code Adoption Survey 2 ESL Survey of Texas Building Codes... Lubbock 2000 Lufkin None New Braunfels 2006 Mansfield 2006 McAllen 2006 McKinney 2006 Mesquite 2006 Midland 2009 Mission None ESL-TR-10-06-01 2010 Texas Jurisdiction Energy Code Adoption Survey 3 ESL Survey of Texas Building Codes ? Completed...

  4. Cosmology with moving dark energy and the CMB quadrupole

    E-Print Network [OSTI]

    Jose Beltran Jimenez; Antonio L. Maroto

    2007-07-11

    We study the consequences of a homogeneous dark energy fluid having a non-vanishing velocity with respect to the matter and radiation large-scale rest frames. We consider homogeneous anisotropic cosmological models with four fluids (baryons, radiation, dark matter and dark energy) whose velocities can differ from each other. Performing a perturbative calculation up to second order in the velocities, we obtain the contribution of the anisotropies generated by the fluids motion to the CMB quadrupole and compare with observations. We also consider the exact problem for arbitrary velocities and solve the corresponding equations numerically for different dark energy models. We find that models whose equation of state is initially stiffer than radiation, as for instance some tracking models, are unstable against velocity perturbations, thus spoiling the late-time predictions for the energy densities. In the case of scaling models, the contributions to the quadrupole can be non-negligible for a wide range of initial conditions. We also consider fluids moving at the speed of light (null fluids) with positive energy and show that, without assuming any particular equation of state, they generically act as a cosmological constant at late times. We find the parameter region for which the models considered could be compatible with the measured (low) quadrupole.

  5. Exploring a new interaction between dark matter and dark energy using the growth rate of structure

    E-Print Network [OSTI]

    Martín G. Richarte; Lixin Xu

    2015-06-08

    We present a phenomenological interaction with a scale factor power law form which leads to the appearance of two kinds of perturbed terms, a scale factor spatial variation along with perturbed Hubble expansion rate. We study both the background and the perturbation evolution within the parametrized post-Friedmann scheme, obtaining that the exchange of energy-momentum can flow from dark energy to dark matter in order to keep dark energy and dark matter densities well defined at all times. We combine several measures of the cosmic microwave background (WMAP9+Planck) data, baryon acoustic oscillation measurements, redshift-space distortion data, JLA sample of supernovae, and Hubble constant for constraining the coupling constant and the exponent provided both parametrized the interaction itself. The joint analysis of ${\\rm Planck+WMAP9+BAO}$ ${\\rm +RSD+JLA+HST}$ data seems to favor large coupling constant, $\\xi_c = 0.34403427_{- 0.18907353}^{+ 0.14430125}$ at 1 $\\sigma$ level, and prefers a power law interaction with a negative exponent, thus $\\beta= -0.50863232_{- 0.40923857}^{+ 0.48424166}$ at 1 $\\sigma$ level. The CMB temperature power spectrum indicates that a large coupling constant produces a shift of the acoustic peaks and affects their amplitudes at lower multipoles. In addition, a larger $\\beta$ exponent generates a shift of the acoustic peaks, pointing a clear deviation with respect to the concordance model. The matter power spectrum are sensitive to the variation of the coupling constant and the $\\beta$ exponent. In this context, the interaction alters the scale of matter and radiation equality and pushes it away from the present era, which in turn generates a shift of the turnover point toward to smaller scale.

  6. Growth of matter perturbations in clustered holographic dark energy cosmologies

    E-Print Network [OSTI]

    Mehrabi, Ahmad; Malekjani, Mohammad; Davari, Zahra

    2015-01-01

    We investigate the growth of matter fluctuations in holographic dark energy cosmologies. First we use an overall statistical analysis involving the latest observational data in order to place constraints on the cosmological parameters. Then we test the range of validity of the holographic dark energy models at the perturbation level and its variants from the concordance $\\Lambda$ cosmology. Specifically, we provide a new analytical approach in order to derive, for the first time, the growth index of matter perturbations. Considering a homogeneous holographic dark energy we find that the growth index is $\\gamma \\approx \\frac{4}{7}$ which is somewhat larger ($\\sim 4.8\\%$) than that of the usual $\\Lambda$ cosmology, $\\gamma^{(\\Lambda)}\\approx \\frac{6}{11}$. Finally, if we allow clustering in the holographic dark energy models then the asymptotic value of the growth index is given in terms of the effective sound speed $c_{\\rm e}$, namely $\\gamma \\approx \\frac{3(1-c_{\\rm e})}{7}$.

  7. Constraints on the redshift dependence of the dark energy potential

    E-Print Network [OSTI]

    Joan Simon; Licia Verde; Raul Jimenez

    2004-12-13

    We develop a formalism to characterize the redshift evolution of the dark energy potential. Our formalism makes use of quantities similar to the Horizon-flow parameters in inflation and is general enough that can deal with multiscalar quintessence scenarios, exotic matter components, and higher order curvature corrections to General Relativity. We show how the shape of the dark energy potential can be recovered non parametrically using this formalism and we present approximations analogous to the ones relevant to slow-roll inflation. Since presently available data do not allow a non-parametric and exact reconstruction of the potential, we consider a general parametric description. This reconstruction can also be used in other approaches followed in the literature (e.g., the reconstruction of the redshift evolution of the dark energy equation of state w(z)). Using observations of passively evolving galaxies and supernova data we derive constraints on the dark energy potential shape in the redshift range 0.1 < z < 1.8. Our findings show that at the 1sigma level the potential is consistent with being constant, although at the same level of confidence variations cannot be excluded with current data. We forecast constraints achievable with future data from the Atacama Cosmology Telescope.

  8. Evolution of entropic dark energy and its phantom nature

    E-Print Network [OSTI]

    Mathew, Titus K; J, Shejeelammal

    2015-01-01

    Assuming the form of the entropic dark energy as arises form the surface term in the Einstein-Hilbert's action, it's evolution were analyzed in an expanding flat universe. The model parameters were evaluated by constraining model using the Union data on Type Ia supernovae. We found that the model predicts an early decelerated phase and a later accelerated phase at the background level. The evolution of the Hubble parameter, dark energy density, equation of state parameter and deceleration parameter were obtained. The model is diagnosed with $Om$ parameter. The model is hardly seems to be supporting the linear perturbation growth for the structure formation. We also found that the entropic dark energy shows phantom nature for redshifts $z<0.257.$ During the phantom epoch, the model predicts big-rip effect at which both the scale factor of expansion and the dark energy density become infinitely large and the big rip time is found to be around 36 Giga Years from now.

  9. Cold dark matter halos in Multi-coupled Dark Energy cosmologies: structural and statistical properties

    E-Print Network [OSTI]

    Baldi, Marco

    2014-01-01

    The recently proposed Multi-coupled Dark Energy (McDE) scenario - characterised by two distinct Cold Dark Matter (CDM) particle species with opposite couplings to a Dark Energy scalar field - introduces a number of novel features in the small-scale dynamics of cosmic structures, most noticeably the simultaneous existence of both attractive and repulsive fifth-forces. Such small-scale features are expected to imprint possibly observable footprints on nonlinear cosmic structures, that might provide a direct way to test the scenario. In order to unveil such footprints, we have performed the first suite of high-resolution N-body simulations of McDE cosmologies, covering the coupling range $|\\beta |\\leq 1$. We find that for coupling values corresponding to fifth-forces weaker than standard gravity, the impact on structure formation is very mild, thereby showing a new type of screening mechanism for long-range scalar interactions. On the contrary, for fifth-forces comparable to or stronger than standard gravity a n...

  10. Gravitational centre of mass and localization of dark energy

    E-Print Network [OSTI]

    Maluf, J W

    2015-01-01

    We analyse the expression for the centre of mass density of the gravitational field in the context of the teleparallel equivalent of general relativity. The purpose is to investigate the localization of dark energy in the three-dimensional space, induced by a cosmological constant in a simple Schwarzschild-de Sitter space-time. We also investigate the gravitational centre of mass density in a particular model of dark matter, in the space-time of a point massive particle and in an arbitrary space-time with axial symmetry. The results are plausible, and lead to the notion of gravitational centre of mass distribution function.

  11. Thermodynamic descriptions of Polytropic gas and its viscous type as the dark energy candidates

    E-Print Network [OSTI]

    Moradpour, H

    2015-01-01

    In this paper, at first, we focus on a FRW universe in which the dark energy candidate satisfies the Polytropic equation of state and study thermodynamics of dark energy. Bearing the thermal fluctuation theorem in mind, we establish a relation between the thermal fluctuation of system and mutual interaction between the dark energy and dark matter. Generalization to a viscous Polytropic gas is also investigated. We point to a condition for decaying dark energy candidate into the dark matter needed for alleviating coincidence problem. The effects of dark energy candidates and their interactions with other parts of cosmos on the horizon entropy as well as the second law of thermodynamics are also addressed. Our study signals us to two correction terms besides the Bekenstein entropy which carry the information of the dark energy candidate, its interaction with other parts of cosmos and its viscosity.

  12. The Future of the Local Large Scale Structure: the roles of Dark Matter and Dark Energy

    E-Print Network [OSTI]

    Yehuda Hoffman; Ofer Lahav; Gustavo Yepes; Yaniv Dover

    2007-10-10

    We study the distinct effects of Dark Matter and Dark Energy on the future evolution of nearby large scale structures using constrained N-body simulations. We contrast a model of Cold Dark Matter and a Cosmological Constant (LCDM) with an Open CDM (OCDM) model with the same matter density Omega_m =0.3 and the same Hubble constant h=0.7. Already by the time the scale factor increased by a factor of 6 (29 Gyr from now in LCDM; 78 Gyr from now in OCDM) the comoving position of the Local Group is frozen. Well before that epoch the two most massive members of the Local Group, the Milky Way and Andromeda, will merge. However, as the expansion rates of the scale factor in the two models are different, the Local Group will be receding in physical coordinates from Virgo exponentially in a LCDM model and at a roughly constant velocity in an OCDM model. More generally, in comoving coordinates the future large scale structure will look like a sharpened image of the present structure: the skeleton of the cosmic web will remain the same, but clusters will be more `isolated' and the filaments will become thinner. This implies that the long-term fate of large scale structure as seen in comoving coordinates is determined primarily by the matter density. We conclude that although the LCDM model is accelerating at present due to its Dark Energy component while the OCDM model is non accelerating, their large scale structure in the future will look very similar in comoving coordinates.

  13. Growth of Cosmic Structure: Probing Dark Energy Beyond Expansion

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Huterer, Dragan; Kirkby, David; Bean, Rachel; Connolly, Andrew; Dawson, Kyle; Dodelson, Scott; University of Chicago, Department of Physics & Astrophysics, Chicago, IL; Evrard, August; Jain, Bhuvnesh; Jarvis, Michael; et al

    2014-03-15

    The quantity and quality of cosmic structure observations have greatly accelerated in recent years, and further leaps forward will be facilitated by imminent projects. These will enable us to map the evolution of dark and baryonic matter density fluctuations over cosmic history. The way that these fluctuations vary over space and time is sensitive to several pieces of fundamental physics: the primordial perturbations generated by GUT-scale physics; neutrino masses and interactions; the nature of dark matter and dark energy. We focus on the last of these here: the ways that combining probes of growth with those of the cosmic expansionmore »such as distance-redshift relations will pin down the mechanism driving the acceleration of the Universe.« less

  14. Growth of Cosmic Structure: Probing Dark Energy Beyond Expansion

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Huterer, Dragan [University of Michigan, Department of Physics Ann Harbor, MI (United States); Kirkby, David [UC Irvine, Department of Physics and Astronomy, CA (United States); Bean, Rachel [Cornell University, Department of Astronomy, Ithaca, NY (United States); Connolly, Andrew [University of Washington, Department of Astronomy, Seattle, WA (United States); Dawson, Kyle [University of Utah, Department of Physics & Astronomy, Salt Lake City, UT (United States); Dodelson, Scott [Fermi National Accelerator Laboratory, Fermilab Center for Particle Astrophysics, Batavia, IL (United States); University of Chicago, Department of Physics & Astrophysics, Chicago, IL (United States); Evrard, August [University of Michigan, Department of Physics Ann Harbor, MI (United States); Jain, Bhuvnesh [University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, PA (United States); Jarvis, Michael [University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, PA (United States); Linder, Eric [Lawrence Berkeley National Laboratory, Physics Division, Berkeley, CA (United States); Mandelbaum, Rachel [Carnegie Mellon University, Department of Physics, Pittsburgh, PA (United States); May, Morgan [Brookhaven National Laboratory (BNL), Upton, NY (United States); Raccanelli, Alvise [California Institute of Technology, NASA Jet Propulsion Laboratory, Pasadena, CA (United States); Reid, Beth [Lawrence Berkeley National Laboratory, Physics Division, Berkeley, CA (United States); Rozo, Eduardo [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Schmidt, Fabian [Princeton University, Department of Astrophysical Sciences, Princeton, NJ (United States); Max-Planck-Insitute for Astrophysics, Garching (Germany); Sehgal, Neelima [Stony Brook University, NY (United States); Slosar, Anze [Brookhaven National Laboratory (BNL), Upton, NY (United States); Van Engelen, Alex [Stony Brook University, NY (United States); Wu, Hao-Yi [University of Michigan, Department of Physics, Ann Harbor, MI (United States); Zhao, Gongbo [Chinese Academy of Science, National Astronomy Observatories, Beijing (China)

    2015-03-01

    The quantity and quality of cosmic structure observations have greatly accelerated in recent years, and further leaps forward will be facilitated by imminent projects. These will enable us to map the evolution of dark and baryonic matter density fluctuations over cosmic history. The way that these fluctuations vary over space and time is sensitive to several pieces of fundamental physics: the primordial perturbations generated by GUT-scale physics; neutrino masses and interactions; the nature of dark matter and dark energy. We focus on the last of these here: the ways that combining probes of growth with those of the cosmic expansion such as distance-redshift relations will pin down the mechanism driving the acceleration of the Universe.

  15. Resource Letter: Dark Energy and the Accelerating Universe

    E-Print Network [OSTI]

    Eric V. Linder

    2007-05-28

    This Resource Letter provides a guide to the literature on dark energy and the accelerating universe. It is intended to be of use to researchers, teachers, and students at several levels. Journal articles, books, and websites are cited for the following topics: Einstein's cosmological constant, quintessence or dynamical scalar fields, modified cosmic gravity, relations to high energy physics, cosmological probes and observations, terrestrial probes, calculational tools and parameter estimation, teaching strategies and educational resources, and the fate of the universe.

  16. Constraining the dark energy with Ly-alpha forest

    E-Print Network [OSTI]

    Uros Seljak; Rachel Mandelbaum; Patrick McDonald

    2002-12-15

    Statistical properties of gas absorption in high redshift quasars such as power spectrum and bispectrum allow one to determine the evolution of structure over the redshift range 2energy to higher redshift and determine the presence of dark energy if Omega_de>0.1-0.2 at z>2. In combination with low redshift studies one can place useful limits on the time evolution of the equation of state.

  17. Ultra-Low-Energy Germanium Detector for Neutrino-Nucleus Coherent Scattering and Dark Matter Searches

    E-Print Network [OSTI]

    Henry T. Wong

    2008-03-01

    The status and plans of a research program on the development of ultra-low-energy germanium detectors with sub-keV sensitivities are reported. We survey the scientific goals which include the observation of neutrino-nucleus coherent scattering, the studies of neutrino magnetic moments, as well as the searches of WIMP dark matter. In particular, a threshold of 100-200 eV and a sub-keV background comparable to underground experiments were achieved with prototype detectors. New limits were set for WIMPs with mass between 3-6 GeV. The prospects of the realization of full-scale experiments are discussed.

  18. Energy Information Agency's 2003 Commercial Building Energy Consumption Survey Tables

    Broader source: Energy.gov [DOE]

    Energy use intensities in commercial buildings vary widely and depend on activity and climate, as shown in this data table, which was derived from the Energy Information Agency's 2003 Commercial Building Energy Consumption Survey.

  19. Geothermal Energy Growth Continues, Industry Survey Reports

    Broader source: Energy.gov [DOE]

    A survey released by the Geothermal Energy Association (GEA) shows continued growth in the number of new geothermal power projects under development in the United States, a 20% increase since January of this year.

  20. Constraints on the dark energy equation of state from the imprint of baryons on the power spectrum of clusters

    E-Print Network [OSTI]

    R. Angulo; C. M. Baugh; C. S. Frenk; R. G. Bower; A. Jenkins; S. L. Morris

    2005-06-13

    Acoustic oscillations in the baryon-photon fluid leave a signature in the matter power spectrum. The overall shape of the spectrum and the wavelength of the oscillations depend upon the sound horizon scale at recombination. Using the $\\Lambda$ cold dark matter Hubble Volume simulation, we show that the imprint of baryons is visible in the power spectrum of cluster-mass dark matter haloes, in spite of significant differences between the halo power spectrum and the prediction of linear perturbation theory. A measurement of the sound horizon scale can constrain the dark energy equation of state. We show that a survey of clusters at intermediate redshift ($ z\\sim1 $), like the Sunyaev-Zeldovich survey proposed by the South Pole Telescope or a red sequence photometric survey with VISTA, could potentially constrain the sound horizon scale to an accuracy of $\\sim 2%$, in turn fixing the ratio of the pressure of the dark energy to its density ($w$) to better than $\\sim 10%$. Our approach does not require knowledge of the cluster mass, unlike those that depend upon the abundance of clusters.

  1. Heal the world: Avoiding the cosmic doomsday in the holographic dark energy model

    E-Print Network [OSTI]

    Xin Zhang

    2009-12-14

    The current observational data imply that the universe would end with a cosmic doomsday in the holographic dark energy model. However, unfortunately, the big-rip singularity will ruin the theoretical foundation of the holographic dark energy scenario. To rescue the holographic scenario of dark energy, we employ the braneworld cosmology and incorporate the extra-dimension effects into the holographic theory of dark energy. We find that such a mend could erase the big-rip singularity and leads to a de Sitter finale for the holographic cosmos. Therefore, in the holographic dark energy model, the extra-dimension recipe could heal the world.

  2. New Evidence for Interacting Dark Energy from BOSS

    E-Print Network [OSTI]

    E. Abdalla; Elisa G. M. Ferreira; Jerome Quintin; Bin Wang

    2014-12-19

    In this Letter we show that an interaction between dark matter and dark energy is favored by the most recent large scale structure observations. The result presented by the BOSS-SDSS collaboration measuring the baryon acoustic oscillations of the Ly-$\\alpha$ forest from high redshift quasars indicates a $2.5\\sigma$ departure from the standard $\\Lambda$CDM model. This is the first time that the evolution of dark energy at high redshifts has been measured and the current results cannot be explained by simple generalizations of the cosmological constant. We show here that a simple phenomenological interaction in the dark sector provides a good explanation for this deviation, naturally accommodating the Hubble parameter obtained by BOSS, $H(z=2.34)=222 \\pm 7 ~\\mathrm{km~s^{-1}~Mpc^{-1}}$, for two of the proposed models with a positive coupling constant and rejecting the null interaction at more than $2\\sigma$. For this we used the adjusted values of the cosmological parameters for the interacting models from the current observational data sets. This small and positive value of the coupling constant also helps alleviate the coincidence problem.

  3. Testing coupled dark energy with large scale structure observation

    SciTech Connect (OSTI)

    Yang, Weiqiang; Xu, Lixin, E-mail: d11102004@mail.dlut.edu.cn, E-mail: lxxu@dlut.edu.cn [Institute of Theoretical Physics, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 (China)

    2014-08-01

    The coupling between the dark components provides a new approach to mitigate the coincidence problem of cosmological standard model. In this paper, dark energy is treated as a fluid with a constant equation of state, whose coupling with dark matter is Q-bar =3H?{sub x}?-bar {sub x}. In the frame of dark energy, we derive the evolution equations for the density and velocity perturbations. According to the Markov Chain Monte Carlo method, we constrain the model by currently available cosmic observations which include cosmic microwave background radiation, baryon acoustic oscillation, type Ia supernovae, and f?{sub 8}(z) data points from redshift-space distortion. The results show the interaction rate in ? regions: ?{sub x} = 0.00328{sub -0.00328-0.00328-0.00328}{sup +0.000736+0.00549+0.00816}, which means that the recently cosmic observations favor a small interaction rate which is up to the order of 10{sup -2}, meanwhile, the measurement of redshift-space distortion could rule out the large interaction rate in the ? region.

  4. Graviton Dominated Eras of Universe Evolution, Inflation and Dark Energy

    E-Print Network [OSTI]

    Leonid Marochnik

    2015-10-01

    This review represents an attempt to gather together new and published results of instanton theory of gravitons with an emphasis on their cosmological applications (inflation and dark energy). The empty space (with no matter fields) is not really empty because of natural quantum metric fluctuations, i.e. gravitons. It is shown that in the homogeneous isotropic empty Universe gravitons can be tunneled into Euclidean space of imaginary time through a topologically impenetrable barrier. They are damped there, giving their energy to the formation of the self-consistent de Sitter state, which is invariant with respect to the Wick rotation. The latter suggests that it is formed in real time too, and its appearance there can be considered as tunneling from nothing. The present Universe is already ~70% empty so that the effects associated with the emptiness of space must already be very noticeable, and they are (dark energy). The inflation most likely had to start from the vacuum state also. De Sitter accelerated expansion of the empty Universe naturally explains the origin of dark energy and inflation because at the start (inflation) and by the end (dark energy) of its evolution the Universe is empty. In distinction to scalar field theories, the CMB anisotropy of the order of 10^-5 is produced by fluctuations in the number of gravitons. The existence of a threshold and unique coincidence of topologically impenetrable barriers for tunneling takes place for the matter dominated epoch and De Sitter State only. These facts provide a solution to the coincidence problem. The theoretical prediction that the equation-of-state parameter should be w>-1 for inflation and wenergy is consistent with observational data. The mandatory use of imaginary time (and then back to real time) suggests that time could be a complex variable, and this fact has a deep but still not understood meaning

  5. On the internal consistency of holographic dark energy models

    SciTech Connect (OSTI)

    Horvat, R

    2008-10-15

    Holographic dark energy (HDE) models, underpinned by an effective quantum field theory (QFT) with a manifest UV/IR connection, have become convincing candidates for providing an explanation of the dark energy in the universe. On the other hand, the maximum number of quantum states that a conventional QFT for a box of size L is capable of describing relates to those boxes which are on the brink of experiencing a sudden collapse to a black hole. Another restriction on the underlying QFT is that the UV cut-off, which cannot be chosen independently of the IR cut-off and therefore becomes a function of time in a cosmological setting, should stay the largest energy scale even in the standard cosmological epochs preceding a dark energy dominated one. We show that, irrespective of whether one deals with the saturated form of HDE or takes a certain degree of non-saturation in the past, the above restrictions cannot be met in a radiation dominated universe, an epoch in the history of the universe which is expected to be perfectly describable within conventional QFT.

  6. Illuminating Dark Photons with High-Energy Colliders

    E-Print Network [OSTI]

    David Curtin; Rouven Essig; Stefania Gori; Jessie Shelton

    2015-02-27

    High-energy colliders offer a unique sensitivity to dark photons, the mediators of a broken dark U(1) gauge theory that kinetically mixes with the Standard Model (SM) hypercharge. Dark photons can be detected in the exotic decay of the 125 GeV Higgs boson, h -> Z Z_D -> 4l, and in Drell-Yan events, pp -> Z_D -> ll. If the dark U(1) is broken by a hidden-sector Higgs mechanism, then mixing between the dark and SM Higgs bosons also allows the exotic decay h -> Z_D Z_D -> 4l. We show that the 14 TeV LHC and a 100 TeV proton-proton collider provide powerful probes of both exotic Higgs decay channels. In the case of kinetic mixing alone, direct Drell-Yan production offers the best sensitivity to Z_D, and can probe epsilon >~ 9 x 10^(-4) (4 x 10^(-4)) at the HL-LHC (100 TeV pp collider). The exotic Higgs decay h -> Z Z_D offers slightly weaker sensitivity, but both measurements are necessary to distinguish the kinetically mixed dark photon from other scenarios. If Higgs mixing is also present, then the decay h -> Z_D Z_D can allow sensitivity to the Z_D for epsilon >~ 10^(-9) - 10^(-6) (10^(-10) - 10^(-7)) for the mass range 2 m_mu < m_(Z_D) < m_h/2 by searching for displaced dark photon decays. We also compare the Z_D sensitivity at pp colliders to the indirect, but model-independent, sensitivity of global fits to electroweak precision observables. We perform a global electroweak fit of the dark photon model, substantially updating previous work in the literature. Electroweak precision measurements at LEP, Tevatron, and the LHC exclude epsilon as low as 3 x 10^(-2). Sensitivity can be improved by up to a factor of ~2 with HL-LHC data, and an additional factor of ~4 with ILC/GigaZ data.

  7. Einstein-Aether Theory as an Alternative to Dark Energy Model?

    E-Print Network [OSTI]

    Meng, Xin-He

    2011-01-01

    In the Einstein-aether theory by taking a special form of the ${\\cal F}({\\cal K})$ (a free function in this theory) the possibility of Einstein-aether theory as an alternative to dark energy model is discussed in details, that is, taking a special Aether field as a dark energy candidate. We compute the joint statistic constraints on this special model's parameters by using the recent type Ia supernovae (SNe Ia) data, the Cosmic Microwave Background (CMB) shift parameter data, and the Baryonic Acoustic Oscillations (BAOs) data traced by the Sloan Digital Sky Survey (SDSS). Furthermore, we analyze other constrains from the observational Hubble parameter data (OHD). The comparison with the standard cosmological model (cosmological constant $\\Lambda$ Cold Dark Matter ($\\Lambda$CDM) model) is clearly shown with new features; also we discuss an interesting relation between the coupling constant M in this model and the possible existence of a special accelerate scale in the MOdified Newtonian Dynamics (MOND) model i...

  8. The value of the equation of state of dark energy

    E-Print Network [OSTI]

    Raul Jimenez

    2003-05-20

    From recent CMB and Large Scale Structure observations the value of the equation of state of dark energy, assuming it to be constant in time, is constrained to be -1.3dark energy being a classical vacuum term. Here we describe two novel and independent methods, sensitive to different systematics, that give the same value for w and similar confidence regions. This suggests that systematics are not an issue in current determinations of w. The first method yields a measurement of $w$ that relies on the minimum number of model-dependent parameters; the second method is a non-parametric measurement of the time dependence of w(z). We also present a method to statistically determine the edge of a distribution.

  9. Possible Measurable Effects of Dark Energy in Rotating Superconductors

    E-Print Network [OSTI]

    Clovis Jacinto de Matos; Christian Beck

    2007-07-12

    We discuss recent laboratory experiments with rotating superconductors and show that three so far unexplained experimentally observed effects (anomalous acceleration signals, anomalous gyroscope signals, Cooper pair mass excess) can be physically explained in terms of a possible interaction of dark energy with Cooper pairs. Our approach is based on a Ginzburg-Landau-like model of electromagnetic dark energy, where gravitationally active photons obtain mass in the superconductor. We show that this model can account simultaneously for the anomalous acceleration and anomalous gravitomagnetic fields around rotating superconductors measured by Tajmar et al. and for the anomalous Cooper pair mass in superconductive Niobium, measured by Cabrera and Tate. It is argued that these three different physical effects are ultimately different experimental manifestations of the simultaneous spontaneous breaking of gauge invariance, and of the principle of general covariance in superconductive materials.

  10. Dark Energy and the Return of the Phoenix Universe

    E-Print Network [OSTI]

    Jean-Luc Lehners; Paul J. Steinhardt

    2008-12-17

    In cyclic universe models based on a single scalar field (e.g., the radion determining the distance between branes in M-theory), virtually the entire universe makes it through the ekpyrotic smoothing and flattening phase, bounces, and enters a new epoch of expansion and cooling. This stable evolution cannot occur, however, if scale-invariant curvature perturbations are produced by the entropic mechanism because it requires two scalar fields (e.g., the radion and the Calabi-Yau dilaton) evolving along an unstable classical trajectory. In fact, we show here that an overwhelming fraction of the universe fails to make it through the ekpyrotic phase; nevertheless, a sufficient volume survives and cycling continues forever provided the dark energy phase of the cycle lasts long enough, of order a trillion years. Two consequences are a new role for dark energy and a global structure of the universe radically different from that of eternal inflation.

  11. f(R) as a dark energy fluid

    E-Print Network [OSTI]

    R. A. Battye; B. Bolliet; J. A. Pearson

    2015-08-19

    We study the equations for the evolution of cosmological perturbations in $f\\left(\\mathcal{R}\\right)$ and conclude that this modified gravity model can be expressed as a dark energy fluid at background and linearised perturbation order. By eliminating the extra scalar degree of freedom known to be present in such theories, we are able to characterise the evolution of the perturbations in the scalar sector in terms of equations of state for the entropy perturbation and anisotropic stress which are written in terms of the density and velocity perturbations of the dark energy fluid and those in the matter, or the metric perturbations. We also do the same in the much simpler vector and tensor sectors. In order to illustrate the simplicity of this formulation, we numerically evolve perturbations in a small number of cases.

  12. f(R) as a dark energy fluid

    E-Print Network [OSTI]

    Battye, R A; Pearson, J A

    2015-01-01

    We study the equations for the evolution of cosmological perturbations in $f\\left(\\mathcal{R}\\right)$ and conclude that this modified gravity model can be expressed as a dark energy fluid at background and linearised perturbation order. By eliminating the extra scalar degree of freedom known to be present in such theories, we are able to characterise the evolution of the perturbations in the scalar sector in terms of equations of state for the entropy perturbation and anisotropic stress which are written in terms of the density and velocity perturbations of the dark energy fluid and those in the matter, or the metric perturbations. We also do the same in the much simpler vector and tensor sectors. In order to illustrate the simplicity of this formulation, we numerically evolve perturbations in a small number of cases.

  13. The State of the Dark Energy Equation of State

    E-Print Network [OSTI]

    Alessandro Melchiorri; Laura Mersini; Carolina J. Odman; Mark Trodden

    2003-04-16

    By combining data from seven cosmic microwave background experiments (including the latest WMAP results) with large scale structure data, the Hubble parameter measurement from the Hubble Space Telescope and luminosity measurements of Type Ia supernovae we demonstrate the bounds on the dark energy equation of state $w_Q$ to be $-1.38< w_Q <-0.82$ at the 95% confidence level. Although our limit on $w_Q$ is improved with respect to previous analyses, cosmological data does not rule out the possibility that the equation of state parameter $w_Q$ of the dark energy $Q$ is less than -1. We present a tracking model that ensures $w_Q \\le -1$ at recent times and discuss the observational consequences.

  14. Holography, Dark Energy and Entropy of Large Cosmic Structures

    E-Print Network [OSTI]

    C. Sivaram; Kenath Arun

    2013-03-15

    As is well known, black hole entropy is proportional to the area of the horizon suggesting a holographic principle wherein all degrees of freedom contributing to the entropy reside on the surface. In this note, we point out that large scale dark energy (such as a cosmological constant) constraining cosmic structures can imply a similar situation for the entropy of a hierarchy of such objects.

  15. Cosmological Bardeen-Cooper-Schrieffer condensate as dark energy

    E-Print Network [OSTI]

    Stephon Alexander; Tirthabir Biswas; Gianluca Calcagni

    2010-03-29

    We argue that the occurrence of late-time acceleration can conveniently be described by first-order general relativity covariantly coupled to fermions. Dark energy arises as a Bardeen-Cooper-Schrieffer condensate of fermions which forms in the early universe. At late times, the gap and chemical potential evolve to have an equation of state with effective negative pressure, thus naturally leading to acceleration.

  16. Constraining dark energy through the stability of cosmic structures

    SciTech Connect (OSTI)

    Pavlidou, V.; Tetradis, N.; Tomaras, T.N. E-mail: ntetrad@phys.uoa.gr

    2014-05-01

    For a general dark-energy equation of state, we estimate the maximum possible radius of massive structures that are not destabilized by the acceleration of the cosmological expansion. A comparison with known stable structures constrains the equation of state. The robustness of the constraint can be enhanced through the accumulation of additional astrophysical data and a better understanding of the dynamics of bound cosmic structures.

  17. Solar System Constraints on Gauss-Bonnet Dark Energy

    E-Print Network [OSTI]

    Stephen C. Davis

    2007-08-15

    Quadratic curvature Gauss-Bonnet gravity may be the solution to the dark energy problem, but a large coupling strength is required. This can lead to conflict with laboratory and planetary tests of Newton's law, as well as light bending. The corresponding constraints are derived. If applied directly to cosmological scales, the resulting bound on the density fraction is |Omega_GB| < 3.6 x 10^-32.

  18. Avoiding the dark energy coincidence problem with a cosmic vector

    E-Print Network [OSTI]

    Jose Beltran Jimenez; Antonio L. Maroto

    2008-12-10

    We show that vector theories on cosmological scales are excellent candidates for dark energy. We consider two different examples, both are theories with no dimensional parameters nor potential terms, with natural initial conditions in the early universe and the same number of free parameters as LCDM. The first one exhibits scaling behaviour during radiation and a strong phantom phase today, ending in a "big-freeze" singularity. This model provides the best fit to date for the SNIa Gold dataset. The second theory we consider is standard electromagnetism. We show that a temporal electromagnetic field on cosmological scales generates an effective cosmological constant and that primordial electromagnetic quantum fluctuations produced during electroweak scale inflation could naturally explain, not only the presence of this field, but also the measured value of the dark energy density. The theory is compatible with all the local gravity tests, and is free from classical or quantum instabilities. Thus, not only the true nature of dark energy could be established without resorting to new physics, but also the value of the cosmological constant would find a natural explanation in the context of standard inflationary cosmology.

  19. The Energy Density of the Quaternionic Field as Dark Energy in the Universe

    E-Print Network [OSTI]

    V. Majernik

    2003-11-06

    In this article we describe a model of the universe consisting of a mixture of the ordinary matter and a so-called cosmic quaternionic field. The basic idea here consists in an attempt to interpret $\\Lambda$ as the energy density of the quaternionic field whose source is any form of energy including the proper energy density of this field. We set the energy density of this field to $\\Lambda$ and show that the ratio of ordinary dark matter energy density assigned to $\\Lambda$ is constant during the cosmic evolution. We investigate the interaction of the quaternionic field with the ordinary dark matter and show that this field exerts a force on the moving dark matter which might possible create the dark matter in the early universe. Such determined $\\Lambda$ fulfils the requirements asked from the dark energy. In this model of the universe, the cosmical constant, the fine-tuning and the age problems might be solved. Finally, we sketch the evolution of the universe with the cosmic quaternionic field and show that the energy density of the cosmic quaternionic field might be a possible candidate for the dark energy.

  20. A Dark Energy Model in Lyra Manifold

    E-Print Network [OSTI]

    Hoavo Hova

    2012-04-11

    We consider, in normal-gauge Lyra's geometry, evolution of a homogeneous isotropic universe in a gravitational model involving only the standard matter in interaction with a displacement vector field $\\phi_{\\mu}$. Considering both constant and time-dependent displacement vector field we show that the observed cosmic acceleration could be explained without considering an alien energy component with a negative pressure.

  1. A Dark Energy Model in Lyra Manifold

    E-Print Network [OSTI]

    Hova, Hoavo

    2012-01-01

    We consider, in normal-gauge Lyra's geometry, evolution of a homogeneous isotropic universe in a gravitational model involving only the standard matter in interaction with a displacement vector field $\\phi_{\\mu}$. Considering both constant and time-dependent displacement vector field we show that the observed cosmic acceleration could be explained without considering an alien energy component with a negative pressure.

  2. Dark Energy and Dark Matter From Hidden Symmetry of Gravity Model with a Non-Riemannian Volume Form

    E-Print Network [OSTI]

    Guendelman, Eduardo; Pacheva, Svetlana

    2015-01-01

    We show that dark energy and dark matter can be described simultaneously by ordinary Einstein gravity interacting with a single scalar field provided the scalar field Lagrangian couples in a symmetric fashion to two different spacetime volume-forms (covariant integration measure densities) on the spacetime manifold - one standard Riemannian given by the square-root of the determinant of the pertinent Riemannian metric and another non-Riemannian volume-form independent of the Riemannian metric, defined in terms of an auxiliary antisymmetric tensor gauge field of maximal rank. Integration of the equations of motion of the latter auxiliary gauge field produce an a priori arbitrary integration constant that plays the role of a dynamically generated cosmological constant or dark energy. Moreover, the above modified scalar field action turns out to possess a hidden Noether symmetry whose associated conserved current describes a pressureless "dust" fluid which we can identify with the dark matter completely decouple...

  3. Dark Energy Generated by Warped Cosmic Strings

    E-Print Network [OSTI]

    Reinoud Jan Slagter

    2014-07-29

    If we live on the weak brane in a warped 5D bulk spacetime, gravitational waves and brane fluctuations can be generated by a part of the 5D Weyl tensor and carries information of the gravitational field outside the brane. We consider the U(1) self-gravitating scalar-gauge field on the warped spacetime without bulk matter. It turns out that "branons" can be formed dynamically, due to the modified energy-momentum tensor components of the cosmic string. It turns out that the parameter $\\alpha$, i.e., the gauge-to-scalar mass, changes from a value $>1$ to a value $wave energy. It is the time-dependent part of the warp factor which triggers this extraordinary behavior.

  4. New Horizons in Gravity: Dark Energy and Condensate Stars

    E-Print Network [OSTI]

    Emil Mottola

    2011-07-25

    Black holes are an apparently unavoidable prediction of classical General Relativity, at least if matter obeys the strong energy condition rho + 3p > 0. However quantum vacuum fluctuations generally violate this condition, as does the eq. of state of cosmological dark energy. When quantum effects are considered, black holes lead to a number of thermodynamic paradoxes associated with the Hawking temperature and assumption of black hole entropy, which are briefly reviewed. It is argued that the largest quantum effects arise from the conformal scalar degrees of freedom generated by the trace anomaly of the stress-energy tensor in curved space. At event horizons these can have macroscopically large backreaction effects on the geometry, potentially removing the classical event horizon of black hole and cosmological spacetimes, replacing them with a quantum phase boundary layer, where the effective value of the gravitational vacuum energy density can change. In the effective theory including the quantum effects of the anomaly, the cosmological term becomes a dynamical condensate, whose value depends upon boundary conditions at the horizon. By taking a positive value in the interior of a fully collapsed star, the effective cosmological term removes any singularity, replacing it with a smooth dark energy de Sitter interior. The resulting gravitational vacuum condensate star (or gravastar) configuration resolves all black hole paradoxes, and provides a testable alternative to black holes as the final quantum mechanical end state of complete gravitational collapse. The observed dark energy of our universe likewise may be a macroscopic finite size effect whose value depends not on Planck scale or other microphysics but on the cosmological Hubble horizon scale itself.

  5. Tracking Dark Energy from Axion-Gauge Field Couplings

    E-Print Network [OSTI]

    Alexander, Stephon; Froehlich, Juerg

    2016-01-01

    We propose a model of Dark Energy in which the field currently dominating the energy density of the universe is an "axion field" linearly coupled to the Pontryagin density, $ \\text{tr}(F \\wedge F)$, (i.e., the exterior derivative of the Chern-Simons form) of a massive gauge field. We assume that the axion has self-interactions corresponding to a non-trivial (exponential) potential. We argue that a non-vanishing magnetic helicity of the gauge field triggers slow-rolling of the axion at field values far below the Planck scale. Our proposal leads to a "Tracking Dark Energy Scenario" in which the contribution of the axion energy density to the total energy density is constant (and small) during the early radiation phase, until a secular growth term proportional to the Pontryagin density of the gauge field becomes dominant. The initially small contribution of the axion field to the total energy density is related to the observed small baryon-to-entropy ratio. Some speculations concerning the nature of the gauge fi...

  6. Telluric Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmental Jump to:EA EISTJ Automation Jump to:Information 8) JumpTellurianTelluric Survey

  7. Introduction to Modified Gravity and Gravitational Alternative for Dark Energy

    E-Print Network [OSTI]

    Nojiri, S

    2006-01-01

    We review various modified gravities considered as gravitational alternative for dark energy. Specifically, we consider the versions of $f(R)$, $f(G)$ or $f(R,G)$ gravity, model with non-linear gravitational coupling or string-inspired model with Gauss-Bonnet-dilaton coupling in the late universe where they lead to cosmic speed-up. It is shown that some of such theories may pass the Solar System tests. On the same time, it is demonstrated that they have quite rich cosmological structure: they may naturally describe the effective (cosmological constant, quintessence or phantom) late-time era with a possible transition from decceleration to acceleration thanks to gravitational terms which increase with scalar curvature decrease. The possibility to explain the coincidence problem as the manifestation of the universe expansion in such models is mentioned. The late (phantom or quintessence) universe filled with dark fluid with inhomogeneous equation of state (where inhomogeneous terms are originated from the modif...

  8. Existence of Negative Gravity Material Identification of Dark Energy Dark Matter Isothermal Gravitational Equilibrium and Galactic Rotation Theory

    E-Print Network [OSTI]

    James G. Gilson

    2012-06-23

    A solution to Einstein's field equations via the Friedman equations is shown to produce a cosmological model that is in exact agreement with the measurements made by the dark energy astronomers. All the essential physical parameters are obtained as epoch dependent functions all in closed form. The equations of state are obtained for total density, non-dark energy density and dark energy density. An interpretation of the structure involving a dark energy mass distribution that is twice the usual value is shown to clarify greatly the physical significance of the mathematics. It is asserted that the astronomer's measurements together with the mathematical model proves that the universe is permeated uniformly with a positive mass density that caries a negative gravitational constant, -G, characteristic. This mass component is identified with the dark energy content of the universe that has been postulated to explain the observed acceleration. Another result implied by the model is that there is twice the amount of dark energy that is usually considered to be present. This last point is analysed in more detail in appendix 1 using Einstein's field equations. Five additional appendices, 2, 3, 4, 5 and 6 in which isothermal gravitational dark matter equilibrium and the galactic rotations curve flatness problem are examined in detail. Appendix 5 is concerned with mass clumping and expressing gravitational isothermal equilibrium constraints using a cosmological Schr\\"odinger equation to demonstrate the existence of a new quantum force involved with galactic stability. Appendix 6 is concerned with gravitational quantization. Each appendix has its own abstract.

  9. On Einstein - Weyl unified model of dark energy and dark matter

    E-Print Network [OSTI]

    A. T. Filippov

    2009-05-29

    Here I give a more detailed account of the part of the conference report that was devoted to reinterpreting the Einstein `unified models of gravity and electromagnetism' (1923) as the unified theory of dark energy (cosmological constant) and dark matter (neutral massive vector particle having only gravitational interactions). After summarizing Einstein's work and related earlier work of Weyl and Eddington, I present an approach to finding spherically symmetric solutions of the simplest variant of the Einstein models that was earlier mentioned in Weyl's work as an example of his generalization of general relativity. The spherically symmetric static solutions and homogeneous cosmological models are considered in some detail. As the theory is not integrable we study approximate solutions. In the static case, we show that there may exist two horizons and derive solutions near horizons. In cosmology, we propose to study the corresponding expansions of possible solutions near the origin and derive these expansions in a simplified model neglecting anisotropy. The structure of the solutions seems to hint at a possibility of an inflation mechanism that does not require adding scalar fields.

  10. Coincidences of Dark Energy with Dark Matter -- Clues for a Simple Alternative?

    E-Print Network [OSTI]

    HongSheng Zhao

    2007-10-21

    A rare coincidence of scales in standard particle physics is needed to explain why $\\Lambda$ or the negative pressure of cosmological dark energy (DE) coincides with the positive pressure $P_0$ of random motion of dark matter (DM) in bright galaxies. Recently Zlosnik et al. (2007) propose to modify the Einsteinian curvature by adding a non-linear pressure from a medium flowing with a four-velocity vector field $U^\\mu$. We propose to check whether a smooth extension of GR with a simple kinetic Lagrangian of $U^\\mu$ can be constructed, and whether the pressure can bend space-time sufficiently to replace the roles of a $w=-1$ DE, $w=0$ Cold DM and heavy neutrinos in explaining anomalous accelerations at all scales. As a specific proof of concept we find a Vector-for-$\\Lambda$ model (${\\mathbf V\\Lambda}$-model) and its variants. With essentially {\\it no free parameters}, these appear broadly consistent with the solar system, gravitational potentials in dwarf spiral galaxies and the bullet cluster of galaxies, early universe with inflation, structure formation and BBN, and late acceleration with a 1:3 ratio of DM:DE.

  11. Coincidences of Dark Energy with Dark Matter -- Clues for a Simple Alternative?

    E-Print Network [OSTI]

    Zhao, HongSheng

    2007-01-01

    A rare coincidence of scales in standard particle physics is needed to explain why $\\Lambda$ or the negative pressure of cosmological dark energy (DE) coincides with the positive pressure $P_0$ of random motion of dark matter (DM) in bright galaxies. Recently Zlosnik et al. (2007) propose to modify the Einsteinian curvature by adding a non-linear pressure from a medium flowing with a four-velocity vector field $U^\\mu$. We propose to check whether a smooth extension of GR with a simple kinetic Lagrangian of $U^\\mu$ can be constructed, and whether the pressure can bend space-time sufficiently to replace the roles of a $w=-1$ DE, $w=0$ Cold DM and heavy neutrinos in explaining anomalous accelerations at all scales. As a specific proof of concept we find a Vector-for-$\\Lambda$ model (${\\mathbf V\\Lambda}$-model) and its variants. With essentially {\\it no free parameters}, these appear broadly consistent with the solar system, gravitational potentials in dwarf spiral galaxies and the bullet cluster of galaxies, ear...

  12. A Terrestrial Search for Dark Contents of the Vacuum, Such as Dark Energy, Using Atom Interferometry

    SciTech Connect (OSTI)

    Adler, Ronald J.; Muller, Holger; Perl, Martin L.; /KIPAC, Menlo Park /SLAC

    2012-06-11

    We describe the theory and first experimental work on our concept for searching on earth for the presence of dark contents of the vacuum (DCV) using atom interferometry. Specifically, we have in mind any DCV that has not yet been detected on a laboratory scale, but which might manifest itself as dark energy on the cosmological scale. The experimental method uses two atom interferometers to cancel the effect of earth's gravity and diverse noise sources. It depends upon two assumptions: first, that the DCV possesses some space inhomogeneity in density, and second that it exerts a sufficiently strong nongravitational force on matter. The motion of the apparatus through the DCV should then lead to an irregular variation in the detected matter-wave phase shift. We discuss the nature of this signal and note the problem of distinguishing it from instrumental noise. We also discuss the relation of our experiment to what might be learned by studying the noise in gravitational wave detectors such as LIGO. The paper concludes with a projection that a future search of this nature might be carried out using an atom interferometer in an orbiting satellite. The laboratory apparatus is now being constructed.

  13. Dark Energy: A Missing Physical Ingredient

    E-Print Network [OSTI]

    Wanas, M I

    2008-01-01

    Recent observation of supernovae type Ia show clearly that there is a large scale repulsive force in the Universe. Neither of the four known fundamental interactions can account for this repulsive force. Gravity is known to be the interaction responsible for the large scale structure and evolution of the Universe. The problem with gravity is that it gives rise to a force which is attractive only. Gravity theories, including General Relativity, deals with gravity as an attractive force. Although this is consistent with our experience in the solar system and other similar astrophysical systems, gravity theories fail to account for SN type Ia observation. So, we are in a real problem concerning the interpretation of these observation. This problem is only ten years old. In order to go out of this problematic situation, scientists have suggested the existence of a type of energy in the Universe that is responsible for the above mentioned repulsive force. They have given this type of energy the exotic term {\\it "D...

  14. A topological origin for Dark Energy

    E-Print Network [OSTI]

    Espiro, J Lorca

    2015-01-01

    Cosmology struggles with the theoretical problems generated by the observed value and recent emergence of a cosmological constant, in the standard model of cosmology, i.e. the concordance model. We propose to provide a more natural explanation for its value than the conventional quantum vacuum energy in the guise of topological invariants. Introducing topological classes densities as Lagrange multipliers, an effective cosmological constant is generated. General Relativity is reestablished by cancelling the torsion thus generated, which provides constraints on the invariants and yield the form of the effective cosmological constant. As it is divided by the total volume of spacetime, its small value compared to the Planck scale is therefore natural. It also provides a direct measurement of the global Euler number.

  15. Trending and Tracking Energy Survey 

    E-Print Network [OSTI]

    Nipper, J.

    2015-01-01

    of the Thrity-Seventh Industrial Energy Technology Conference New Orleans, LA. June 2-4, 2015 ? Privately Owned and Operated since 1998 ? Clients in North America, Europe and Asia ? Excellent Safety Record – Perfect OSHA rating ? Experience – More Than 60... Years in the Industry ESL-IE-15-06-33 Proceedings of the Thrity-Seventh Industrial Energy Technology Conference New Orleans, LA. June 2-4, 2015 Petro Chemical Energy's services have saved our clients annually, including: • 3M • Akzo Nobel • American...

  16. Testing the Dark-Energy-Dominated Cosmology by the Solar-System Experiments

    E-Print Network [OSTI]

    Yurii V. Dumin

    2008-08-08

    According to the recent astronomical data, the most part of energy in the Universe is in the 'dark' form, which is effectively described by Lambda-term in Einstein equations. All arguments in favor of the dark energy were obtained so far from the observational data related to very large (intergalactic) scales. Is it possible to find a manifestation of the dark energy at much less scales (e.g. inside the Solar system)?

  17. Cosmic inflation, deceleration, acceleration, dark matter, and dark 'energy' in one coherent package

    E-Print Network [OSTI]

    Homer G. Ellis

    2015-03-15

    In creating his gravitational field equations Einstein assumed without justification that inertial mass, even in its equivalent form as energy, is a source of gravity. Giving up that assumption allows modifying the field equations to a form in which a positive cosmological constant is seen to (mis)represent a uniform negative net mass density of gravitationally attractive and gravitationally repulsive matter. Field equations with both positive and negative active gravitational mass densities of both primordial and continuously created matter incorporated, along with two scalar fields to 'relax the constraints' on the space-time geometry, yield cosmological solutions that exhibit inflation, deceleration, coasting, acceleration, and a 'big bounce' instead of a 'big bang', and provide good fits to a Hubble diagram of type Ia supernovae data. The repulsive matter is identified as the back sides of the 'drainholes' introduced by the author in 1973 as solutions of those same field equations. Drainholes are topological tunnels in space which gravitationally attract on their front, entrance sides and repel more strongly on their back, exit sides. The front sides serve both as the gravitating cores of the visible, baryonic particles of primordial matter and as the continuously created, invisible particles of the 'dark matter' needed to hold together the large scale structures seen in the universe; the back sides serve as the misnamed 'dark energy' driving the current acceleration of the expansion of the universe. Formation of cosmic voids, walls, filaments, and nodes is attributed to expulsion of drainhole entrances from regions populated by drainhole exits, and accumulation of the entrances on boundaries separating those regions.

  18. Cosmic acceleration without dark energy: background tests and thermodynamic analysis

    SciTech Connect (OSTI)

    Lima, J.A.S.; Graef, L.L.; Pavón, D.; Basilakos, Spyros E-mail: leilagraef@usp.br E-mail: svasil@academyofathens.gr

    2014-10-01

    A cosmic scenario with gravitationally induced particle creation is proposed. In this model the Universe evolves from an early to a late time de Sitter era, with the recent accelerating phase driven only by the negative creation pressure associated with the cold dark matter component. The model can be interpreted as an attempt to reduce the so-called cosmic sector (dark matter plus dark energy) and relate the two cosmic accelerating phases (early and late time de Sitter expansions). A detailed thermodynamic analysis including possible quantum corrections is also carried out. For a very wide range of the free parameters, it is found that the model presents the expected behavior of an ordinary macroscopic system in the sense that it approaches thermodynamic equilibrium in the long run (i.e., as it nears the second de Sitter phase). Moreover, an upper bound is found for the Gibbons–Hawking temperature of the primordial de Sitter phase. Finally, when confronted with the recent observational data, the current 'quasi'-de Sitter era, as predicted by the model, is seen to pass very comfortably the cosmic background tests.

  19. Sudden Future Singularity models as an alternative to Dark Energy?

    E-Print Network [OSTI]

    Hoda Ghodsi; Martin A. Hendry; Mariusz P. Dabrowski; Tomasz Denkiewicz

    2011-03-11

    Current observational evidence does not yet exclude the possibility that dark energy could be in the form of phantom energy. A universe consisting of a phantom constituent will be driven toward a drastic end known as the `Big Rip' singularity where all the matter in the universe will be destroyed. Motivated by this possibility, other evolutionary scenarios have been explored by Barrow, including the phenomena which he called Sudden Future Singularities (SFS). In such a model it is possible to have a blow up of the pressure occurring at sometime in the future evolution of the universe while the energy density would remain unaffected. The particular evolution of the scale factor of the universe in this model that results in a singular behaviour of the pressure also admits acceleration in the current era. In this paper we will present the results of our confrontation of one example class of SFS models with the available cosmological data from high redshift supernovae, baryon acoustic oscillations (BAO) and the cosmic microwave background (CMB). We then discuss the viability of the model in question as an alternative to dark energy.

  20. Dark Energy Models and Laws of Thermodynamics in Bianchi I Model

    E-Print Network [OSTI]

    M. Sharif; Rabia Saleem

    2013-02-20

    This paper is devoted to check validity of the laws of thermodynamics for LRS Bianchi type I universe model which is filled with combination of dark matter and dark energy. We take two types of dark energy models, i.e., generalized holographic dark energy and generalized Ricci dark energy. It is proved that the first and generalized second law of thermodynamics are valid on the apparent horizon for both the models. Further, we take fixed radius $L$ of the apparent horizon with original holographic or Ricci dark energy. We conclude that the first and generalized second laws of thermodynamics do not hold on the horizon of fixed radius $L$ for both the models.

  1. Survey of Energy Use in Grocery Stores 

    E-Print Network [OSTI]

    Cox, R. L.; Haberl, J. S.; Claridge, D. E.

    1992-01-01

    This paper presents the results of an energy use survey assembled for 93 grocery stores in south Texas. All stores were of the same chain. Several conclusions were drawn. Total electricity consumption per square foot is roughly 9 W/ft^2 for all...

  2. Interacting polytropic gas model of phantom dark energy in non-flat universe

    E-Print Network [OSTI]

    K. Karami; S. Ghaffari; J. Fehri

    2009-11-25

    By introducing the polytropic gas model of interacting dark energy, we obtain the equation of state for the polytropic gas energy density in a non-flat universe. We show that for even polytropic index by choosing $K>Ba^{\\frac{3}{n}}$, one can obtain $\\omega^{\\rm eff}_{\\Lambda}universe dominated by phantom dark energy.

  3. Can Massive Gravitons be an Alternative to Dark Energy?

    E-Print Network [OSTI]

    Marcio E. S. Alves; Oswaldo D. Miranda; Jose C. N. de Araujo

    2010-08-24

    In this work, we explore some cosmological implications of the model proposed by M. Visser in 1998. In his approach, Visser intends to take in account mass for the graviton by means of an additional bimetric tensor in the Einstein's field equations. Our study has shown that a consistent cosmological model arises from Visser's approach. The most interesting feature is that an accelerated expansion phase naturally emerges from the cosmological model, and we do not need to postulate any kind of dark energy to explain the current observational data for distant type Ia supernovae (SNIa).

  4. Modified GBIG Scenario as a Successful Alternative for Dark Energy

    E-Print Network [OSTI]

    Nozari, Kourosh

    2009-01-01

    We construct a DGP-inspired braneworld model where induced gravity on the brane is modified in the spirit of $f(R)$ gravity and stringy effects are taken into account by incorporation of the Gauss-Bonnet term in the bulk action. We explore cosmological dynamics of this model and we show that this scenario is a successful alternative for dark energy proposal. Interestingly, it realizes the phantom-like behavior without introduction of any phantom field on the brane and the effective equation of state parameter crosses the cosmological constant line naturally in the same way as observational data suggest.

  5. Can Massive Gravitons be an Alternative to Dark Energy?

    E-Print Network [OSTI]

    Alves, Marcio E S; de Araujo, Jose C N

    2009-01-01

    In this work, we explore some cosmological implications of the model proposed by M. Visser in 1998. In his approach, Visser intends to take in account mass for the graviton by means of an additional bimetric tensor in the Einstein's field equations. Our study has shown that a consistent cosmological model arises from Visser's approach. The most interesting feature is that an accelerated expansion phase naturally emerges from the cosmological model, and we do not need to postulate any kind of dark energy to explain the current observational data for distant type Ia supernovae (SNIa).

  6. Non-Perturbative Yang-Mills Condensate as Dark Energy

    E-Print Network [OSTI]

    Donà, Pietro; Zhang, Yang; Antolini, Claudia

    2015-01-01

    Models based on Yang-Mills condensate (YMC) have been advocated in the literature and claimed to be successful candidates to explain dark energy. Several instantiations of this simple idea have been considered, the most promising of which are reviewed here. Nevertheless, results previously attained heavily relied on the perturbative approach to the analysis of the effective Yang-Mills action, which is only adequate in the asymptotically-free limit, and were extended into a regime, the infrared limit, in which confinement is expected. We show that if a minimum of the effective Lagrangian in $\\theta \\!=\\! - F_{\\, \\, \\mu \

  7. Large-scale cosmic flows and moving dark energy

    E-Print Network [OSTI]

    Jose Beltran Jimenez; Antonio L. Maroto

    2009-02-24

    Large-scale matter bulk flows with respect to the cosmic microwave background have very recently been detected on scales 100 Mpc/h and 300 Mpc/h by using two different techniques showing an excellent agreement in the motion direction. However, the unexpectedly large measured amplitudes are difficult to understand within the context of standard LCDM cosmology. In this work we show that the existence of such a flow could be signaling the presence of moving dark energy at the time when photons decoupled from matter. We also comment on the relation between the direction of the CMB dipole and the preferred axis observed in the quadrupole in this scenario.

  8. Non-Perturbative Yang-Mills Condensate as Dark Energy

    E-Print Network [OSTI]

    Pietro Donà; Antonino Marcianò; Yang Zhang; Claudia Antolini

    2015-09-19

    Models based on Yang-Mills condensate (YMC) have been advocated in the literature and claimed to be successful candidates to explain dark energy. Several instantiations of this simple idea have been considered, the most promising of which are reviewed here. Nevertheless, results previously attained heavily relied on the perturbative approach to the analysis of the effective Yang-Mills action, which is only adequate in the asymptotically-free limit, and were extended into a regime, the infrared limit, in which confinement is expected. We show that if a minimum of the effective Lagrangian in $\\theta \\!=\\! - F_{\\, \\, \\mu \

  9. Attaining the Photometric Precision Required by Future Dark Energy Projects

    SciTech Connect (OSTI)

    Stubbs, Christopher

    2013-01-21

    This report outlines our progress towards achieving the high-precision astronomical measurements needed to derive improved constraints on the nature of the Dark Energy. Our approach to obtaining higher precision flux measurements has two basic components: 1) determination of the optical transmission of the atmosphere, and 2) mapping out the instrumental photon sensitivity function vs. wavelength, calibrated by referencing the measurements to the known sensitivity curve of a high precision silicon photodiode, and 3) using the self-consistency of the spectrum of stars to achieve precise color calibrations.

  10. Modified GBIG Scenario as an Alternative for Dark Energy

    E-Print Network [OSTI]

    Kourosh Nozari; Narges Rashidi

    2009-09-02

    We construct a DGP-inspired braneworld model where induced gravity on the brane is modified in the spirit of $f(R)$ gravity and stringy effects are taken into account by incorporation of the Gauss-Bonnet term in the bulk action. We explore cosmological dynamics of this model and we show that this scenario is a successful alternative for dark energy proposal. Interestingly, it realizes the phantom-like behavior without introduction of any phantom field on the brane and the effective equation of state parameter crosses the cosmological constant line naturally in the same way as observational data suggest.

  11. Computing model independent perturbations in dark energy and modified gravity

    SciTech Connect (OSTI)

    Battye, Richard A. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Pearson, Jonathan A., E-mail: richard.battye@manchester.ac.uk, E-mail: jonathan.pearson@durham.ac.uk [Department of Mathematical Sciences, Durham University, South Road, Durham, DH1 3LE (United Kingdom)

    2014-03-01

    We present a methodology for computing model independent perturbations in dark energy and modified gravity. This is done from the Lagrangian for perturbations, by showing how field content, symmetries, and physical principles are often sufficient ingredients for closing the set of perturbed fluid equations. The fluid equations close once ''equations of state for perturbations'' are identified: these are linear combinations of fluid and metric perturbations which construct gauge invariant entropy and anisotropic stress perturbations for broad classes of theories. Our main results are the proof of the equation of state for perturbations presented in a previous paper, and the development of the required calculational tools.

  12. The power-law expansion universe and dark energy evolution

    E-Print Network [OSTI]

    Yi-Huan Wei

    2005-02-03

    In order to depict the transition from deceleration to acceleration expansion of the universe we use a power-law expansion scale factor, $a\\sim t^{n_0+bt^m}$, with $n_0$, $b$ and $m$ three parameters determined by $H_0$, $q_0$ and $z_T$. For the spatially flat, isotropic and homogeneous universe, such a scale factor leads to the results that the dark energy density is slowly changing currently, and predicts the equation of state $w_X$ changes from $w_X>-1$ to $w_X<-1$.

  13. IRT Surveys | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History View NewTexas: Energy Resources JumpNewTexas:HydrothermallyIFB Agro Industries

  14. The Dark Energy Equation of State using Alternative High-z Cosmic Tracers

    E-Print Network [OSTI]

    M. Plionis; R. Terlevich; S. Basilakos; F. Bresolin; E. Terlevich; J. Melnick; R. Chavez

    2010-01-18

    We propose to use alternative cosmic tracers to measure the dark energy equation of state and the matter content of the Universe [w(z) & Omega_m]. Our proposed method consists of two components: (a) tracing the Hubble relation using HII galaxies which can be detected up to very large redshifts, z~4, as an alternative to supernovae type Ia, and (b) measuring the clustering pattern of X-ray selected AGN at a median redshift of z~1. Each component of the method can in itself provide interesting constraints on the cosmological parameters, especially under our anticipation that we will reduce the corresponding random and systematic errors significantly. However, by joining their likelihood functions we will be able to put stringent cosmological constraints and break the known degeneracies between the dark energy equation of state (whether it is constant or variable) and the matter content of the universe and provide a powerful and alternative route to measure the contribution to the global dynamics and the equation of state of dark energy. A preliminary joint analysis of X-ray selected AGN (based on the largest to-date XMM survey; the 2XMM) and the currently largest SNIa sample (Hicken et al.), using as priors a flat universe and the WMAP5 normalization of the power-spectrum, provides: Omega_m=0.27+-0.02 and w=-0.96+-0.07. Equivalent and consistent results are provided by the joint analysis of X-ray selected AGN clustering and the latest Baryonic Acoustic Oscillation measures, providing: Omega_m=0.27+-0.02 and w=-0.97+-0.04.

  15. Reflection Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX ECoop Inc Jump to:Newberg,Energy LLCALLETEREFURecent content inForestryReeseRefgas

  16. Aeromagnetic Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmental Jump to:EAand DaltonSolar EnergyAerodyn Energiesysteme GmbHOpenAl.,

  17. Hydro-Gravitational-Dynamics of Planets and Dark Energy

    E-Print Network [OSTI]

    Carl H. Gibson; Rudolph E. Schild

    2008-08-24

    Self-gravitational fluid mechanical methods termed hydro-gravitational-dynamics (HGD) predict plasma fragmentation 0.03 Myr after the turbulent big bang to form protosuperclustervoids, turbulent protosuperclusters, and protogalaxies at the 0.3 Myr transition from plasma to gas. Linear protogalaxyclusters fragment at 0.003 Mpc viscous-inertial scales along turbulent vortex lines or in spirals, as observed. The plasma protogalaxies fragment on transition into white-hot planet-mass gas clouds (PFPs) in million-solar-mass clumps (PGCs) that become globular-star-clusters (GCs) from tidal forces or dark matter (PGCs) by freezing and diffusion into 0.3 Mpc halos with 97% of the galaxy mass. The weakly collisional non-baryonic dark matter diffuses to > Mpc scales and frag-ments to form galaxy cluster halos. Stars and larger planets form by binary mergers of the trillion PFPs per PGC on 0.03 Mpc galaxy accretion disks. Star deaths depend on rates of planet accretion and internal star mixing. Moderate accretion rates produce white dwarfs that evaporate surrounding gas planets by spin-radiation to form planetary nebulae before Supernova Ia events, dimming some events to give systematic distance errors misinterpreted as the dark energy hypothesis and overestimates of the universe age. Failures of standard LCDM cosmological models reflect not only obsolete Jeans 1902 fluid mechanical assumptions, but also failures of standard turbulence models that claim the cascade of turbulent kinetic energy is from large scales to small. Because turbulence is always driven at all scales by inertial-vortex forces the turbulence cascade is always from small scales to large.

  18. CAN COUPLED DARK ENERGY SPEED UP THE BULLET CLUSTER?

    SciTech Connect (OSTI)

    Lee, Jounghun; Baldi, Marco E-mail: marco.baldi@universe-cluster.de

    2012-03-01

    It has been recently shown that the observed morphological properties of the Bullet Cluster can be accurately reproduced in hydrodynamical simulations only when the infall pairwise velocity V{sub c} of the system exceeds 3000 km s{sup -1} (or at least possibly 2500 km s{sup -1}) at the pair separation of 2R{sub vir}, where R{sub vir} is the virial radius of the main cluster, and that the probability of finding such a bullet-like system is extremely low in the standard {Lambda} cold dark matter ({Lambda}CDM) cosmology. We suggest here the fifth force mediated by coupled dark energy (cDE) as a possible velocity-enhancing mechanism and investigate its effect on the infall velocities of bullet-like systems from the Coupled Dark Energy Cosmological Simulations public database. Five different cDE models are considered: three with constant coupling and exponential potential, one with exponential coupling and exponential potential, and one with constant coupling and supergravity potential. For each model, after identifying the bullet-like systems, we determine the probability density distribution of their infall velocities at pair separations of (2-3)R{sub vir}. Approximating each probability density distribution as a Gaussian, we calculate the cumulative probability of finding a bullet-like system with V{sub c} {>=} 3000 km s{sup -1} or V{sub c} {>=} 2500 km s{sup -1}. Our results show that in all of the five cDE models the cumulative probabilities increase compared to the {Lambda}CDM case and that in the model with exponential coupling P(V{sub c} {>=} 2500 km s{sup -1}) exceeds 10{sup -4}. The physical interpretations and cosmological implications of our results are provided.

  19. Neutrinos and dark energy after Planck and BICEP2: data consistency tests and cosmological parameter constraints

    E-Print Network [OSTI]

    Jing-Fei Zhang; Jia-Jia Geng; Xin Zhang

    2014-10-17

    The detection of the B-mode polarization of the cosmic microwave background (CMB) by the BICEP2 experiment implies that the tensor-to-scalar ratio $r$ should be involved in the base standard cosmology. In this paper, we extend the $\\Lambda$CDM+$r$+neutrino/dark radiation models by replacing the cosmological constant with the dynamical dark energy with constant $w$. Four neutrino plus dark energy models are considered, i.e., the $w$CDM+$r+\\sum m_\

  20. Energy Conservation Thru Steam Trap Surveys and Preventive Maintenance Programs 

    E-Print Network [OSTI]

    Boynton, T.; Dewhirst, B.

    1980-01-01

    justification for the survey program. Defective steam traps and their energy characteristics will also be discussed. An on-going preventive maintenance program can be initiated from the information derived from the survey. Sustained energy efficiency...

  1. Testing Loop Quantum Gravity and Electromagnetic Dark Energy in Superconductors

    E-Print Network [OSTI]

    Clovis Jacinto de Matos

    2009-08-06

    In 1989 Cabrera and Tate reported an anomalous excess of mass of the Cooper pairs in rotating thin Niobium rings. So far, this experimental result never received a proper theoretical explanation in the context of superconductor's physics. In the present work we argue that what Cabrera and Tate interpreted as an anomalous excess of mass can also be associated with a deviation from the classical gravitomagnetic Larmor theorem due to the presence of dark energy in the superconductor, as well as with the discrete structure of the area of the superconducting Niobium ring as predicted by Loop Quantum Gravity. From Cabrera and Tate measurements we deduce that the quantization of spacetime in superconducting circular rings occurs at the Planck-Einstein scale $l_{PE} = (\\hbar G/c^3 \\Lambda)^{1/4}\\sim 3.77\\times 10 ^{-5} m$, instead of the Planck scale $l_{P} =(\\hbar G / c^3)^{1/2}=1.61 \\times 10 ^{-35} m$, with an Immirzi parameter which depends on the specific critical temperature of the superconducting material and on the area of the ring. The stephan-Boltzmann law for quantized areas delimited by superconducting rings is predicted, and an experimental concept based on the electromagnetic black-body radiation emitted by this surfaces, is proposed to test loop quantum gravity and electromagnetic dark energy in superconductors.

  2. Avoiding Boltzmann Brain domination in holographic dark energy models

    E-Print Network [OSTI]

    R. Horvat

    2015-09-14

    In a spatially infinite and eternal universe approaching ultimately a de Sitter (or quasi-de Sitter) regime, structure can form by thermal fluctuations as such a space is thermal. The models of Dark Energy invoking holographic principle fit naturally into such a category, and spontaneous formation of isolated brains in otherwise empty space seems the most perplexing, creating the paradox of Boltzmann Brains (BB). It is thus appropriate to ask if such models can be made free from domination by Boltzmann Brains. Here we consider only the simplest model, but adopt both the local and the global viewpoint in the description of the Universe. In the former case, we find that if a parameter $c$, which modulates the Dark Energy density, lies outside the exponentially narrow strip around the most natural $c = 1$ line, the theory is rendered BB-safe. In the later case, the bound on $c$ is exponentially stronger, and seemingly at odds with those bounds on $c$ obtained from various observational tests.

  3. Avoiding Boltzmann Brain domination in holographic dark energy models

    E-Print Network [OSTI]

    Horvat, R

    2015-01-01

    In a spatially infinite and eternal universe approaching ultimately a de Sitter (or quasi-de Sitter) regime, structure can form by thermal fluctuations as such a space is thermal. The models of Dark Energy invoking holographic principle fit naturally into such a category, and spontaneous formation of isolated brains in otherwise empty space seems the most perplexing, creating the paradox of Boltzmann Brains (BB). It is thus appropriate to ask if such models can be made free from domination by Boltzmann Brains. Here we consider only the simplest model, but adopt both the local and the global viewpoint in the description of the Universe. In the former case, we find that if a parameter $c$, which modulates the Dark Energy density, lies outside the exponentially narrow strip around the most natural $c = 1$ line, the theory is rendered BB-safe. In the later case, the bound on $c$ is exponentially stronger, and seemingly at odds with those bounds on $c$ obtained from various observational tests.

  4. Avoiding Boltzmann Brain domination in holographic dark energy models

    E-Print Network [OSTI]

    R. Horvat

    2015-02-23

    In a spatially infinite and eternal universe approaching ultimately a de Sitter (or quasi-de Sitter) regime, structure can form by thermal fluctuations as such a space is thermal. The models of Dark Energy invoking holographic principle fit naturally into such a category, and spontaneous formation of isolated brains in otherwise empty space seems the most perplexing, creating the paradox of Boltzmann Brains (BB). It is thus appropriate to ask if such models can be made free from domination by Boltzmann Brains. Here we consider only the simplest model, but adopt both the local and the global viewpoint in the description of the Universe. In the former case, we find that if a parameter $c$, which modulates the Dark Energy density, lies outside the exponentially narrow strip around the most natural $c = 1$ line, the theory is rendered BB-safe. In the later case, the bound on $c$ is exponentially stronger, and seemingly at odds with those bounds on $c$ obtained from various observational tests.

  5. Exploring uncertainties in dark energy constraints using current observational data with Planck 2015 distance priors

    E-Print Network [OSTI]

    Wang, Yun

    2015-01-01

    We explore the systematic uncertainties in dark energy constraints using the latest observational data from Type Ia Supernovae (SNe Ia), galaxy clustering, and cosmic microwave background anisotropy (CMB) data. We use the Joint Lightcurve Analysis (JLA) set of 740 SNe Ia, galaxy clustering measurements of H(z)s and D_A(z)/s (where s is the sound horizon at the drag epoch) from the Sloan Digital Sky Survey (SDSS) at z=0.35 (SDSS DR7) and z=0.57 (BOSS DR11), and the distance priors that we have derived from the 2015 Planck data (we present the mean values and covariance matrices required for using these). We find that omitting the BOSS DR11 measurement of H(z)s at z=0.57 leads to more concordant cosmological constraints, indicative of possible systematic uncertainties that affect the measurement of the line-of-sight galaxy clustering. We also find that flux-averaging of SNe Ia at z>= 0.5 gives significantly tighter constraints on dark energy; this can be due to the reduction in the distance measurement bias fro...

  6. Damped Oscillating Dark Energy: Ideal Fluid and Scalar-Tensor description

    E-Print Network [OSTI]

    Nilay Bostan; Ekrem Aydiner

    2015-08-12

    In this paper, we study damped oscillating form of dark energy for explaining dynamics of universe. First of all, we consider universe is filled with an ideal fluid which has damped oscillating dark energy in terms of this case we calculate several physical quantities such as Hubble parameter, acceleration parameter, energy density, pressure and others for dark energy, dark energy-matter coupling and non-coupling cases. Secondly, we consider as universe is filled with scalar field instead of an ideal fluid we obtain these physical quantities in terms of scalar potential and kinetic term for the same cases in scalar-tensor formalism. Finally, we show that ideal fluid description and scalar-tensor description of dark energy give mathematically equivalent results for this EoS parameter, even if they haven't same physical meaning.

  7. Damped Oscillating Dark Energy: Ideal Fluid and Scalar-Tensor description

    E-Print Network [OSTI]

    Bostan, Nilay

    2015-01-01

    In this paper, we study damped oscillating form of dark energy for explaining dynamics of universe. First of all, we consider universe is filled with an ideal fluid which has damped oscillating dark energy in terms of this case we calculate several physical quantities such as Hubble parameter, acceleration parameter, energy density, pressure and others for dark energy, dark energy-matter coupling and non-coupling cases. Secondly, we consider as universe is filled with scalar field instead of an ideal fluid we obtain these physical quantities in terms of scalar potential and kinetic term for the same cases in scalar-tensor formalism. Finally, we show that ideal fluid description and scalar-tensor description of dark energy give mathematically equivalent results for this EoS parameter, even if they haven't same physical meaning.

  8. Dark energy effects on the Lyman-alpha forest

    E-Print Network [OSTI]

    M. Viel; S. Matarrese; Tom Theuns; D. Munshi; Yun Wang

    2003-02-28

    In quintessence models, the dark energy content of the universe is described by a slowly rolling scalar field whose pressure and energy density obey an equation of state of the form p=w $\\rho$; w is in general a function of time such that wforest to constrain w, using semi-analytical techniques to model the intergalactic medium (IGM). A different value of w changes both the growth factor and the Hubble parameter as a function of time. The resulting change in the optical depth distribution affects the optical depth power spectrum, the number of regions of high transmission per unit redshift and the cross-correlation coefficient of spectra of quasar pairs. These can be detected in current data, provided we have independent estimates of the thermal state of the IGM, its ionization parameter and the baryon density.

  9. On the dark energy rest frame and the CMB

    E-Print Network [OSTI]

    Jose Beltran Jimenez; Antonio L. Maroto

    2008-12-11

    Dark energy is usually parametrized as a perfect fluid with negative pressure and a certain equation of state. Besides, it is supposed to interact very weakly with the rest of the components of the universe and, as a consequence, there is no reason to expect it to have the same large-scale rest frame as matter and radiation. Thus, apart from its equation of state $w$ and its energy density $\\Omega_{DE}$ one should also consider its velocity as a free parameter to be determined by observations. This velocity defines a cosmological preferred frame, so the universe becomes anisotropic and, therefore, the CMB temperature fluctuations will be affected, modifying mainly the dipole and the quadrupole.

  10. The Gaia-ESO Survey: a quiescent Milky Way with no significant dark/stellar accreted disc

    E-Print Network [OSTI]

    Ruchti, G R; Feltzing, S; Serenelli, A M; McMillan, P; Lind, K; Bensby, T; Bergemann, M; Asplund, M; Vallenari, A; Flaccomio, E; Pancino, E; Korn, A J; Recio-Blanco, A; Bayo, A; Carraro, G; Costado, M T; Damiani, F; Heiter, U; Hourihane, A; Jofre, P; Kordopatis, G; Lardo, C; de Laverny, P; Monaco, L; Morbidelli, L; Sbordone, L; Worley, C C; Zaggia, S

    2015-01-01

    According to our current cosmological model, galaxies like the Milky Way are expected to experience many mergers over their lifetimes. The most massive of the merging galaxies will be dragged towards the disc-plane, depositing stars and dark matter into an accreted disc structure. In this work, we utilize the chemo-dynamical template developed in Ruchti et al. to hunt for accreted stars. We apply the template to a sample of 4,675 stars in the third internal data release from the Gaia-ESO Spectroscopic Survey. We find a significant component of accreted halo stars, but find no evidence of an accreted disc component. This suggests that the Milky Way has had a rather quiescent merger history since its disc formed some 8-10 billion years ago and therefore possesses no significant dark matter disc.

  11. Dark Energy Rules the Universe (and why the dinosaurs do not!) (LBNL Science at the Theater)

    ScienceCinema (OSTI)

    Linder, Eric

    2011-04-28

    The revolutionary discovery that the expansion of the universe is speeding up, not slowing down from gravity, means that 75 percent of our universe consists of mysterious dark energy. Berkeley Lab theoretical physicist Eric Linder delves into the mystery of dark energy as part of the Science in the Theatre lecture series on Nov. 24, 2008.

  12. Equation of state description of the dark energy transition between quintessence and phantom regimes

    E-Print Network [OSTI]

    Hrvoje Stefancic

    2005-12-01

    The dark energy crossing of the cosmological constant boundary (the transition between the quintessence and phantom regimes) is described in terms of the implicitly defined dark energy equation of state. The generalizations of the models explicitly constructed to exhibit the crossing provide the insight into the cancellation mechanism which makes the transition possible.

  13. Supernova constraints on Multi-coupled Dark Energy

    E-Print Network [OSTI]

    Arpine Piloyan; Valerio Marra; Marco Baldi; Luca Amendola

    2013-07-09

    The persisting consistency of ever more accurate observational data with the predictions of the standard LCDM cosmological model puts severe constraints on possible alternative scenarios, but still does not shed any light on the fundamental nature of the cosmic dark sector.As large deviations from a LCDM cosmology are ruled out by data, the path to detect possible features of alternative models goes necessarily through the definition of cosmological scenarios that leave almost unaffected the background and -- to a lesser extent -- the linear perturbations evolution of the universe. In this context,the Multi-coupled DE (McDE) model was proposed by Baldi 2012 as a particular realization of an interacting Dark Energy field characterized by an effective screening mechanism capable of suppressing the effects of the coupling at the background and linear perturbation level. In the present paper, for the first time, we challenge the McDE scenario through a direct comparison with real data, in particular with the luminosity distance of Type Ia supernovae. By studying the existence and stability conditions of the critical points of the associated background dynamical system, we select only the cosmologically consistent solutions, and confront their background expansion history with data. Confirming previous qualitative results, the McDE scenario appears to be fully consistent with the adopted sample of Type Ia supernovae, even for coupling values corresponding to an associated scalar fifth-force about four orders of magnitude stronger than standard gravity. Our analysis demonstrates the effectiveness of the McDE background screening, and shows some new non-trivial asymptotic solutions for the future evolution of the universe. Our results show how the background expansion history might be highly insensitive to the fundamental nature and to the internal complexity of the dark sector. [Abridged

  14. 9/18/09 2:43 PM'Big Wave' Theory Offers Alternative to Dark Energy // Current Page 1 of 11http://current.com/items/90718274_big-wave-theory-offers-alternative-to-dark-energy.htm

    E-Print Network [OSTI]

    Temple, Blake

    9/18/09 2:43 PM'Big Wave' Theory Offers Alternative to Dark Energy // Current Page 1 of 11http://current.com/items/90718274_big-wave-theory-offers-alternative-to-dark-energy.htm login | register |home tv shows schedule to Dark Energy // Current Page 2 of 11http://current.com/items/90718274_big-wave-theory-offers-alternative-to-dark-energy

  15. UP TO 100,000 RELIABLE STRONG GRAVITATIONAL LENSES IN FUTURE DARK ENERGY EXPERIMENTS

    SciTech Connect (OSTI)

    Serjeant, S.

    2014-09-20

    The Euclid space telescope will observe ?10{sup 5} strong galaxy-galaxy gravitational lens events in its wide field imaging survey over around half the sky, but identifying the gravitational lenses from their observed morphologies requires solving the difficult problem of reliably separating the lensed sources from contaminant populations, such as tidal tails, as well as presenting challenges for spectroscopic follow-up redshift campaigns. Here I present alternative selection techniques for strong gravitational lenses in both Euclid and the Square Kilometre Array, exploiting the strong magnification bias present in the steep end of the H? luminosity function and the H I mass function. Around 10{sup 3} strong lensing events are detectable with this method in the Euclid wide survey. While only ?1% of the total haul of Euclid lenses, this sample has ?100% reliability, known source redshifts, high signal-to-noise, and a magnification-based selection independent of assumptions of lens morphology. With the proposed Square Kilometre Array dark energy survey, the numbers of reliable strong gravitational lenses with source redshifts can reach 10{sup 5}.

  16. Cool Trends in District Energy: A Survey of Thermal Energy Storage...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    in District Energy: A Survey of Thermal Energy Storage Use in District Energy Utility Applications, June 2005 Cool Trends in District Energy: A Survey of Thermal Energy Storage Use...

  17. COLLOQUIUM: Probing the Accelerating Universe with the Dark Energy Survey |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room News PublicationsAudits &BradburyMay 1, 2013, 4:15pm ColloquiaPhysics Lab October

  18. A bound system in the expanding universe with modified holographic Ricci dark energy and dark matter

    E-Print Network [OSTI]

    En-Kun Li; Yu Zhang; Jin-Ling Geng; Peng-Fei Duan

    2015-02-12

    The evolution of a bound system in the expanding background has been investigated in this paper. The background is described by a FRW universe with the modified holographic dark energy model, whose equation of state parameter changes with time and can cross the phantom boundary. To study the evolution of the bound system, an interpolating metric is considered, and on this basis the geodesics of a test particle are given. The equation of motion and the effective potential are also derived from the geodesics. By studying the the effective potential and the evolution of the radius of a test particle in the bound system of the Milky Way galaxy, we have found that the galaxy would go through three stages: expands from a singular point; stays in a discoid for a period of time; big rip in the future. With the help of analysing the critical angular momentum, we find that the test particle needs less angular momentum to escape from the center mass as time passes.

  19. Introduction to Modified Gravity and Gravitational Alternative for Dark Energy

    E-Print Network [OSTI]

    S. Nojiri; S. D. Odintsov

    2006-03-31

    We review various modified gravities considered as gravitational alternative for dark energy. Specifically, we consider the versions of $f(R)$, $f(G)$ or $f(R,G)$ gravity, model with non-linear gravitational coupling or string-inspired model with Gauss-Bonnet-dilaton coupling in the late universe where they lead to cosmic speed-up. It is shown that some of such theories may pass the Solar System tests. On the same time, it is demonstrated that they have quite rich cosmological structure: they may naturally describe the effective (cosmological constant, quintessence or phantom) late-time era with a possible transition from decceleration to acceleration thanks to gravitational terms which increase with scalar curvature decrease. The possibility to explain the coincidence problem as the manifestation of the universe expansion in such models is mentioned. The late (phantom or quintessence) universe filled with dark fluid with inhomogeneous equation of state (where inhomogeneous terms are originated from the modified gravity) is also described.

  20. Supernova constraints on Multi-coupled Dark Energy

    E-Print Network [OSTI]

    Piloyan, Arpine; Baldi, Marco; Amendola, Luca

    2013-01-01

    The persisting consistency of ever more accurate observational data with the predictions of the standard LCDM cosmological model puts severe constraints on possible alternative scenarios, but still does not shed any light on the fundamental nature of the cosmic dark sector.As large deviations from a LCDM cosmology are ruled out by data, the path to detect possible features of alternative models goes necessarily through the definition of cosmological scenarios that leave almost unaffected the background and -- to a lesser extent -- the linear perturbations evolution of the universe. In this context,the Multi-coupled DE (McDE) model was proposed by Baldi 2012 as a particular realization of an interacting Dark Energy field characterized by an effective screening mechanism capable of suppressing the effects of the coupling at the background and linear perturbation level. In the present paper, for the first time, we challenge the McDE scenario through a direct comparison with real data, in particular with the lumi...

  1. Linear Perturbation constraints on Multi-coupled Dark Energy

    E-Print Network [OSTI]

    Piloyan, Arpine; Baldi, Marco; Amendola, Luca

    2014-01-01

    The Multi-coupled Dark Energy (McDE) scenario has been recently proposed as a specific example of a cosmological model characterized by a non-standard physics of the dark sector of the universe that nevertheless gives an expansion history which does not significantly differ from the one of the standard $\\Lambda $CDM model. In this work, we present the first constraints on the McDE scenario obtained by comparing the predicted evolution of linear density perturbations with a large compilation of recent data sets for the growth rate $f\\sigma_{8}$, including 6dFGS, LRG, BOSS, WiggleZ and VIPERS. Confirming qualitative expectations, growth rate data provide much tighter bounds on the model parameters as compared to the extremely loose bounds that can be obtained when only the background expansion history is considered. In particular, the $95\\%$ confidence level on the coupling strength $|\\beta |$ is reduced from $|\\beta |\\leq 83$ (background constraints only) to $|\\beta |\\leq 0.88$ (background and linear perturbat...

  2. AIC, BIC, Bayesian evidence against the interacting dark energy model

    E-Print Network [OSTI]

    Marek Szydlowski; Adam Krawiec; Aleksandra Kurek; Michal Kamionka

    2014-12-03

    Recent astronomical observations have indicated that the Universe is in the phase of accelerated expansion. While there are many cosmological models which try to explain this phenomenon, we focus on the interacting $\\Lambda$CDM model where the interaction between the dark energy and dark matter sectors takes place. This model is compared to its simpler alternative---the $\\Lambda$CDM model. To choose between these models the likelihood ratio test was applied as well as the model comparison methods (employing Occam's principle): the Akaike information criterion (AIC), the Bayesian information criterion (BIC) and the Bayesian evidence. Using the current astronomical data: SNIa (Union2.1), $h(z)$, BAO, Alcock--Paczynski test and CMB we evaluated both models. The analyses based on the AIC indicated that there is less support for the interacting $\\Lambda$CDM model when compared to the $\\Lambda$CDM model, while those based on the BIC indicated that there is the strong evidence against it in favor the $\\Lambda$CDM model. Given the weak or almost none support for the interacting $\\Lambda$CDM model and bearing in mind Occam's razor we are inclined to reject this model.

  3. Ground Gravity Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIXsource History View New PagesInformationEnergy Information| OpenOpen EnergySurvey

  4. ISW-Galaxy Cross Correlation:A probe of Dark Energy clustering and distribution of Dark Matter tracers

    E-Print Network [OSTI]

    Khosravi, Shahram; Baghram, Shant

    2015-01-01

    The Integrated Sachs Wolfe (ISW) cross correlation with the galaxy distribution in late time is a promising tool to constrain the dark energy properties. In this work we study the effect of dark energy clustering on the ISW-galaxy cross correlation. Indicating the fact that the bias parameter between the distribution of the galaxies and the underlying dark matter introduce a degeneracy and complications. We argue that as the time of the galaxy's host halo formation is different from the observation time, we have to consider the evolution of the halo bias parameter. We indicate that any deviation from $\\Lambda$CDM model will change the evolution of the bias as well. Also we show that the halo bias strongly depends on the sub-sample of galaxies which is chosen for cross correlation. We show that joint kernel of ISW effect and the galaxy distribution have the dominant effect on the observed signal, accordingly we can enhance the signal of a specific dark energy model by choosing an appropriate tracer. More speci...

  5. Large-Scale Magnetic Fields, Dark Energy and QCD

    E-Print Network [OSTI]

    Federico R. Urban; Ariel R. Zhitnitsky

    2010-08-20

    Cosmological magnetic fields are being observed with ever increasing correlation lengths, possibly reaching the size of superclusters, therefore disfavouring the conventional picture of generation through primordial seeds later amplified by galaxy-bound dynamo mechanisms. In this paper we put forward a fundamentally different approach that links such large-scale magnetic fields to the cosmological vacuum energy. In our scenario the dark energy is due to the Veneziano ghost (which solves the $U(1)_A$ problem in QCD). The Veneziano ghost couples through the triangle anomaly to the electromagnetic field with a constant which is unambiguously fixed in the standard model. While this interaction does not produce any physical effects in Minkowski space, it triggers the generation of a magnetic field in an expanding universe at every epoch. The induced energy of the magnetic field is thus proportional to cosmological vacuum energy: $\\rho_{EM}\\simeq B^2 \\simeq (\\frac{\\alpha}{4\\pi})^2 \\rho_{DE}$, $\\rho_{DE}$ hence acting as a source for the magnetic energy $\\rho_{EM}$. The corresponding numerical estimate leads to a magnitude in the nG range. There are two unique and distinctive predictions of our proposal: an uninterrupted active generation of Hubble size correlated magnetic fields throughout the evolution of the universe; the presence of parity violation on the enormous scales $1/H$, which apparently has been already observed in CMB. These predictions are entirely rooted into the standard model of particle physics.

  6. Puzzles of the dark energy in the universe - phantom

    E-Print Network [OSTI]

    Mariusz P. Dabrowski

    2014-12-30

    This paper is devoted to some simple approach based on general physics tools to describe the physical properties of a hypothetical particle which can be the source of dark energy in the Universe known as phantom. Phantom is characterized by the fact that it possesses negative momentum and kinetic energy and that it gives large negative pressure which acts as antigravity. We consider phantom harmonic oscillator in comparison to a standard harmonic oscillator. By using the first law of thermodynamics we explain why the energy density of the Universe grows when it is filled with phantom. We also show how the collision of phantom with a standard particle leads to exploration of energy from the former by the latter (i.e. from phantom to the standard) if their masses are different. The most striking of our conclusions is that the collision of phantom and standard particles of the same masses is impossible unless both of them are at rest and suddenly start moving with the opposite velocities and kinetic energies. This effect is a classic analogue of a quantum mechanical particle pair creation in a strong electric field or in physical vacuum.

  7. Relic Dark energy from Trans-Planckian Regime

    E-Print Network [OSTI]

    Laura Mersini; Mar Bastero-Gil; Panagiota Kanti

    2001-06-06

    As yet, there is no underlying fundamental theory for the transplanckian regime. There is a need to address the issue of how the observables in our present universe are affected by processes that may have occured during the transplanckian regime. A particular feature of the family of dispersion functions chosen is the production of ultralow frequencies at very high momenta $k> M_P$. We name the range of the ultralow energy modes (of very short distances) that have frequencies equal or less than the current Hubble rate $H_0$ as the $\\it{tail}$ modes. These modes are still frozen today due to the expansion of the universe. We calculate their energy today and show that the $tail$ provides a strong candidate for the {\\it dark energy} of the universe. During inflation, their energy is about 122-123 orders of magnitude smaller than the total energy. We present the exact solutions and show that: the CMBR spectrum is that of a (nearly) black body, and that the adiabatic vacuum is the only choice for the initial conditions. Finally, some of these results can also be applied to black hole physics.

  8. Is the Interacting Dark Matter Scenario an Alternative to Dark Energy ?

    E-Print Network [OSTI]

    Basilakos, S

    2008-01-01

    We study the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Assuming that the dark matter obeys the collisional Boltzmann equation, we can derive analytical solutions of the global density evolution, which can accommodate an accelerated expansion, equivalent to either the {\\em quintessence} or the standard $\\Lambda$ models. We also find realistic solutions in which the present time is located after the inflection point.

  9. Structure formation in modified gravity models alternative to dark energy

    E-Print Network [OSTI]

    Kazuya Koyama

    2006-01-10

    We study structure formation in phenomenological models in which the Friedmann equation receives a correction of the form $H^{\\alpha}/r_c^{2-\\alpha}$, which realize an accelerated expansion without dark energy. In order to address structure formation in these model, we construct simple covariant gravitational equations which give the modified Friedmann equation with $\\alpha=2/n$ where $n$ is an integer. For $n=2$, the underlying theory is known as a 5D braneworld model (the DGP model). Thus the models interpolate between the DGP model ($n=2, \\alpha=1$) and the LCDM model in general relativity ($n \\to \\infty, \\alpha \\to 0$). Using the covariant equations, cosmological perturbations are analyzed. It is shown that in order to satisfy the Bianchi identity at a perturbative level, we need to introduce a correction term $E_{\\mu \

  10. Structure formation in modified gravity models alternative to dark energy

    E-Print Network [OSTI]

    Koyama, K

    2006-01-01

    We study structure formation in phenomenological models in which the Friedmann equation receives a correction of the form $H^{\\alpha}/r_c^{2-\\alpha}$, which realize an accelerated expansion without dark energy. In order to address structure formation in these model, we construct simple covariant gravitational equations which give the modified Friedmann equation with $\\alpha=2/n$ where $n$ is an integer. For $n=2$, the underlying theory is known as a 5D braneworld model (the DGP model). Thus the models interpolate between the DGP model ($n=2, \\alpha=1$) and the LCDM model in general relativity ($n \\to \\infty, \\alpha \\to 0$). Using the covariant equations, cosmological perturbations are analyzed. It is shown that in order to satisfy the Bianchi identity at a perturbative level, we need to introduce a correction term $E_{\\mu \

  11. Non-Abelian condensates as alternative for dark energy

    E-Print Network [OSTI]

    Gal'tsov, Dmitri V

    2009-01-01

    We review basic features of cosmological models with large-scale classical non-Abelian Yang-Mills (YM) condensates. There exists a unique SU(2) YM configuration (generalizable to larger gauge groups) compatible with homogeneity and isotropy of the three-space which is parameterized by a single scalar field. In the past various aspects of Einstein-Yang-Mills (EYM) cosmology were discussed in the context of the Early Universe. Due to conformal invariance, solvable EYM FRW models exist both on the classical and quantum levels. To develop the YM model for dark energy one has to find mechanisms of the conformal symmetry breaking. We discuss the Born-Infeld generalization and some phenomenological models motivated by quantum corrections exploring possibility of transient DE and phantom regimes.

  12. Non-Abelian condensates as alternative for dark energy

    E-Print Network [OSTI]

    Dmitri V. Gal'tsov

    2008-12-31

    We review basic features of cosmological models with large-scale classical non-Abelian Yang-Mills (YM) condensates. There exists a unique SU(2) YM configuration (generalizable to larger gauge groups) compatible with homogeneity and isotropy of the three-space which is parameterized by a single scalar field. In the past various aspects of Einstein-Yang-Mills (EYM) cosmology were discussed in the context of the Early Universe. Due to conformal invariance, solvable EYM FRW models exist both on the classical and quantum levels. To develop the YM model for dark energy one has to find mechanisms of the conformal symmetry breaking. We discuss the Born-Infeld generalization and some phenomenological models motivated by quantum corrections exploring possibility of transient DE and phantom regimes.

  13. Anisotropic dark energy model with a hybrid scale factor

    E-Print Network [OSTI]

    B. Mishra; S. K. Tripathy

    2015-11-08

    Anisotropic dark energy model with dynamic pressure anisotropies along different spatial directions is constructed at the backdrop of a spatially homogeneous diagonal Bianchi type $V$ $(BV)$ space-time in the framework of General Relativity. A time varying deceleration parameter generating a hybrid scale factor is considered to simulate a cosmic transition from early deceleration to late time acceleration. We found that the pressure anisotropies along the $y-$ and $z-$ axes evolve dynamically and continue along with the cosmic expansion without being subsided even at late times. The anisotropic pressure along the $x-$axis becomes equal to the mean fluid pressure. At a late phase of cosmic evolution, the model enters into a phantom region. From a state finder diagnosis, it is found that the model overlaps with $\\Lambda$CDM at late phase of cosmic time.

  14. Cosmic slowing down of acceleration for several dark energy parametrizations

    SciTech Connect (OSTI)

    Magaña, Juan; Cárdenas, Víctor H.; Motta, Verónica, E-mail: juan.magana@uv.cl, E-mail: victor.cardenas@uv.cl, E-mail: veronica.motta@uv.cl [Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso (Chile)

    2014-10-01

    We further investigate slowing down of acceleration of the universe scenario for five parametrizations of the equation of state of dark energy using four sets of Type Ia supernovae data. In a maximal probability analysis we also use the baryon acoustic oscillation and cosmic microwave background observations. We found the low redshift transition of the deceleration parameter appears, independently of the parametrization, using supernovae data alone except for the Union 2.1 sample. This feature disappears once we combine the Type Ia supernovae data with high redshift data. We conclude that the rapid variation of the deceleration parameter is independent of the parametrization. We also found more evidence for a tension among the supernovae samples, as well as for the low and high redshift data.

  15. Mega-masers, Dark Energy and the Hubble Constant

    SciTech Connect (OSTI)

    Lo, Fred K. Y.

    2007-10-15

    Powerful water maser emission (water mega-masers) can be found in accretion disks in the nuclei of some galaxies. Besides providing a measure of the mass at the nucleus, such mega-masers can be used to determine the distance to the host galaxy, based on a kinematic model. We will explain the importance of determining the Hubble Constant to high accuracy for constraining the equation of state of Dark Energy and describe the Mega-maser Cosmology Project that has the goal of determining the Hubble Constant to better than 3%. Time permitting, we will also present the scientific capabilities of the current and future NRAO facilities: ALMA, EVLA, VLBA and GBT, for addressing key astrophysical problems

  16. Exploring holographic dark energy model with Sandage-Loeb test

    E-Print Network [OSTI]

    Hongbao Zhang; Wuhan Zhong; Zong-Hong Zhu; Song He

    2007-11-14

    Taking into account that Sandage-Loeb test is unique in its coverage of the redshift desert and available in the near future, we explore the cosmic time evolution behavior of the source redshift for holographic dark energy model, an important competing cosmological model. As a result, we find that Sandage-Loeb test can provide a extremely strong bound on $\\Omega^0_m$, while its constraint on another dimensionless parameter $\\lambda$ is weak. In addition, it is proposed here for the first time that we can also constrain various cosmological model by measuring the value of $z_{max}$ at which the peak of redshift velocity occurs. Combining this new proposed method with the traditional Sandage-Loeb test, we should be able to provide a better constraint on $\\lambda$, at least from the theoretical perspective.

  17. DUNE: The Dark Universe Explorer

    E-Print Network [OSTI]

    A. Refregier; O. Boulade; Y. Mellier; B. Milliard; R. Pain; J. Michaud; F. Safa; A. Amara; P. Astier; E. Barrelet; E. Bertin; S. Boulade; C. Cara; A. Claret; L. Georges; R. Grange; J. Guy; C. Koeck; L. Kroely; C. Magneville; N. Palanque-Delabrouille; N. Regnault; G. Smadja; C. Schimd; Z. Sun

    2006-10-03

    Understanding the nature of Dark Matter and Dark Energy is one of the most pressing issues in cosmology and fundamental physics. The purpose of the DUNE (Dark UNiverse Explorer) mission is to study these two cosmological components with high precision, using a space-based weak lensing survey as its primary science driver. Weak lensing provides a measure of the distribution of dark matter in the universe and of the impact of dark energy on the growth of structures. DUNE will also include a complementary supernovae survey to measure the expansion history of the universe, thus giving independent additional constraints on dark energy. The baseline concept consists of a 1.2m telescope with a 0.5 square degree optical CCD camera. It is designed to be fast with reduced risks and costs, and to take advantage of the synergy between ground-based and space observations. Stringent requirements for weak lensing systematics were shown to be achievable with the baseline concept. This will allow DUNE to place strong constraints on cosmological parameters, including the equation of state parameter of the dark energy and its evolution from redshift 0 to 1. DUNE is the subject of an ongoing study led by the French Space Agency (CNES), and is being proposed for ESA's Cosmic Vision programme.

  18. Sudden Future Singularity models as an alternative to Dark Energy?

    E-Print Network [OSTI]

    Ghodsi, Hoda; Dabrowski, Mariusz P; Denkiewicz, Tomasz

    2011-01-01

    Current observational evidence does not yet exclude the possibility that dark energy could be in the form of phantom energy. A universe consisting of a phantom constituent will be driven toward a drastic end known as the `Big Rip' singularity where all the matter in the universe will be destroyed. Motivated by this possibility, other evolutionary scenarios have been explored by Barrow, including the phenomena which he called Sudden Future Singularities (SFS). In such a model it is possible to have a blow up of the pressure occurring at sometime in the future evolution of the universe while the energy density would remain unaffected. The particular evolution of the scale factor of the universe in this model that results in a singular behaviour of the pressure also admits acceleration in the current era. In this paper we will present the results of our confrontation of one example class of SFS models with the available cosmological data from high redshift supernovae, baryon acoustic oscillations (BAO) and the c...

  19. Chinese Geological Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmentalBowerbank,CammackFLIR JumpMaine:WestTexas: EnergyExportDLRGeological Survey Jump to:

  20. Mediation Survey Form | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematicsEnergyInterested Parties - WAPAEnergy May 28 Webinar to Focus on TribalMediaSurvey Form

  1. Role of generalized Ricci dark energy on Chameleon field in the emergent universe

    E-Print Network [OSTI]

    Surajit Chattopadhyay; Ujjal Debnath

    2011-07-14

    In this paper, we have considered the generalized Ricci dark energy (GRDE) and generalized holographic dark energy (GHDE) in the scenario of emergent universe. Fractional energy density and deceleration parameters for GRDE were derived under emergent universe scenario. Also role of GRDE on the Chameleon field in the emergent universe scenario has been examined. Finally, the behaviours of the Chameleon scalar field $\\phi$, corresponding potential $V$ and associated function $f$ were investigated in presence of GRDE.

  2. Energy Efficiency and Renewable Energy Network (EREN): Customer satisfaction survey

    SciTech Connect (OSTI)

    Anderson, A.V. [Information International Associates, Inc., Oak Ridge, TN (United States); Henderson, D.P. [Dept. of Energy, Oak Ridge, TN (United States). Office of Scientific and Technical Information

    1996-04-22

    The Energy Efficiency and Renewable Energy Network (EREN) Customer Satisfaction Survey was developed and executed in support of EREN`s continuous quality improvement (CQI) plan. The study was designed to provide information about the demographic make up of EREN users, the value or benefits they derive from EREN, the kinds and quality of services they want, their levels of satisfaction with existing services, their preferences in both the sources of service and the means of delivery, and to provide benchmark data for the establishment of continuous quality improvement measures. The survey was performed by soliciting voluntary participation from members of the EREN Users Group. It was executed in two phases; the first being conducted by phone using a randomly selected group; and the second being conducted electronically and which was open to all of the remaining members of the Users Group. The survey results are described.

  3. ENERGY STORAGE IN AQUIFERS - - A SURVEY OF RECENT THEORETICAL STUDIES

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2013-01-01

    temperature underground thermal energy storage. In Proc. Th~1980), Aquifer Thermal Energy Sto:t'age--·a survey, Invit.edal modeling of thermal energy storage in aquifers. In ~~-

  4. Vector theory of gravity: solution of dark energy problem

    E-Print Network [OSTI]

    Svidzinsky, Anatoly A

    2015-01-01

    We propose an alternative classical theory of gravity which assumes that background geometry of the Universe is fixed four dimensional Euclidean space and gravity is a vector field $A_{k}$ in this space which breaks the Euclidean symmetry. Direction of $A_{k}$ gives the time coordinate, while perpendicular directions are spatial coordinates. Vector gravitational field is coupled to matter universally and minimally through the equivalent metric $f_{ik}$ which is a functional of $A_{k}$. We show that such assumptions yield a unique theory of gravity, it is free of black holes and to the best of our knowledge it passes all available tests. For cosmology our theory predicts the same evolution of the Universe as general relativity with cosmological constant and zero spatial curvature. However, the present theory provides explanation of the dark energy as energy of gravitational field induced by the Universe expansion and yields, with no free parameters, the value of $\\Omega _{\\Lambda }=2/3\\approx 0.67$ which agree...

  5. Phantom Dark Energy Spinors in Einstein-Cartan Gravity Are Safe

    E-Print Network [OSTI]

    Chang, Yu-Chiao; Chen, Pisin

    2015-01-01

    A class of dynamical dark energy models is constructed through an extended version of fermion fields called ELKO spinors, which are spin one half with mass dimension one. We find that if the ELKO spinor interacts with torsion fields in a homogeneous and isotropic universe, then it does not imply any future dark energy singularity or any abrupt event, though the fermion has a negative kinetic energy. In fact, the equation of state of this dark energy model will asymptotically approach the value $w=-1$ from above without crossing the phantom divide and inducing therefore a de Sitter state. Consequently, we expect the model to be stable because no phantom field will be created. At late time, the torsion fields will vanish as the ELKO spinors dilute. As would be expected intuitively, this result is unaffected by the presence of cold dark matter although the proof is not as straightforward as in general relativity.

  6. Exploring Parameter Constraints on Quintessential Dark Energy: the Inverse Power Law Model

    E-Print Network [OSTI]

    Yashar, Mark; Abrahamse, Augusta; Albrecht, Andreas; Barnard, Michael

    2008-01-01

    We report on the results of a Markov Chain Monte Carlo (MCMC) analysis of an inverse power law (IPL) quintessence model using the Dark Energy Task Force (DETF) simulated data sets as a representation of future dark energy experiments. We generate simulated data sets for a Lambda-CDM background cosmology as well as a case where the dark energy is provided by a specific IPL fiducial model and present our results in the form of likelihood contours generated by these two background cosmologies. We find that the relative constraining power of the various DETF data sets on the IPL model parameters is broadly equivalent to the DETF results for the w_{0}-w_{a} parameterization of dark energy. Finally, we gauge the power of DETF "Stage 4" data by demonstrating a specific IPL model which, if realized in the universe, would allow Stage 4 data to exclude a cosmological constant at better than the 3-sigma level.

  7. Exploring parameter constraints on quintessential dark energy: The inverse power law model

    SciTech Connect (OSTI)

    Yashar, Mark; Bozek, Brandon; Abrahamse, Augusta; Albrecht, Andreas; Barnard, Michael

    2009-05-15

    We report on the results of a Markov chain Monte Carlo analysis of an inverse power law (IPL) quintessence model using the Dark Energy Task Force (DETF) simulated data sets as a representation of future dark energy experiments. We generate simulated data sets for a {lambda}CDM background cosmology as well as a case where the dark energy is provided by a specific IPL fiducial model, and present our results in the form of likelihood contours generated by these two background cosmologies. We find that the relative constraining power of the various DETF data sets on the IPL model parameters is broadly equivalent to the DETF results for the w{sub 0}-w{sub a} parametrization of dark energy. Finally, we gauge the power of DETF 'stage 4' data by demonstrating a specific IPL model which, if realized in the universe, would allow stage 4 data to exclude a cosmological constant at better than the 3{sigma} level.

  8. Exploring Parameter Constraints on Quintessential Dark Energy: the Inverse Power Law Model

    E-Print Network [OSTI]

    Mark Yashar; Brandon Bozek; Augusta Abrahamse; Andreas Albrecht; Michael Barnard

    2008-11-14

    We report on the results of a Markov Chain Monte Carlo (MCMC) analysis of an inverse power law (IPL) quintessence model using the Dark Energy Task Force (DETF) simulated data sets as a representation of future dark energy experiments. We generate simulated data sets for a Lambda-CDM background cosmology as well as a case where the dark energy is provided by a specific IPL fiducial model and present our results in the form of likelihood contours generated by these two background cosmologies. We find that the relative constraining power of the various DETF data sets on the IPL model parameters is broadly equivalent to the DETF results for the w_{0}-w_{a} parameterization of dark energy. Finally, we gauge the power of DETF "Stage 4" data by demonstrating a specific IPL model which, if realized in the universe, would allow Stage 4 data to exclude a cosmological constant at better than the 3-sigma level.

  9. Improved Dark Energy Constraints From ~ 100 New CfA Supernova...

    Office of Scientific and Technical Information (OSTI)

    with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al....

  10. Effects of ghost dark energy perturbations on the evolution of spherical overdensities

    E-Print Network [OSTI]

    Malekjani, Mohammad; Pace, Francesco

    2015-01-01

    While in the standard cosmological model the accelerated expansion of the Universe is explained by invoking the presence of the cosmological constant term, it is still unclear the true origin of this stunning observational fact. It is therefore interesting to explore alternatives to the simplest scenario, in particular by assuming a more general framework where the fluid responsible of the accelerated expansion is characterised by a time-dependant equation of state. Usually these models, dubbed dark energy models, are purely phenomenological, but in this work we concentrate on a theoretically justified model, the ghost dark energy model. Within the framework of the spherical collapse model, we evaluate effects of dark energy perturbations both at the linear and non-linear level and transfer these results into an observable quantity, the mass function, by speculatively taking into account contributions of dark energy to the mass of the halos. We showed that the growth rate is higher in ghost models and that pe...

  11. Testing of Dark Energy and a Solution of the Cosmological Constant Problem

    E-Print Network [OSTI]

    Vladimir Burdyuzha

    2014-01-19

    A probable solution of the cosmological constant problem was recently found. We propose that dark energy of the Universe is vacuum energy. Our Universe during its expansion is spending its vacuum energy for creation of new quantum states, but in the quantum regime phase transitions were more effective in reducing the vacuum energy than creation of new quantum states. Here we show how the 123 crisis orders of the vacuum energy are reduced by conventional physical processes in both the quantum and classical regimes of the Universe evolution. Numeral estimates of dark energy evolution are also presented.

  12. Power Law Entropy Corrected New-Agegraphic Dark Energy in Ho?ava-Lifshitz Cosmology

    E-Print Network [OSTI]

    K. Karami; A. Sheykhi; Mubasher Jamil; R. Myrzakulov; S. Ghaffari; A. Abdolmaleki

    2012-03-31

    We investigate the new agegraphic dark energy (NADE) model with power-law corrected entropy in the framework of Ho\\v{r}ava-Lifshitz cosmology. For a non-flat universe containing the interacting power-law entropy-corrected NADE (PLECNADE) with dark matter, we obtain the differential equation of the evolution of density parameter as well as the deceleration parameter. To study parametric behavior, we used an interesting form of state parameter as function of redshift $\\omega_{\\Lambda}(z)=\\omega_0+\\omega_1 z$. We found that phantom crossing occurs for the state parameter for a non-zero coupling parameter, thus supporting interacting dark energy model.

  13. Testing a DBI model for the unification of dark matter and dark energy with Gamma-Ray Bursts

    E-Print Network [OSTI]

    Ariadna Montiel; Nora Bretón

    2012-02-14

    We study the range of consistency of a model based on a nonlinear scalar field Dirac-Born-Infeld action for the unification of dark matter and dark energy using Gamma-Ray Bursts at high-redshifts. We use the sample of 59 high-redshift GRBs reported by Wei (2010), calibrated at low redshifts with the Union 2 sample of SNe Ia, thus avoiding the circularity problem. In this analysis, we also include the CMB7-year data and the baryonic acoustic peak BAO. Besides, it is calculated the parameter of the equation of state $w$, the deceleration parameter $q_0$ and the redshift of the transition to the decelerate-accelerated phase $z_t$.

  14. Space-time curvature due to quantum vacuum fluctuations: An alternative to dark energy?

    E-Print Network [OSTI]

    Santos, Emilio

    2010-01-01

    It is pointed out that quantum vacuum fluctuations may give rise to a curvature of space-time equivalent to the curvature currently attributed to dark energy. A simple calculation is made, which suggests that the value of the dark energy density is roughly given by the product of Newton constant time the quantity m^6 c^4 h^-4, m being a typical mass of elementary particles. The estimate is compatible with observations.

  15. Space-time curvature due to quantum vacuum fluctuations: An alternative to dark energy?

    E-Print Network [OSTI]

    Emilio Santos

    2009-12-30

    It is pointed out that quantum vacuum fluctuations may give rise to a curvature of space-time equivalent to the curvature currently attributed to dark energy. A simple calculation is made, which suggests that the value of the dark energy density is roughly given by the product of Newton constant time the quantity m^6 c^4 h^-4, m being a typical mass of elementary particles. The estimate is compatible with observations.

  16. Testing models of vacuum energy interacting with cold dark matter

    E-Print Network [OSTI]

    Li, Yun-He; Zhang, Xin

    2015-01-01

    We test the models of vacuum energy interacting with cold dark matter, and try to probe the possible deviation from the $\\Lambda$CDM model using current observations. We focus on two specific models, $Q=3\\beta H\\rho_{\\Lambda}$ and $Q=3\\beta H\\rho_c$. The data combinations come from the Planck 2013 data, the baryon acoustic oscillations measurements, the Type-Ia supernovae data, the Hubble constant measurement, the redshift space distortions data and the galaxy weak lensing data. For the $Q=3\\beta H\\rho_c$ model, we find that it can be tightly constrained by all the data combinations, while for the $Q=3\\beta H\\rho_{\\Lambda}$ model there still exist significant degeneracies between parameters. The tightest constraints for the coupling constant are $\\beta=-0.026^{+0.036}_{-0.053}$ (for $Q=3\\beta H\\rho_{\\Lambda}$) and $\\beta=-0.00045\\pm0.00069$ (for $Q=3\\beta H\\rho_c$) at $1\\sigma$ level. For all the fit results, we find that the null interaction $\\beta=0$ is always consistent with data. Our work completes the di...

  17. Utility of observational Hubble parameter data on dark energy evolution

    E-Print Network [OSTI]

    Meng, Xiao-Lei; Li, Shi-Yu; Zhang, Tong-Jie

    2015-01-01

    Aiming at exploring the nature of dark energy, we use thirty-six observational Hubble parameter data (OHD) in the redshift range $0 \\leqslant z \\leqslant 2.36$ to make a cosmological model-independent test of the two-point $Omh^2(z_{2};z_{1})$ diagnostic. In $\\Lambda$CDM, we have $Omh^2 \\equiv \\Omega_{m}h^2$, where $\\Omega_{m}$ is the matter density parameter at present. We bin all the OHD into four data points to mitigate the observational contaminations. By comparing with the value of $\\Omega_{m}h^2$ which is constrained tightly by the Planck observations, our results show that in all six testing pairs of $Omh^2$ there are two testing pairs are consistent with $\\Lambda$CDM at $1\\sigma$ confidence level (CL), whereas for another two of them $\\Lambda$CDM can only be accommodated at $2\\sigma$ CL. Particularly, for remaining two pairs, $\\Lambda$CDM is not compatible even at $2\\sigma$ CL. Therefore it is reasonable that although deviations from $\\Lambda$CDM exist for some pairs, cautiously, we cannot rule out th...

  18. New Camera Sheds Light on Dark Energy | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirley Ann JacksonDepartment of Energy FacilitiesCleantechthe openControllingDr. SaulManyZoomed-in

  19. arXiv:1004.0236v1[astro-ph.CO]1Apr2010 Figures of merit for present and future dark energy probes

    E-Print Network [OSTI]

    Hu, Wayne

    arXiv:1004.0236v1[astro-ph.CO]1Apr2010 Figures of merit for present and future dark energy probes constraints on dynamical dark energy models from Type Ia supernovae and the cosmic microwave background using figures of merit based on the volume of the allowed dark energy parameter space. For a two-parameter dark

  20. A Boiler Plant Energy Efficiency and Load Balancing Survey 

    E-Print Network [OSTI]

    Nutter, D. W.; Murphy, D. R.

    1997-01-01

    Daily energy use data was used to perform an energy efficiency survey of a medium-sized university boiler plant. The physical plant operates centralized mechanical plants to provide both chilled water and steam for building conditioning. Steam...

  1. Cool Trends in District Energy: A Survey of Thermal Energy Storage Use in District Energy Utility Applications, June 2005

    Broader source: Energy.gov [DOE]

    A Survey of Thermal Energy Storage (TES) Use In District Energy (DE) Utility Applications in June 2005

  2. Dynamical 3-Space: Supernovae and the Hubble Expansion - Older Universe and End of Dark Energy

    E-Print Network [OSTI]

    Reginald T Cahill

    2007-06-05

    We apply the new dynamics of 3-space to cosmology by deriving a Hubble expansion solution. This dynamics involves two constants; G and alpha - the fine structure constant. This solution gives an excellent parameter-free fit to the recent supernova and gamma-ray burst data without the need for `dark energy' or `dark matter'. The data and theory together imply an older age for the universe of some 14.7Gyrs. Various problems such as fine tuning, the event horizon problem etc are now resolved. A brief review discusses the origin of the 3-space dynamics and how that dynamics explained the bore hole anomaly, spiral galaxy flat rotation speeds, the masses of black holes in spherical galaxies, gravitational light bending and lensing, all without invoking `dark matter' or `dark energy'. These developments imply that a new understanding of the universe is now available.

  3. Ultra low energy results and their impact to dark matter and low energy neutrino physics

    E-Print Network [OSTI]

    E. Bougamont; P. Colas; J. Derre; I. Giomataris; G. Gerbier; M. Gros; P. Magnier; X. F. Navick; P. Salin; I. Savvidis; G. Tsiledakis; J. D. Vergados

    2010-10-20

    We present ultra low energy results taken with the novel Spherical Proportional Counter. The energy threshold has been pushed down to about 25 eV and single electrons are clearly collected and detected. To reach such performance low energy calibration systems have been successfully developed: - A pulsed UV lamp extracting photoelectrons from the inner surface of the detector - Various radioactive sources allowing low energy peaks through fluorescence processes. The bench mark result is the observation of a well resolved peak at 270 eV due to carbon fluorescence which is unique performance for such large-massive detector. It opens a new window in dark matter and low energy neutrino search and may allow detection of neutrinos from a nuclear reactor or from supernova via neutrino-nucleus elastic scattering

  4. 2007 Survey of Energy Resources World Energy Council 2007 Wave Energy COUNTRY NOTES

    E-Print Network [OSTI]

    2007 Survey of Energy Resources World Energy Council 2007 Wave Energy 550 COUNTRY NOTES The following Country Notes on Wave Energy have been compiled by Tom Thorpe and the Editors. Every effort has been made to be comprehensive by making contact with all known wave energy developers. However

  5. Observational constraints on a Yang-Mills condensate dark energy model

    E-Print Network [OSTI]

    Z. W. Fu; Y. Zhang; M. L. Tong

    2011-10-25

    Using the recently released Union2 compilation with 557 Type Ia supernovae, the shift parameter of cosmic microwave background given by the WMAP7 observations, and the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, we perform the $\\chi^2$ analysis on the 1-loop Yang-Mills condensate (YMC) dark energy model. The analysis has been made for both non-coupling and coupling models with $\\Omega_{m0}$ and $w_0$ being treated as free parameters. It is found that, $\\chi^2_{min}$ = 542.870 at $\\Omega_{m0}$ = 0.2701 and $w_0$ = -0.9945 for non-coupling model, and $\\chi^2_{min}$ = 542.790 at $\\gamma$ = -0.015, $\\Omega_{m0}$ = 0.2715 and $w_0$ = -0.9969 for coupling model. Comparing with the $\\Lambda$CDM model, the YMC model has a smaller $\\chi^2_{min}$, but it has greater values of the Bayesian and Akaike information criteria. Overall, YMC is as robust as $\\Lambda$CDM.

  6. Environmental Survey preliminary report, Solar Energy Research Institute, Golden, Colorado

    SciTech Connect (OSTI)

    Not Available

    1988-10-01

    This report presents the preliminary findings of the first phase of the Environmental Survey of the US Department of Energy's (DOE) Solar Energy Research Institute (SERI), conducted December 14 through 18, 1987. The Survey is being conducted by an interdisciplinary team of environmental specialists, led and managed by the Office of Environment, Safety and Health's Office of Environmental Audit. The team includes outside experts supplied by private contractors. The objective of the Survey is to identify environmental problems and areas of environmental risk associated with SERI. The Survey covers all environmental media and all areas of environmental regulation. It is being performed in accordance with the DOE Environmental Survey Manual. The on-site phase of the Survey involves the review of existing site environmental data, observations of the operations carried on at SERI, and interviews with site personnel. 33 refs., 22 figs., 21 tabs.

  7. Some Consequences of Dark Energy Density varying Exponentially with Scale Factor

    E-Print Network [OSTI]

    Sanil Unnikrishnan; T. R. Seshadri

    2005-11-10

    In this paper we have explored the consequences of a model of dark energy with its energy density varying exponentially with the scale factor. We first consider the model with $ \\rho_{\\phi} \\propto e^{\\kappa a} $, where $\\kappa $ is a constant. This is a kind of generalisation of the cosmological constant model with $\\kappa = 0$. We show that such an exponentially varying dark energy density with the scale factor naturally leads to an equivalent phantom field. We also consider a model with $ \\rho_{\\phi} \\propto e^{\\kappa /a} $ and we show that this also naturally leads to an equivalent phantom field.

  8. High-energy neutrino signals from the Sun in dark matter scenarios with internal bremsstrahlung

    SciTech Connect (OSTI)

    Ibarra, Alejandro; Totzauer, Maximilian; Wild, Sebastian E-mail: maximilian.totzauer@mytum.de

    2013-12-01

    We investigate the prospects to observe a high energy neutrino signal from dark matter annihilations in the Sun in scenarios where the dark matter is a Majorana fermion that couples to a quark and a colored scalar via a Yukawa coupling. In this minimal scenario, the dark matter capture and annihilation in the Sun can be studied in a single framework. We find that, for small and moderate mass splitting between the dark matter and the colored scalar, the two-to-three annihilation q q-bar g plays a central role in the calculation of the number of captured dark matter particles. On the other hand, the two-to-three annihilation into q q-bar Z gives, despite its small branching fraction, the largest contribution to the neutrino flux at the Earth at the highest energies. We calculate the limits on the model parameters using IceCube observations of the Sun and we discuss their interplay with the requirement of equilibrium of captures and annihilations in the Sun and with the requirement of thermal dark matter production. We also compare the limits from IceCube to the limits from direct detection, antiproton measurements and collider searches.

  9. Modelling Herschel observations of infrared-dark clouds in the Hi-GAL survey

    E-Print Network [OSTI]

    Stamatellos, D; Kirk, J; Molinari, S; Sibthorpe, B; Ward-Thompson, D; Whitworth, A; Wilcock, L

    2010-01-01

    We demonstrate the use of the 3D Monte Carlo radiative transfer code PHAETHON to model infrared-dark clouds (IRDCs) that are externally illuminated by the interstellar radiation field (ISRF). These clouds are believed to be the earliest observed phase of high-mass star formation, and may be the high-mass equivalent of lower-mass prestellar cores. We model three different cases as examples of the use of the code, in which we vary the mass, density, radius, morphology and internal velocity field of the IRDC. We show the predicted output of the models at different wavelengths chosen to match the observing wavebands of Herschel and Spitzer. For the wavebands of the long- wavelength SPIRE photometer on Herschel, we also pass the model output through the SPIRE simulator to generate output images that are as close as possible to the ones that would be seen using SPIRE. We then analyse the images as if they were real observations, and compare the results of this analysis with the results of the radiative transfer mod...

  10. Thermodynamical description of modified generalized Chaplygin gas model of dark energy

    E-Print Network [OSTI]

    H. Ebadi; H. Moradpour

    2015-04-15

    We consider a universe filled by a modified generalized Chaplygin gas together with a pressureless dark matter component. We get a thermodynamical interpretation for the modified generalized Chaplygin gas confined to the apparent horizon of FRW universe, whiles dark sectors do not interact with each other. Thereinafter, by taking into account a mutual interaction between the dark sectors of the cosmos, we find a thermodynamical interpretation for interacting modified generalized Chaplygin gas. Additionally, probable relation between the thermal fluctuations of the system and the assumed mutual interaction is investigated. Finally, we show that if one wants to solve the coincidence problem by using this mutual interaction, then the coupling constants of the interaction will be constrained. The corresponding constraint is also addressed. Moreover, the thermodynamic interpretation of using either a generalized Chaplygin gas or a Chaplygin gas to describe dark energy is also addressed throughout the paper.

  11. High Energy Electron Signals from Dark Matter Annihilation in the Sun

    SciTech Connect (OSTI)

    Schuster, Philip; Toro, Natalia; Weiner, Neal; Yavin, Itay; /New York U., CCPP

    2012-04-09

    In this paper we discuss two mechanisms by which high energy electrons resulting from dark matter annihilations in or near the Sun can arrive at the Earth. Specifically, electrons can escape the sun if DM annihilates into long-lived states, or if dark matter scatters inelastically, which would leave a halo of dark matter outside of the sun. Such a localized source of electrons may affect the spectra observed by experiments with narrower fields of view oriented towards the sun, such as ATIC, differently from those with larger fields of view such as Fermi. We suggest a simple test of these possibilities with existing Fermi data that is more sensitive than limits from final state radiation. If observed, such a signal will constitute an unequivocal signature of dark matter.

  12. Constraining Dark Energy and Cosmological Transition Redshift with Type Ia Supernovae

    E-Print Network [OSTI]

    F. Y. Wang; Z. G. Dai

    2007-08-30

    The property of dark energy and the physical reason for acceleration of the present universe are two of the most difficult problems in modern cosmology. The dark energy contributes about two-thirds of the critical density of the present universe from the observations of type-Ia supernova (SNe Ia) and anisotropy of cosmic microwave background (CMB).The SN Ia observations also suggest that the universe expanded from a deceleration to an acceleration phase at some redshift, implying the existence of a nearly uniform component of dark energy with negative pressure. We use the ``gold'' sample containing 157 SNe Ia and two recent well-measured additions, SNe Ia 1994ae and 1998aq to explore the properties of dark energy and the transition redshift. For a flat universe with the cosmological constant, we measure $\\Omega_{M}=0.28_{-0.05}^{+0.04}$, which is consistent with Riess et al. The transition redshift is $z_{T}=0.60_{-0.08}^{+0.06}$. We also discuss several dark energy models that define the $w(z)$ of the parameterized equation of state of dark energy including one parameter and two parameters ($w(z)$ being the ratio of the pressure to energy density). Our calculations show that the accurately calculated transition redshift varies from $z_{T}=0.29_{-0.06}^{+0.07}$ to $z_{T}=0.60_{-0.08}^{+0.06}$ across these models. We also calculate the minimum redshift $z_{c}$ at which the current observations need the universe to accelerate.

  13. Quantifying the impact of future Sandage-Loeb test data on dark energy constraints

    SciTech Connect (OSTI)

    Geng, Jia-Jia; Zhang, Jing-Fei; Zhang, Xin E-mail: jfzhang@mail.neu.edu.cn

    2014-07-01

    The Sandage-Loeb (SL) test is a unique method to probe dark energy in the ''redshift desert'' of 2?dark energy probes. Therefore, it is of great importance to quantify how the future SL test data impact on the dark energy constraints. To avoid the potential inconsistency in data, we use the best-fitting model based on the other geometric measurements as the fiducial model to produce 30 mock SL test data. The 10-yr, 20-yr, and 30-yr observations of SL test are analyzed and compared in detail. We show that compared to the current combined data of type Ia supernovae, baryon acoustic oscillation, cosmic microwave background, and Hubble constant, the 30-yr observation of SL test could improve the constraint on ?{sub m} by about 80% and the constraint on w by about 25%. Furthermore, the SL test can also improve the measurement of the possible direct interaction between dark energy and dark matter. We show that the SL test 30-yr data could improve the constraint on ? by about 30% and 10% for the Q = ?H?{sub c} and Q = ?H?{sub de} models, respectively.

  14. Physical approximations for the nonlinear evolution of perturbations in dark energy scenarios

    E-Print Network [OSTI]

    L. R. Abramo; R. C. Batista; L. Liberato; R. Rosenfeld

    2008-06-20

    The abundance and distribution of collapsed objects such as galaxy clusters will become an important tool to investigate the nature of dark energy and dark matter. Number counts of very massive objects are sensitive not only to the equation of state of dark energy, which parametrizes the smooth component of its pressure, but also to the sound speed of dark energy as well, which determines the amount of pressure in inhomogeneous and collapsed structures. Since the evolution of these structures must be followed well into the nonlinear regime, and a fully relativistic framework for this regime does not exist yet, we compare two approximate schemes: the widely used spherical collapse model, and the pseudo-Newtonian approach. We show that both approximation schemes convey identical equations for the density contrast, when the pressure perturbation of dark energy is parametrized in terms of an effective sound speed. We also make a comparison of these approximate approaches to general relativity in the linearized regime, which lends some support to the approximations.

  15. Physical approximations for the nonlinear evolution of perturbations in inhomogeneous dark energy scenarios

    SciTech Connect (OSTI)

    Abramo, L. R.; Batista, R. C. [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05315-970, Sao Paulo (Brazil); Liberato, L.; Rosenfeld, R. [Instituto de Fisica Teorica, Universidade Estadual Paulista, R. Pamplona 145, 01405-900, Sao Paulo (Brazil)

    2009-01-15

    The abundance and distribution of collapsed objects such as galaxy clusters will become an important tool to investigate the nature of dark energy and dark matter. Number counts of very massive objects are sensitive not only to the equation of state of dark energy, which parametrizes the smooth component of its pressure, but also to the sound speed of dark energy, which determines the amount of pressure in inhomogeneous and collapsed structures. Since the evolution of these structures must be followed well into the nonlinear regime, and a fully relativistic framework for this regime does not exist yet, we compare two approximate schemes: the widely used spherical collapse model and the pseudo-Newtonian approach. We show that both approximation schemes convey identical equations for the density contrast, when the pressure perturbation of dark energy is parametrized in terms of an effective sound speed. We also make a comparison of these approximate approaches to general relativity in the linearized regime, which lends some support to the approximations.

  16. Model-Independent Dark Energy Equation of State from Baryon Acoustic Oscillations

    E-Print Network [OSTI]

    Jarah Evslin

    2015-10-20

    We present a simple formula for the average dark energy equation of state at redshifts between those of two observations of baryon acoustic oscillations (BAO). The formula is independent of any parametrization or basis of the dark energy equation of state and essentially independent of the cosmological model. We use this formula to study the well-known tension between Lyman alpha forest BAO and other cosmological probes. Using only the line of sight Lyman alpha forest BAO and BOSS CMASS dataset, there is already more than 2 sigma tension with the standard LambdaCDM cosmological model which implies that either (i) The BOSS Lyman alpha forest measurement of the Hubble parameter was too low as a result of a statistical fluctuation or systematic error or else (ii) the dark energy equation of state falls steeply at high redshift.

  17. Testing for dynamical dark energy models with redshift-space distortions

    SciTech Connect (OSTI)

    Tsujikawa, Shinji [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Felice, Antonio De [ThEP's CRL, NEP, The Institute for Fundamental Study, Naresuan University, Phitsanulok 65000 (Thailand); Alcaniz, Jailson, E-mail: shinji@rs.kagu.tus.ac.jp, E-mail: antoniod@nu.ac.th, E-mail: alcaniz@on.br [Departamento de Astronomia, Observatório Nacional, 20921-400 Rio de Janeiro - RJ (Brazil)

    2013-01-01

    The red-shift space distortions in the galaxy power spectrum can be used to measure the growth rate of matter density perturbations ?{sub m}. For dynamical dark energy models in General Relativity we provide a convenient analytic formula of f(z)?{sub 8}(z) written as a function of the redshift z, where f = dln ?{sub m}/dln a (a is the cosmological scale factor) and ?{sub 8} is the rms amplitude of over-density at the scale 8 h{sup ?1} Mpc. Our formula can be applied to the models of imperfect fluids, quintessence, and k-essence, provided that the dark energy equation of state w does not vary significantly and that the sound speed is not much smaller than 1. We also place observational constraints on dark energy models of constant w and tracking quintessence from the recent data of red-shift space distortions.

  18. Model-Independent Dark Energy Equation of State from Baryon Acoustic Oscillations

    E-Print Network [OSTI]

    Evslin, Jarah

    2015-01-01

    We present a simple formula for the average dark energy equation of state at redshifts between those of two observations of baryon acoustic oscillations (BAO). The formula is independent of any parametrization or basis of the dark energy equation of state and essentially independent of the cosmological model. We use this formula to study the well-known tension between Lyman alpha forest BAO and other cosmological probes. Using only the line of sight Lyman alpha forest BAO and BOSS CMASS dataset, there is already more than 2 sigma tension with the standard LambdaCDM cosmological model which implies that either (i) The BOSS Lyman alpha forest measurement of the Hubble parameter was too low as a result of a statistical fluctuation or systematic error or else (ii) the dark energy equation of state falls steeply at high redshift.

  19. Similarity dark energy models in Bianchi type -I space-time

    E-Print Network [OSTI]

    Ali, Ahmad T; Alzahrani, Abdulah K

    2015-01-01

    We investigate some new similarity solutions of anisotropic dark energy and perfect fluid in Bianchi type-I space-time. Three different time dependent skewness parameters along the spatial directions are introduced to quantify the deviation of pressure from isotropy. We consider the case when the dark energy is minimally coupled to the perfect fluid as well as direct interaction with it. The Lie symmetry generators that leave the equation invariant are identified and we generate an optimal system of one-dimensional subalgebras. Each element of the optimal system is used to reduce the partial differential equation to an ordinary differential equation which is further analyzed. We solve the Einstein field equations, described by a system of non-linear partial differential equations (NLPDEs), by using the Lie point symmetry analysis method. The geometrical and kinematical features of the models and the behavior of the anisotropy of dark energy, are examined in detail.

  20. Constraining a scalar field dark energy with variable equation of state for matter

    E-Print Network [OSTI]

    A. Sil; S. Som

    2014-12-01

    The red-shift $z_{eq}$, marking the end of radiation era and the beginning of matter-dominated era, can play an important role to reconstruct dark-energy models. A variable equation of state for matter that can bring a smooth transition from radiation to matter-dominated era in a single model is proposed to estimate $z_{eq}$ in dark energy models and hence its viability. Two one-parameter models with minimally coupled scalar fields playing the role of dark energy are chosen to demonstrate this point. It is found that for desired late time behavior of the models, the estimated value of $z_{eq}$ is highly sensitive on the value of the parameter in each of these models.

  1. Local Group dSph radio survey with ATCA (III): constraints on particle dark matter

    SciTech Connect (OSTI)

    Regis, Marco [Dipartimento di Fisica, Università di Torino, via P. Giuria 1, I-10125 Torino (Italy); Colafrancesco, Sergio [School of Physics, University of the Witwatersrand, Johannesburg (South Africa); Profumo, Stefano [Department of Physics, University of California, 1156 High St., Santa Cruz, CA 95064 (United States); De Blok, W.J.G. [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Massardi, Marcella [INAF—Istituto di Radioastronomia, Via Gobetti 101, I-40129, Bologna (Italy); Richter, Laura, E-mail: regis@to.infn.it, E-mail: sergio.colafrancesco@wits.ac.za, E-mail: profumo@ucsc.edu, E-mail: blok@astron.nl, E-mail: massardi@ira.inaf.it, E-mail: laura@ska.ac.za [SKA South Africa, 3rd Floor, The Park, Park Road, Pinelands, 7405 (South Africa)

    2014-10-01

    We performed a deep search for radio synchrotron emissions induced by weakly interacting massive particles (WIMPs) annihilation or decay in six dwarf spheroidal (dSph) galaxies of the Local Group. Observations were conducted with the Australia Telescope Compact Array (ATCA) at 16 cm wavelength, with an rms sensitivity better than 0.05 mJy/beam in each field. In this work, we first discuss the uncertainties associated with the modeling of the expected signal, such as the shape of the dark matter (DM) profile and the dSph magnetic properties. We then investigate the possibility that point-sources detected in the proximity of the dSph optical center might be due to the emission from a DM cuspy profile. No evidence for an extended emission over a size of few arcmin (which is the DM halo size) has been detected. We present the associated bounds on the WIMP parameter space for different annihilation/decay final states and for different astrophysical assumptions. If the confinement of electrons and positrons in the dSph is such that the majority of their power is radiated within the dSph region, we obtain constraints on the WIMP annihilation rate which are well below the thermal value for masses up to few TeV. On the other hand, for conservative assumptions on the dSph magnetic properties, the bounds can be dramatically relaxed. We show however that, within the next 10 years and regardless of the astrophysical assumptions, it will be possible to progressively close in on the full parameter space of WIMPs by searching for radio signals in dSphs with SKA and its precursors.

  2. #LabChat: What is Dark Energy? Oct 25 at 2pm ET | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirley Ann JacksonDepartment| Department of EnergyDataWindofEDT | Department ofWhat is dark

  3. New constraints on dark energy from the observed growth of the most X-ray luminous galaxy clusters

    E-Print Network [OSTI]

    Mantz, A; Ebeling, H; Rapetti, D

    2007-01-01

    We present constraints on the mean matter density, Omega_m, normalization of the density fluctuation power spectrum, sigma_8, and dark energy equation of state parameter, w, obtained from the X-ray luminosity function of the Massive Cluster Survey (MACS) in combination with the local BCS and REFLEX galaxy cluster samples. Our analysis incorporates the mass function predictions of Jenkins et al. (2001), a mass-luminosity relation calibrated using the data of Reiprich and Bohringer (2002), and standard priors on the Hubble constant, H_0, and mean baryon density, Omega_b h^2. We find Omega_m=0.27 +0.06 -0.05 and sigma_8=0.77 +0.07 -0.06 for a spatially flat, cosmological constant model, and Omegam=0.28 +0.08 -0.06, sigma_8=0.75 +- 0.08 and w=-0.97 +0.20 -0.19 for a flat, constant-w model. Our findings constitute the first precise determination of the dark energy equation of state from measurements of the growth of cosmic structure in galaxy clusters. The consistency of our result with w=-1 lends strong additiona...

  4. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01

    1978, High temperature underground thermal energy storage,in Proceedings, Thermal Energy Storage in Aquifers Workshop:High temperature underground thermal energy storage, in ATES

  5. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01

    the prob- lem of seasonal storage of thermal energy (Matheyto study seasonal storage of thermal energy: winter storagewithin the Seasonal Thermal Energy Storage Program managed

  6. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01

    High temperature underground thermal energy storage, inProceedings, Thermal Energy Storage in Aquifers Workshop:underground thermal energy storage, in ATES newsletter:

  7. ORNL/SUB/02-4000008627/01 TRANSPORTATION ENERGY SURVEY

    E-Print Network [OSTI]

    ORNL/SUB/02-4000008627/01 TRANSPORTATION ENERGY SURVEY DATA BOOK 1.1 Tatyana Gurikova Macrosystems-Battelle, LLC for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-00OR22725 #12;ii #12;iii TABLE ................................................................................................................. 1 2. ENERGY, OIL AND POLICY

  8. The DarkLight Experiment: A Precision Search for New Physics at Low Energies

    E-Print Network [OSTI]

    J. Balewski; J. Bernauer; J. Bessuille; R. Corliss; R. Cowan; C. Epstein; P. Fisher; D. Hasell; E. Ihloff; Y. Kahn; J. Kelsey; R. Milner; S. Steadman; J. Thaler; C. Tschalaer; C. Vidal; S. Benson; J. Boyce; D. Douglas; P. Evtushenko; C. Hernandez-Garcia; C. Keith; C. Tennant; S. Zhang; R. Alarcon; D. Blyth; R. Dipert; L. Ice; G. Randall; B. Dongwi; N. Kalantarians; M. Kohl; A. Liyanage; J. Nazeer; M. Garcon; R. Cervantes; K. Dehmelt; A. Deshpande; N. Feege; B. Surrow

    2014-12-15

    We describe the current status of the DarkLight experiment at Jefferson Laboratory. DarkLight is motivated by the possibility that a dark photon in the mass range 10 to 100 MeV/c$^2$ could couple the dark sector to the Standard Model. DarkLight will precisely measure electron proton scattering using the 100 MeV electron beam of intensity 5 mA at the Jefferson Laboratory energy recovering linac incident on a windowless gas target of molecular hydrogen. The complete final state including scattered electron, recoil proton, and e+e- pair will be detected. A phase-I experiment has been funded and is expected to take data in the next eighteen months. The complete phase-II experiment is under final design and could run within two years after phase-I is completed. The DarkLight experiment drives development of new technology for beam, target, and detector and provides a new means to carry out electron scattering experiments at low momentum transfers.

  9. Reducing Zero-point Systematics in Dark Energy Supernova Experiments

    E-Print Network [OSTI]

    Faccioli, Lorenzo

    2011-01-01

    Schmidt, B . P. 2003, i n Supernovae a n d G a m m a - R a ynumber of observed supernovae, m a x i m u m surveyObservations of type l a Supernovae (SNe la) have allowed

  10. Observational constraints on dark energy with a fast varying equation of state

    SciTech Connect (OSTI)

    Felice, Antonio De; Nesseris, Savvas

    2012-05-01

    We place observational constraints on models with the late-time cosmic acceleration based on a number of parametrizations allowing fast transitions for the equation of state of dark energy. In addition to the model of Linder and Huterer where the dark energy equation of state w monotonically grows or decreases in time, we propose two new parametrizations in which w has an extremum. We carry out the likelihood analysis with the three parametrizations by using the observational data of supernovae type Ia, cosmic microwave background, and baryon acoustic oscillations. Although the transient cosmic acceleration models with fast transitions can give rise to the total chi square smaller than that in the ?-Cold-Dark-Matter (?CDM) model, these models are not favored over ?CDM when one uses the Akaike information criterion which penalizes the extra degrees of freedom present in the parametrizations.

  11. Gravastars with an Interior Dark Energy Fluid Forming a Naked Singularity

    E-Print Network [OSTI]

    C. F. C. Brandt; R. Chan; M. F. A. da Silva; P. Rocha

    2011-12-21

    We consider a gravastar model made of anisotropic dark energy with an infinitely thin spherical shell of a perfect fluid with the equation of state $p = (1-\\gamma)\\sigma$ with an external de Sitter-Schwarzschild region. It is found that in some cases the models represent the "bounded excursion" stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes or naked singularities. An interesting result is that we can have black hole and stable gravastar formation even with an interior and a shell cons tituted of dark and repulsive dark energy, as also shown in previous work. Besides, in one case we have a dynamical evolution to a black hole (for $\\Lambda =0$) or to a naked singularity (for $\\Lambda > 0$). This is the first time in the literature that a naked singularity emerges from a gravastar model.

  12. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01

    Institut de Production d 1 Energie 6 Centre d'Hydrolgeologiebei einer Ruckgewinnung der Energie (Practical ways of heatInstitut de Production d 1 Energie 6 Centre d Hydrog~ologie

  13. Examining Sustainable Development Policy in California Cities: 2011 Energy Sustainable California Communities Survey

    E-Print Network [OSTI]

    Kwon, Myungjung

    2013-01-01

    Energy Sustainable California Communities Survey, Interna- tional County/City Management Association (ICMA), and US

  14. Hydro-Gravitational-Dynamics of Planets and Dark Energy

    E-Print Network [OSTI]

    Gibson, Carl H

    2008-01-01

    Self-gravitational fluid mechanical methods termed hydro-gravitational-dynamics (HGD) predict plasma fragmentation 0.03 Myr after the turbulent big bang to form protosuperclustervoids, turbulent protosuperclusters, and protogalaxies at the 0.3 Myr transition from plasma to gas. Linear protogalaxyclusters fragment at 0.003 Mpc viscous-inertial scales along turbulent vortex lines or in spirals, as observed. The plasma protogalaxies fragment on transition into white-hot planet-mass gas clouds (PFPs) in million-solar-mass clumps (PGCs) that become globular-star-clusters (GCs) from tidal forces or dark matter (PGCs) by freezing and diffusion into 0.3 Mpc halos with 97% of the galaxy mass. The weakly collisional non-baryonic dark matter diffuses to > Mpc scales and frag-ments to form galaxy cluster halos. Stars and larger planets form by binary mergers of the trillion PFPs per PGC on 0.03 Mpc galaxy accretion disks. Star deaths depend on rates of planet accretion and internal star mixing. Moderate accretion rates p...

  15. Low Energy Nuclear Recoil Response in Xenon Gas for Low Mass Dark Matter WIMP Search 

    E-Print Network [OSTI]

    Sofka, Clement James

    2014-04-16

    these "dark" sources of matter/energy is the single most important concern in the modern quest for understanding Nature. We live in an epoch that is almost certainly characterized by a at, expanding Universe. Coupling this with the wealth of astrophysical...

  16. Modified Hubble law, the time-varying Hubble parameter and the problem of dark energy

    E-Print Network [OSTI]

    Jian-Miin Liu

    2005-11-14

    In the framework of the solvable model of cosmology constructed in the Earth-related coordinate system, we derive the modified Hubble law. This law carries the slowly time-varying Hubble parameter. The modified Hubble law eliminates the need for dark energy.

  17. The role of potential in the ghost-condensate dark energy model

    E-Print Network [OSTI]

    Gour Bhattacharya; Pradip Mukherjee; Anirban Saha; Amit Singha Roy

    2014-12-15

    We consider the ghost-condensate model of dark energy with a generic potential term. The inclusion of the potential is shown to give greater freedom in realising the phantom regime. The self-consistency of the analysis is demonstrated using WMAP7+BAO+Hubble data.

  18. arXiv:0908.1408v1[astro-ph.CO]10Aug2009 Hiding dark energy transitions at low redshift

    E-Print Network [OSTI]

    Hu, Wayne

    arXiv:0908.1408v1[astro-ph.CO]10Aug2009 Hiding dark energy transitions at low redshift Michael history. Interestingly, the other place where an order unity transition in the dark energy equation requirements on dark energy, and construct explicit scalar field models of the transition. We discuss

  19. Survey of Household Energy Use (SHEU)

    E-Print Network [OSTI]

    and 1997. Its goal is to gather data on the energy and physical characteristics of private dwellings to number of dwellings, dwelling area, energy consumption and energy intensity. The target population. The number of dwellings is expressed in units; energy consumption, in gigajoules (GJ); heated area, in square

  20. Power-Law and Logarithmic Entropy-Corrected Ricci Viscous Dark Energy and Dynamics of Scalar Fields

    E-Print Network [OSTI]

    Antonio Pasqua

    2013-03-12

    In this work, I consider the logarithmic-corrected and the power-law corrected versions of the holographic dark energy (HDE) model in the non-flat FRW universe filled with a viscous Dark Energy (DE) interacting with Dark Matter (DM). We propose to replace the infra-red cut-off with the inverse of the Ricci scalar curvature $R$. I obtain the equation of state (EoS) parameter $\\omega_{\\Lambda}$, the deceleration parameter $q$ and the evolution of energy density parameter $\\Omega_D'$ in the presence of interaction between DE and DM for both corrections. I study the correspondence of the logarithmic entropy corrected Ricci Dark Dnergy (LECRDE) and power-law entropy corrected Ricci Dark Energy (PLECRDE) models with the the Modified Chaplygin Gas (MCG) and some scalar fields including tachyon, K-essence, dilaton and quintessence. I also make comparisons with previous results.

  1. Generalised second law of thermodynamics for interacting dark energy in the DGP brane world

    E-Print Network [OSTI]

    Jibitesh Dutta; Subenoy Chakraborty

    2010-06-11

    In this paper, we investigate the validity of the generalized second law of thermodynamics (GSLT) in the DGP brane world when universe is filled with interacting two fluid system: one in the form of cold dark matter and other is holographic dark energy. The boundary of the universe is assumed to be enclosed by the dynamical apparent horizon or the event horizon. The universe is chosen to be homogeneous and isotropic FRW model and the validity of the first law has been assumed here.

  2. Cosmology in presence of dark energy in an emergent gravity scenario

    E-Print Network [OSTI]

    Debashis Gangopadhyay; Goutam Manna

    2015-02-22

    We obtain the analogues of the Friedman equations in an emergent gravity scenario in the presence of dark energy. The background metric is taken to be Friedman-Lemaitre-Robertson-Walker (FLRW). We show that if $\\dot\\phi ^{2}$ is the dark energy density (in units of the critical density) then (a) for total energy density greater than the pressure (non-relativistic scenario, matter domination) the deceleration parameter $q(t)\\approx\\frac {1}{2} [1 + 27 \\dot\\phi ^{2}+...] > \\frac{1}{2}$ (b) for total energy density equal to 3 times the pressure (relativistic case, radiation domination), the deceleration parameter $q(t)\\approx 1 + 18\\dot\\phi ^{2} +... > 1$ and (c) for total energy density equal to the negative of the pressure (dark energy scenario), the deceleration parameter $q(t)energy right from the beginning of the universe where the time parameter $t\\equiv \\frac{t}{t_{0}}$, $t_{0}$ being the present epoch.

  3. Sample design for the residential energy consumption survey

    SciTech Connect (OSTI)

    Not Available

    1994-08-01

    The purpose of this report is to provide detailed information about the multistage area-probability sample design used for the Residential Energy Consumption Survey (RECS). It is intended as a technical report, for use by statisticians, to better understand the theory and procedures followed in the creation of the RECS sample frame. For a more cursory overview of the RECS sample design, refer to the appendix entitled ``How the Survey was Conducted,`` which is included in the statistical reports produced for each RECS survey year.

  4. Bibliographic survey of medium energy inclusive reaction data

    SciTech Connect (OSTI)

    Arthur, E.D.; Madland, D.G.; McClellan, D.M.

    1986-04-01

    A bibliographic survey of inclusive reaction data (experimental and theoretical) for several projectile types having energies between 50 and 1000 MeV has been completed. Approximately one thousand references selected from this survey describe the current state of knowledge for particle-induced inclusive reaction data. The search covered data for the following projectiles: p, d, t, /sup 3/He, /sup 4/He, and lithium ions.

  5. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01

    aquifers for heat storage, solar captors for heat productionZakhidov, R. A. 8 1971, Storage of solar energy in a sandy-thermal energy storage for cogeneration and solar systems,

  6. Testing the "Dark-Energy"-Dominated Cosmology via the Solar-System Experiments

    E-Print Network [OSTI]

    Yu. V. Dumin

    2006-10-08

    The effect of "dark energy" (i.e. the Lambda-term in Einstein equations) is sought for at the interplanetary scales by comparing the rates of secular increase in the lunar orbit obtained by two different ways: (1) measured immediately by the laser ranging and (2) estimated independently from the deceleration of the Earth's proper rotation. The first quantity involves both the well-known effect of geophysical tides and the Kottler effect of Lambda-term (i.e. a kind of the "local" Hubble expansion), while the second quantity is associated only with the tidal influence. The difference between them, 2.2 +/- 0.3 cm/yr, can be attributed just to the local Hubble expansion with rate H_0^(loc) = 56 +/- 8 km/s/Mpc. Assuming that Hubble expansion is formed locally only by the uniformly distributed dark energy (Lambda-term), while globally also by a clumped substance (for the most part, the cold dark matter), the total (large-scale) Hubble constant should be H_0 = 65 +/- 9 km/s/Mpc. This is in reasonable agreement both with the commonly-accepted WMAP result, H_0 = 71 +/- 3.5 km/s/Mpc, and with the data on supernovae Ia distribution. The above coincidence can serve as one more argument in favor of the dark energy.

  7. Cores in Infra-Red Dark Clouds (IRDCs) seen in the Hi-GAL survey between l = 300{\\deg} and l = 330{\\deg}

    E-Print Network [OSTI]

    Wilcock, L A; Kirk, J M; Stamatellos, D; Whitworth, A; Elia, D; Fuller, G A; DiGiorgio, A; Griffin, M J; Molinari, S; Martin, P; Mottram, J C; Peretto, N; Pestalozzi, M; Schisano, E; Plume, R; Smith, H A; Thompson, M A

    2012-01-01

    We have used data taken as part of the Herschel infrared Galactic Plane survey (Hi-GAL) to study 3171 infrared-dark cloud (IRDC) candidates that were identified in the mid-infrared (8 {\\mu}m) by Spitzer (we refer to these as 'Spitzer-dark' regions). They all lie in the range l=300 - 330 \\circ and |b| 6 1 \\circ. Of these, only 1205 were seen in emission in the far-infrared (250-500 {\\mu}m) by Herschel (we call these 'Herschel-bright' clouds). It is predicted that a dense cloud will not only be seen in absorption in the mid-infrared, but will also be seen in emission in the far-infrared at the longest Herschel wavebands (250-500 {\\mu}m). If a region is dark at all wavelengths throughout the mid-infrared and far-infrared, then it is most likely to be simply a region of lower background infrared emission (a 'hole in the sky'). Hence, it appears that previous surveys, based on Spitzer and other mid-infrared data alone, may have over-estimated the total IRDC population by a factor of 2. This has implications for es...

  8. The Joint Efficient Dark-energy Investigation (JEDI): Measuring the cosmic expansion history from type Ia supernovae

    E-Print Network [OSTI]

    M. M. Phillips; Peter Garnavich; Yun Wang; David Branch; Edward Baron; Arlin Crotts; J. Craig Wheeler; Edward Cheng; Mario Hamuy; for the JEDI Team

    2006-06-28

    JEDI (Joint Efficient Dark-energy Investigation) is a candidate implementation of the NASA-DOE Joint Dark Energy Mission (JDEM). JEDI will probe dark energy in three independent methods: (1) type Ia supernovae, (2) baryon acoustic oscillations, and (3) weak gravitational lensing. In an accompanying paper, an overall summary of the JEDI mission is given. In this paper, we present further details of the supernova component of JEDI. To derive model-independent constraints on dark energy, it is important to precisely measure the cosmic expansion history, H(z), in continuous redshift bins from z \\~ 0-2 (the redshift range in which dark energy is important). SNe Ia at z > 1 are not readily accessible from the ground because the bulk of their light has shifted into the near-infrared where the sky background is overwhelming; hence a space mission is required to probe dark energy using SNe. Because of its unique near-infrared wavelength coverage (0.8-4.2 microns), JEDI has the advantage of observing SNe Ia in the rest frame J band for the entire redshift range of 0 operations, spectra and light curves will be obtained for ~4,000 SNe Ia at z < 2. The resulting constraints on dark energy are discussed, with special emphasis on the improved precision afforded by the rest frame near-infrared data.

  9. Will there be again a transition from acceleration to deceleration in course of the dark energy evolution of the universe?

    E-Print Network [OSTI]

    Supriya Pan; Subenoy Chakraborty

    2013-09-28

    In this work we consider the evolution of the interactive dark fluids in the background of homogeneous and isotropic FRW model of the universe. The dark fluids consist of a warm dark matter and a dark energy and both are described as perfect fluid with barotropic equation of state. The dark species interact non-gravitationally through an additional term in the energy conservation equations. An autonomous system is formed in the energy density spaces and fixed points are analyzed. A general expression for the deceleration parameter has been obtained and it is possible to have more than one zero of the deceleration parameter. Finally, vanishing of the deceleration parameter has been examined with some examples.

  10. Category:Reflection Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmentalBowerbank,CammackFLIR Jump to:RAPID Roadmap Contact Properties JumpReflection Survey

  11. Category:Telluric Survey | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmentalBowerbank,CammackFLIR Jump to:RAPID Roadmap ContactRockEuropeTelluric Survey Jump to:

  12. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01

    energy storage for cogeneration and solar systems, inTwin City district cogeneration system, in Proceedings,proposed system, based on cogeneration of power and heat by

  13. Determination of Dark Energy and Dark Matter from the values of Redshift for the present time, Planck and Trans-Planck epochs of the Big-Bang model

    E-Print Network [OSTI]

    Asger G. Gasanalizade; Ramin A. Hasanalizade

    2015-02-20

    As an alternative to the Standard cosmology model we have developed a new modified Freundlich's (quantum relativity) redshift (MFRS) mechanisms, which provide a precise solutions of the Dark Energy and Dark Matter problems. We apply the joint solution of three MFRS equations for concordances quantize bounce Planck hierarchy steps. Simultaneous scaling solutions of MFRS equations in logarithmic scale appropriate to three cosmological epoch's, yields a currently testable predictions regarding the Dark Matter {\\Omega}_{DM} = 0.25, and Dark Energy {\\Omega}_{DE} = 0.75. These predictions coincides with the recent observational data from WMAP and other a key supernovae SNe Ia findings. Thus, the presence of Dark Matter and Dark Energy had already been not only detected observationally, but also confirmed theoretically with the very compelling accuracy. From the WMAP7 and our predicted ages we find a value of the Hubble constant H_0 = 65.6 km * s^{-1} Mpc^{-1} which is excellent agreement with the Planck 2013 results XVI. Compared with the "holographic scenario" results, we find an important coincidence between our new and "holographic" parameters. We discuss the connection hierarchy between the multiverse masses and examine the status of the cosmic acceleration. The product of the age of the Universe into the cosmic acceleration in each cosmological epochs --including present day are constant and precisely corresponds to an possible observable-geophysical parameter g_U = 9.50005264_{265} (exact) * (m/s^2). For the derived by WMAP7 age of the Universe t_{W7} = 13.75(13) * 10^9 yr, we find the relevant acceleration a_{W7} = 6.91(65) * 10^{-10} m/s^2. The predicted value of t_0 = 9.0264_9(51) * 10^2 Gyr is consistent with the background acceleration. a_0 = 1.05246_4(61) * 10^{-11} m/s^2.

  14. Cool Trends on Campus: A Survey of Thermal Energy Storage Use...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    on Campus: A Survey of Thermal Energy Storage Use in Campus District Energy Systems, May 2005 Cool Trends on Campus: A Survey of Thermal Energy Storage Use in Campus District...

  15. Yang-Mills condensate dark energy coupled with matter and radiation

    E-Print Network [OSTI]

    Y. Zhang; T. Y. Xia; W. Zhao

    2006-09-26

    The coincidence problem is studied for the dark energy model of effective Yang-Mills condensate in a flat expanding universe during the matter-dominated stage. The YMC energy $\\rho_y(t)$ is taken to represent the dark energy, which is coupled either with the matter, or with both the matter and the radiation components. The effective YM Lagrangian is completely determined by quantum field theory up to 1-loop order. It is found that under very generic initial conditions and for a variety of forms of coupling, the existence of the scaling solution during the early stages and the subsequent exit from the scaling regime are inevitable. The transition to the accelerating stage always occurs around a redshift $z\\simeq (0.3\\sim 0.5)$. Moreover, when the Yang-Mills condensate transfers energy into matter or into both matter and radiation, the equation of state $w_y$ of the Yang-Mills condensate can cross over -1 around $z\\sim 2$, and takes on a current value $\\simeq -1.1$. This is consistent with the recent preliminary observations on supernovae Ia. Therefore, the coincidence problem can be naturally solved in the effective YMC dark energy models.

  16. A possible solution to the Dark Matter, Dark Energy, and Pioneer Anomaly problems via a VSL approach

    E-Print Network [OSTI]

    Roee Amit

    2008-02-15

    I apply the equations of motion derived in the accompanying manuscript for the classical approximation of the vsl-path integral to the Newtonian gravitational field in simple geometries. The vsl classical-action, a complex quantity in this case, yields modified Euler-Lagrange equations. This, in turn, leads to the emergence of two equations of motions that must be satisfied concomitantly in order to minimize the complex action. The solutions obtained to the doublet equation of motion include the MOND force law, a dark-energy-like omni-present repulsive gravitational force, a pioneer-like anomaly at the solar system level, and additional predictions, which can be verified with either careful observations or via additional probes to the outer solar system. The exercise carried out in this paper exemplifies the explanatory potential of the vsl-approach, pointing to a potentially new physics paradigm. Finally, the vsl-approach is not only predictive, but highly falsifiable, an important ingredient of any physics theory.

  17. User-needs study for the 1992 Commercial Buildings Energy Consumption Survey. [Energy Consumption Series

    SciTech Connect (OSTI)

    Not Available

    1992-09-01

    The Commercial Buildings Energy Consumption Survey (CBECS) that is conducted by the Energy Information Administration (EIA) is the primary source of energy data for commercial buildings in the United States. The survey began in 1979 and has subsequently been conducted in 1983, 1986, and 1989. The next survey will cover energy consumption during the year 1992. The building characteristic data will be collected between August 1992 and early December 1992. Requests for energy consumption data are mailed to the energy suppliers in January 1993, with data due by March 1993. Before each survey is sent into the field, the data users' needs are thoroughly assessed. The purpose of this report is to document the findings of that user-needs assessment for the 1992 survey.

  18. AQUIFER THERMAL ENERGY STORAGE-A SURVEY

    E-Print Network [OSTI]

    Tsang, Chin Fu

    2012-01-01

    R. C. 1 1972 1 Thermal storage for eco=energy utilities: GE-and Harris, w. B. 0 1978 0 Thermal storage of cold water induration EXPERIMENTS Thermal storage radius (m) thickness

  19. Refraction Survey (Laney, 2005) | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page onRAPID/Geothermal/Exploration/Colorado <RAPID/Geothermal/WaterEnergyRedfield1989) Jump to:| Open EnergyAl.,

  20. NEPA Litigation Surveys | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematicsEnergyInterested Parties -Department of EnergyNEW1 NEPA Determination:

  1. Ultra High Energy Cosmic Ray and UHE Neutrino-Z Showering in Dark Halos

    E-Print Network [OSTI]

    Daniele Fargion; P. G. De Sanctis Lucentini; M. Grossi; M. De Santis; Barbara Mele

    2002-01-03

    The Ultra High Energy Cosmic Ray (UHECR), by UHE neutrino-relic neutrino--Z showering in Hot Dark Halos (HDM), shows an energy spectra, an anisotropy following the relic neutrino masses and clustering in dark halo. The lighter are the relic neutrinos masses, the higher their corresponding Z resonance energy peaks. A twin light neutrino mass splitting may reflect into a twin Z resonance and a complex UHECR spectra modulation as a twin bump at at highest GZK energy cut-off. Each possible neutrino mass associates a characteristic dark halo size (galactic, local, super cluster) and its anisotropy due to our peculiar position within that dark matter distribution. The expected Z or WW,ZZ showering into proton-anti proton and neutron-anti neutron might correspond to peculiar clustering in observed UHECR at 10^{19}, 2 10^{19}, 4 10^{19} eV. A neutrino light HDM halo around a Mpc will allow to the UHECR neutron--anti-neutron secondary component at E_n> 10^{20} eV (due to Z decay) to arise playing a role comparable with the charged p-bar{p} ones. Their un-deflected n-bar{n} flight is shorter leading to a prompt and hard UHECR trace pointing toward the original UHECR source direction. The direct proton-antiproton pairs are split and spread by random magnetic fields into a more diluted and smeared and lower energy UHECR signal around the original source direction. Additional prompt TeVs signals by synchrotron radiation of electro-magnetic Z showering must also occur solving the Infrared-TeV cut-off. The observed hard doublet and triplets spectra, their time and space clustering already favour the rising key role of UHECR n-bar n secondaries originated by neutrino-Z tail shower.

  2. Homeowner and Contractor Surveys | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyTher i nA Guide to TappingWORKof Energy BeforeSavings |Department of

  3. Biofuels Quality Surveys | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyTher i n c i p a l De p uBUSEnergy||slideshow explains the workEnergy

  4. The time evolution of cosmological redshift in non-standard dark energy models

    E-Print Network [OSTI]

    Balbi, A

    2007-01-01

    The variation of the expansion rate of the universe with time produces an evolution in the cosmological redshift of distant sources (for example quasars), that might be directly observed (over a decade or so) by future ultra stable, high-resolution spectrographs (such as CODEX) coupled to extremely large telescopes (such as ESO's ELT). This would open a new window to explore the physical mechanism responsible for the current acceleration of the universe. We investigate the evolution of cosmological redshift from a variety of non-standard dark energy models, and compare it with simulated data based on realistic assumptions. We perform a Fisher matrix analysis, in order to estimate the expected constraints on the parameters of the models. We find that there are interesting prospects for constraining the parameters of non-standard dark energy models and for discriminating among competing candidates.

  5. Tidal energy effects of dark matter halos on early-type galaxies

    E-Print Network [OSTI]

    Valentinuzzi, T; D'Onofrio, M

    2010-01-01

    Tidal interactions between neighboring objects span across the whole admissible range of lengths in nature: from, say, atoms to clusters of galaxies i.e. from micro to macrocosms. According to current cosmological theories, galaxies are embedded within massive non-baryonic dark matter (DM) halos, which affects their formation and evolution. It is therefore highly rewarding to understand the role of tidal interaction between the dark and luminous matter in galaxies. The current investigation is devoted to Early-Type Galaxies (ETGs), looking in particular at the possibility of establishing whether the tidal interaction of the DM halo with the luminous baryonic component may be at the origin of the so-called "tilt" of the Fundamental Plane (FP). The extension of the tensor virial theorem to two-component matter distributions implies the calculation of the self potential energy due to a selected subsystem, and the tidal potential energy induced by the other one. The additional assumption of homeoidally striated d...

  6. Dark Energy from Gauss-Bonnet and non-minimal couplings

    E-Print Network [OSTI]

    L. N. Granda; D. F. Jimenez

    2014-11-16

    We consider a scalar-tensor model of dark energy with Gauss-Bonnet and non-minimal couplings. Exact cosmological solutions were found in absence of potential, that give equations of state of dark energy consistent with current observational constraints, but with different asymptotic behaviors depending on the couplings of the model. A detailed reconstruction procedure is given for the scalar potential and the Gauss-Bonnet coupling for any given cosmological scenario. Particularly, we consider conditions for the existence of a variety of cosmological solutions with accelerated expansion, including quintessence, phantom, de Sitter, Little Rip. For the case of quintessence and phantom we have found a scalar potential of the Albrecht-Skordis type, where the potential is an exponential with a polynomial factor.

  7. A divergence free parametrization of deceleration parameter for scalar field dark energy

    E-Print Network [OSTI]

    Mamon, Abdulla Al

    2015-01-01

    In this paper, we have considered a spatially flat FRW universe filled with pressureless matter and dark energy. We have considered a phenomenological parametrization of the deceleration parameter $q(z)$ and from this we have reconstructed the equation of state for dark energy $\\omega_{\\phi}(z)$. Using the combination of datasets (SN Ia + Hubble + BAO/CMB), we have constrained the transition redshift $z_t$ (at which the universe switches from a decelerating to an accelerating phase) and have found the best fit value of $z_t$. We have also found that the reconstructed results of $q(z)$ and $\\omega_{\\phi}(z)$ are in good agreement with the recent observations. The potential term for the present toy model is found to be functionally similar to a Higgs potential.

  8. Cosmological model-independent Gamma-ray bursts calibration and its cosmological constraint to dark energy

    SciTech Connect (OSTI)

    Xu, Lixin, E-mail: lxxu@dlut.edu.cn [Institute of Theoretical Physics, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 (China)

    2012-04-01

    As so far, the redshift of Gamma-ray bursts (GRBs) can extend to z ? 8 which makes it as a complementary probe of dark energy to supernova Ia (SN Ia). However, the calibration of GRBs is still a big challenge when they are used to constrain cosmological models. Though, the absolute magnitude of GRBs is still unknown, the slopes of GRBs correlations can be used as a useful constraint to dark energy in a completely cosmological model independent way. In this paper, we follow Wang's model-independent distance measurement method and calculate their values by using 109 GRBs events via the so-called Amati relation. Then, we use the obtained model-independent distances to constrain ?CDM model as an example.

  9. Anisotropic model of dark energy dominated universe with hybrid expansion law

    E-Print Network [OSTI]

    Suresh Kumar

    2013-08-22

    The paper deals with the study of the dynamics of Universe within the framework of a spatially homogeneous Bianchi-V space-time filled with a perfect fluid composed of non-interacting matter and dynamical dark energy components. We determine the Bianchi-V space-time by considering hybrid expansion law (HEL) for the average scale factor that yields power-law and exponential-law cosmologies in its special cases. In the HEL cosmology, the Universe exhibits transition from deceleration to acceleration. We find that the HEL Universe within the framework of Bianchi-V space-time is anisotropic at the early stages of evolution and becomes isotropic at late times. The dynamical dark energy in the HEL Bianchi-V Universe does not show departure from the usual cosmological constant at later times.

  10. Input Substitution and Business Energy Consumption: Evidence from ABS Energy Survey Data

    E-Print Network [OSTI]

    1 Input Substitution and Business Energy Consumption: Evidence from ABS Energy Survey Data Kay Cao applies the system of equations approach to energy consumption modelling using the ABS 2008-09 Energy of equations, energy consumption modelling, elasticity of substitution JEL codes: C51, D24 * Please do

  11. Modified Gauss-Bonnet theory as gravitational alternative for dark energy

    E-Print Network [OSTI]

    Shin'ichi Nojiri; Sergei D. Odintsov

    2005-10-06

    We suggest the modified gravity where some arbitrary function of Gauss-Bonnet (GB) term is added to Einstein action as gravitational dark energy. It is shown that such theory may pass solar system tests. It is demonstrated that modified GB gravity may describe the most interesting features of late-time cosmology: the transition from deceleration to acceleration, crossing the phantom divide, current acceleration with effective (cosmological constant, quintessence or phantom) equation of state of the universe.

  12. Exact solutions in a scalar-tensor model of dark energy

    SciTech Connect (OSTI)

    Granda, L.N.; Loaiza, E. E-mail: edwin.loaiza@correounivalle.edu.co

    2012-09-01

    We consider a model of scalar field with non minimal kinetic and Gauss Bonnet couplings as a source of dark energy. Based on asymptotic limits of the generalized Friedmann equation, we impose restrictions on the kinetic an Gauss-Bonnet couplings. This restrictions considerable simplify the equations, allowing for exact solutions unifying early time matter dominance with transitions to late time quintessence and phantom phases. The stability of the solutions in absence of matter has been studied.

  13. Interacting holographic dark energy model and generalized second law of thermodynamics in non-flat universe

    E-Print Network [OSTI]

    M. R. Setare

    2007-01-26

    In the present paper we consider the interacting holographic model of dark energy to investigate the validity of the generalized second laws of thermodynamics in non-flat (closed) universe enclosed by the event horizon measured from the sphere of the horizon named $L$. We show that for $L$ as the system's IR cut-off the generalized second law is respected for the special range of the deceleration parameter.

  14. Non-equilibrium thermodynamics of dark energy on the power-law entropy corrected apparent horizon

    E-Print Network [OSTI]

    M. Umar Farooq; Mubasher Jamil

    2011-11-24

    We investigate the Friedmann-Robertson-Walker (FRW) universe (containing dark energy) as a non-equilibrium (irreversible) thermodynamical system by considering the power-law correction to the horizon entropy. By taking power-law entropy area law which appear in dealing with the entanglement of quantum fields in and out the horizon, we determine the power-law entropy corrected apparent horizon of the FRW universe.

  15. Resembling holographic dark energy with f(R)gravity as scalar field and ghost dark energy with tachyon scalar fields

    E-Print Network [OSTI]

    A. Aghamohammadi

    2014-02-22

    In this article,the dynamics and potential of two different scalar field models is presented in a at Friedmann-Lemaitre-Robertson-Walker(FLRW) universe. One of those models is obtained from the corresponding relation between holographic energy density (HED) with energy density of the corresponding scalar field of f(R) gravity,and other models is achieved from connection between the ghost energy density (GDE) with energy density of the tachyon field model. Also, a f(R) model according to the the HDE model is calculated then stability,anti -gravity and viable conditions on it are investigated.

  16. A survey of state clean energy fund support for biomass

    SciTech Connect (OSTI)

    Fitzgerald, Garrett; Bolinger, Mark; Wiser, Ryan

    2004-08-20

    This survey reviews efforts by CESA member clean energy funds to promote the use of biomass as a renewable energy source. For each fund, details are provided regarding biomass eligibility for support, specific programs offering support to biomass projects, and examples of supported biomass projects (if available). For the purposes of this survey, biomass is defined to include bio-product gasification, combustion, co-firing, biofuel production, and the combustion of landfill gas, though not all of the programs reviewed here take so wide a definition. Programs offered by non-CESA member funds fall outside the scope of this survey. To date, three funds--the California Energy Commission, Wisconsin Focus on Energy, and the New York State Energy Research and Development Authority--have offered programs targeted specifically at the use of biomass as a renewable energy source. We begin by reviewing efforts in these three funds, and then proceed to cover programs in other funds that have provided support to biomass projects when the opportunity has arisen, but otherwise do not differentially target biomass relative to other renewable technologies.

  17. Dynamics of entropy perturbations in assisted dark energy with mixed kinetic terms

    SciTech Connect (OSTI)

    Karwan, Khamphee

    2011-02-01

    We study dynamics of entropy perturbations in the two-field assisted dark energy model. Based on the scenario of assisted dark energy, in which one scalar field is subdominant compared with the other in the early epoch, we show that the entropy perturbations in this two-field system tend to be constant on large scales in the early epoch and hence survive until the present era for a generic evolution of both fields during the radiation and matter eras. This behaviour of the entropy perturbations is preserved even when the fields are coupled via kinetic interaction. Since, for assisted dark energy, the subdominant field in the early epoch becomes dominant at late time, the entropy perturbations can significantly influence the dynamics of density perturbations in the universe. Assuming correlations between the entropy and curvature perturbations, the entropy perturbations can enhance the integrated Sachs-Wolfe (ISW) effect if the signs of the contributions from entropy perturbations and curvature perturbations are opposite after the matter era, otherwise the ISW contribution is suppressed. For canonical scalar field the effect of entropy perturbations on ISW effect is small because the initial value of the entropy perturbations estimated during inflation cannot be sufficiently large. However, in the case of k-essence, the initial value of the entropy perturbations can be large enough to affect the ISW effect to leave a significant imprint on the CMB power spectrum.

  18. Cosmology with space-based gravitational-wave detectors --- dark energy and primordial gravitational waves ---

    E-Print Network [OSTI]

    Atsushi Nishizawa; Kent Yagi; Atsushi Taruya; Takahiro Tanaka

    2012-02-24

    Proposed space-based gravitational-wave (GW) detectors such as DECIGO and BBO will detect ~10^6 neutron-star (NS) binaries and determine the luminosity distances to the binaries with high precision. Combining the luminosity distances with cosmologically-induced phase corrections on the GWs, cosmological expansion out to high redshift can be measured without the redshift determinations of host galaxies by electromagnetic observation and be a unique probe for dark energy. On the other hand, such a NS-binary foreground should be subtracted to detect primordial GWs produced during inflation. Thus, the constraining power on dark energy and the detectability of the primordial gravitational waves strongly depend on the detector sensitivity and are in close relation with one another. In this paper, we investigate the constraints on the equation of state of dark energy with future space-based GW detectors with/without identifying the redshifts of host galaxies. We also study the sensitivity to the primordial GWs, properly dealing with the residual of the NS binary foreground. Based on the results, we discuss the detector sensitivity required to achieve the forementioned targeted study of cosmology.

  19. Holographic dark energy models with statefinder diagnostic in modified $f(R,T)$ gravity

    E-Print Network [OSTI]

    C. P. Singh; Pankaj Kumar

    2015-10-14

    We study non-viscous and viscous holographic dark energy models for a homogeneous and isotropic flat Friedmann-Robertson-Walker Universe in $f(R,T)$ gravity. We find that the Hubble horizon as an IR cut-off is suitable for both the models to explain the recent accelerated expansion of the Universe. The cosmological parameters like deceleration parameter and statefinder parameters are discussed in each model. In non-viscous model a constant deceleration parameter is found which shows that there is no phase transition. The constraints on the parameters are obtained to analyse the fixed point values of statefinder parameters of SCDM and $\\Lambda$CDM models. We know that the phase transition is required to explain the accelerated expansion of the Universe and this is possible if both the parameters would be time-dependent. Therefore, we extend our analysis to viscous holographic dark energy model to investigate whether this viscous model with the same IR cut-off could be helpful to find the phase transition. We find that this model gives a time-dependent deceleration parameter which achieves a smooth phase transition of the Universe. We also find the time-varying statefinder pair which matches with $\\Lambda$CDM model. We plot the trajectories in $r-s$ and $r-q$ plans to discriminate our model with the existing dark energy models and obtain the quintessence like behaviour for the suitable values of parameters.

  20. Reflection Survey (Ozkocak, 1985) | Open Energy Information

    Open Energy Info (EERE)

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