National Library of Energy BETA

Sample records for dark energy mission

  1. Searching for Dark Energy

    SciTech Connect (OSTI)

    Schlegel, David

    2015-05-06

    Berkeley Lab scientist David Schlegel discusses his research on mapping the universe and understanding dark energy.

  2. Mission | Department of Energy

    Office of Environmental Management (EM)

    Mission Mission OSDBU is building sustainable small businesses to enable the Department of Energy to achieve its mission, through innovation and creativity. Sections 8 and 15 of ...

  3. Jelly Bean Universe (Dark Matter / Dark Energy)

    ScienceCinema (OSTI)

    Kurt Riesselmann

    2010-01-08

    Fermilab's Kurt Riesselmann explains how to make a jelly bean universe to help explain the mysteries of dark matter and dark energy.

  4. Jelly Bean Universe (Dark Matter / Dark Energy)

    SciTech Connect (OSTI)

    Kurt Riesselmann

    2009-09-10

    Fermilab's Kurt Riesselmann explains how to make a jelly bean universe to help explain the mysteries of dark matter and dark energy.

  5. Mission | Department of Energy

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

    About Energy.gov » Mission Mission The mission of the Energy Department is to ensure America's security and prosperity by addressing its energy, environmental and nuclear challenges through transformative science and technology solutions. Energy Catalyze the timely, material, and efficient transformation of the nation's energy system and secure U.S. leadership in clean energy technologies. Learn more Topics Energy Economy Energy Efficiency Energy Sources Energy Usage Science & Innovation

  6. Mission | Department of Energy

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

    Mission Mission The mission of the U.S. Department of Energy (DOE) Office of Indian Energy Policy and Programs is to maximize the development and deployment of energy solutions for the benefit of American Indians and Alaska Natives. The Office works within DOE, across government agencies, and with Indian tribes and organizations to promote Indian energy policies and initiatives. The Office of Indian Energy performs these functions within the scope of DOE's mission and consistently with the

  7. 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.

  8. Dark Energy, or Worse

    SciTech Connect (OSTI)

    Carroll, Sean

    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.

  9. Mission | Department of Energy

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

    Mission Mission The mission of the Office of the Chief Information Officer (OCIO) is to enable the Department of Energy's urgent missions in energy, science and nuclear security through the power of information and technology in a manner that balances risk with required outcomes in programs that span from open science to national security. OCIO Strategic Plan Vision, Leadership and Commitment...Enabling the Future through Technology and Information

  10. 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.

  11. 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.

  12. Mission | Department of Energy

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

    Mission Mission Our mission is to remove environmental legacies resulting from more than 60 years nuclear weapons development and government-sponsored nuclear energy research. Each of Oak Ridge's three primary cleanup sites face unique challenges that threaten safety and hinder the Department's missions. Protecting the Region's Health and Environment Our employees understand that their progress enhances the health and safety of the region. At ETTP, we are removing contaminated facilities. At

  13. NEET Mission | Department of Energy

    Energy Savers [EERE]

    NEET Mission NEET Mission The mission of the Nuclear Energy Enabling Technologies (NEET) program is to develop crosscutting technologies that directly support and complement the ...

  14. 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.

  15. The Dark Energy

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

    Dark Energy Survey: the Movie Brenna Flaugher Josh Frieman Marcelle Soares-Santos John Peoples December 16, 2015 4:00 p.m. - Ramsey Auditorium This public colloquium will center on a showing of a documentary film made by independent Spanish film maker Alex Muntada about cosmic surveys and the laws of physics, with primary focus on the Dark Energy Survey. The Nobel Prize for Physics in 2011 was awarded for the discovery in the late 1990s that the expansion of the Universe is speeding up. Yet the

  16. 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.

  17. Mission | Department of Energy

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

    Mission Mission The Mission of the Office of Management is to provide the Department of Energy with centralized direction and oversight for the full range of management, procurement and administrative services. Project Management Project Management Awardees The Office of Management's activities include project and contract management, cost estimating, and policy development and oversight, One of the principal outcomes in exercising this responsibility is the delivery of projects on schedule,

  18. Dark Energy | Argonne National Laboratory

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

    Dark Energy Dark Energy The Dark Energy Survey (DES) is a joint project between the U.S. Department of Energy and the National Science Foundation to study the nature of dark matter and dark energy. Dark matter and energy are believed to make up 95 percent of the universe, and their origin and composition are completely unknown. The DES has built a new 520 mega-pixel CCD camera for an existing 4-meter telescope in Chile that will be used for a five-year program of observations. These new

  19. In the OSTI Collections: Dark Matter and Dark Energy | OSTI,...

    Office of Scientific and Technical Information (OSTI)

    Dark Matter and Dark Energy Recent observations of the universe, combined with Einstein's ... consists of entities very different from the matter and energy long familiar to us. ...

  20. NASA and DOE Collaborate on Dark Energy Research | Department of Energy

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

    NASA and DOE Collaborate on Dark Energy Research NASA and DOE Collaborate on Dark Energy Research November 19, 2008 - 4:58pm Addthis WASHINGTON, DC -- NASA and the U.S. Department of Energy (DOE) have signed a memorandum of understanding for the implementation of the Joint Dark Energy Mission, or JDEM. The mission will feature the first space-based observatory designed specifically to understand the nature of dark energy. Dark energy is a form of energy that pervades and dominates the universe.

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

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

    Dark matter and dark energy photo Visible matter makes up just 4 percent of the contents of the universe; the remaining 96 percent is made of dark matter and dark energy. Scientists discovered both by observing their cosmic effects but have yet to directly detect either. Fermilab experiments seek to uncover the mysteries of the dark universe. Scientists discovered dark matter by studying the behavior of neighboring galaxies and galaxy clusters. They could not explain the way the galaxies moved

  2. The Dark Energy Camera

    SciTech Connect (OSTI)

    Flaugher, B.

    2015-04-11

    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-μm thick fully depleted CCDs cooled inside a vacuum Dewar. The 570 Mpixel focal plane comprises 62 2k x 4k CCDs for imaging and 12 2k x 2k CCDs for guiding and focus. The CCDs have 15μm x 15μm pixels with a plate scale of 0.263" 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, construction, installation, and current status.

  3. Mission | Department of Energy

    Office of Environmental Management (EM)

    structured to accomplish departmental missions Implements departmental policy ... legacy waste and changing departmental missions Actively acts as liaison and coordinates ...

  4. Optimizing New Dark Energy Experiments

    SciTech Connect (OSTI)

    Tyson, J. Anthony

    2013-08-26

    Next generation “Stage IV” dark energy experiments under design during this grant, and now under construction, will enable the determination of the properties of dark energy and dark matter to unprecedented precision using multiple complementary probes. The most pressing challenge in these experiments is the characterization and understanding of the systematic errors present within any given experimental configuration and the resulting impact on the accuracy of our constraints on dark energy physics. The DETF and the P5 panel in their reports recommended “Expanded support for ancillary measurements required for the long-term program and for projects that will improve our understanding and reduction of the dominant systematic measurement errors.” Looking forward to the next generation Stage IV experiments we have developed a program to address the most important potential systematic errors within these experiments. Using data from current facilities it has been feasible and timely to undertake a detailed investigation of the systematic errors. In this DOE grant we studied of the source and impact of the dominant systematic effects in dark energy measurements, and developed new analysis tools and techniques to minimize their impact. Progress under this grant is briefly reviewed in this technical report. This work was a necessary precursor to the coming generations of wide-deep probes of the nature of dark energy and dark matter. The research has already had an impact on improving the efficiencies of all Stage III and IV dark energy experiments.

  5. Mission | Department of Energy

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

    Mission Mission To strengthen the integrity, economy, and efficiency of the Department's programs and operations. Vision Statement To be a highly effective organization that promotes positive change.

  6. Mission | Department of Energy

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

    HUMAN CAPITAL MISSION AND VISION Mission: The Office of the Chief Human Capital Officer (OCHCO) provides effective leadership on policies, programs, and partnerships related to all ...

  7. EERE Mission | Department of Energy

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

    EERE Mission EERE Mission The mission of the Office of Energy Efficiency and Renewable Energy (EERE) is to create and sustain American leadership in the transition to a global clean energy economy. Its vision is a strong and prosperous America powered by clean, affordable and secure energy. Renewable Electricity Generation Image of two workers installing solar panels. EERE plays a key role in advancing America's "all of the above" energy strategy, leading a large network of researchers

  8. Berkeley Algorithms Help Researchers Understand Dark Energy

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

    Algorithms Help Researchers Understand Dark Energy Berkeley Algorithms Help Researchers Understand Dark Energy November 24, 2014 Contact: Linda Vu, +1 510 495 2402, lvu@lbl.gov ...

  9. Dark energy and dark matter from primordial QGP

    SciTech Connect (OSTI)

    Vaidya, Vaishali Upadhyaya, G. K.

    2015-07-31

    Coloured relics servived after hadronization might have given birth to dark matter and dark energy. Theoretical ideas to solve mystery of cosmic acceleration, its origin and its status with reference to recent past are of much interest and are being proposed by many workers. In the present paper, we present a critical review of work done to understand the earliest appearance of dark matter and dark energy in the scenario of primordial quark gluon plasma (QGP) phase after Big Bang.

  10. Mission | Department of Energy

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

    Mission Mission The Office of Economic Impact and Diversity develops and executes Department-wide policies to implement applicable legislation and Executive Orders that strengthen diversity and inclusion goals affecting equal employment opportunities, small and disadvantaged businesses, minority educational institutions, and historically under-represented communities. Our mission is to identify and implement ways of ensuring that everyone is afforded an opportunity to participate fully in the

  11. 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.

  12. Voids and overdensities of coupled Dark Energy

    SciTech Connect (OSTI)

    Mainini, Roberto

    2009-04-15

    We investigate the clustering properties of dynamical Dark Energy even in association of a possible coupling between Dark Energy and Dark Matter. We find that within matter inhomogeneities, Dark Energy migth form voids as well as overdensity depending on how its background energy density evolves. Consequently and contrarily to what expected, Dark Energy fluctuations are found to be slightly suppressed if a coupling with Dark Matter is permitted. When considering density contrasts and scales typical of superclusters, voids and supervoids, perturbations amplitudes range from |{delta}{sub {phi}}| {approx} O(10{sup -6}) to |{delta}{sub {phi}}| {approx} O(10{sup -4}) indicating an almost homogeneous Dark Energy component.

  13. Mission | Department of Energy

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

    Mission Mission National Environmental Policy Act of 1969 (NEPA) NEPA is our basic national charter for protection of the environment. Signed into law by President Richard Nixon on January 1, 1970, NEPA was established to foster and promote the general welfare, to create and maintain conditions under which man and nature can exist in productive harmony, and fulfill the social, economic, and other requirements of present and future generations of Americans. NEPA establishes policy, sets goals

  14. DOE Science Showcase - Dark Matter and Dark Energy | OSTI, US...

    Office of Scientific and Technical Information (OSTI)

    cosmos to you, Science.gov Saul Perlmutter, LBNL physicists and 2011 Nobel laureate, discusses Dark Energy and the Accelerating Universe, DOE Office of Science DOE Office of ...

  15. 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.

  16. Energy Saver Mission | Department of Energy

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

    About Us » Energy Saver Mission Energy Saver Mission Energy Saver provides energy efficiency and renewable energy information to consumers in the United States, including families, homeowners, renters, and drivers. Explore the following information and resources from Energy Saver: Heating and Cooling Photo of a thermostat phone app being held in front of a wall-mounted thermostat. Energy Saver offers information on your options for home heating and cooling and water heating, as well as tips for

  17. Sandia Energy Mission

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

    Sandia's Energy & Climate PMU to Participate in July 8th National Lab Day on Capitol Hill http:energy.sandia.govsandias-energy-climate-pmu-to-participate-in-july-8th-national-la...

  18. Mission | Department of Energy

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

    ECONOMIC GROWTH, JOB CREATION & MORE CLEAN ENERGY SOURCES Specifically, LPO endeavors to: ... LPO FINANCES THE GROWTH OF THESE INNOVATIVE CLEAN ENERGY TECHNOLOGIES: Biomass Hydrogen ...

  19. Mission | Department of Energy

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

    is the primary energy policy advisor to the Secretary and Deputy Secretary on domestic energy policy development and implementation as well as DOE policy analysis and activities. ...

  20. Mission | Department of Energy

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

    national, economic, and energy security of the United States through scientific and technological innovation and the environmental cleanup of the national nuclear weapons complex.

  1. Mission | Department of Energy

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

    Advise the Secretary, Deputy Secretary, and other relevant DOE leadership on strategic implementation of the United States' international energy policy. Lead and develop the ...

  2. Mission | Department of Energy

    Energy Savers [EERE]

    Executing Natural Gas Regulatory Responsibilities The Office of Fossil Energy regulates natural gas and LNG imports and exports under Section 3 of the Natural Gas Act of 1938. ...

  3. Mission | Department of Energy

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

    the Secretary may delegate, and to support the use of alternative means to resolve disputes in DOE's activities. Careers & Internships Information Center Contact Us Energy.gov

  4. Mission | Department of Energy

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

    and evaluation, finance and accounting, internal controls, corporate financial systems, and strategic planning. Careers & Internships Congressional Reports Contact Us Energy.gov

  5. Mission | Department of Energy

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

    with Members of Congress, other levels of governments and stakeholders which includes consumer liaison, and public interest groups. Careers & Internships Contact Us Energy.gov

  6. 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...

  7. The Dark Energy Survey: More than dark energy - An overview

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

    Abbott, T.

    2016-03-21

    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 andmore » 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, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from `Science Verification', and from the first, second and third seasons of observations), what DES can tell us about the solar system, the Milky Way, galaxy evolution, quasars, and other topics. In addition, we show that if the cosmological model is assumed to be Lambda+ Cold Dark Matter (LCDM) then important astrophysics can be deduced from the primary DES probes. Lastly, highlights from DES early data include the discovery of 34 Trans Neptunian Objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed).« less

  8. Berkeley Algorithms Help Researchers Understand Dark Energy

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

    Algorithms Help Researchers Understand Dark Energy Berkeley Algorithms Help Researchers Understand Dark Energy November 24, 2014 Contact: Linda Vu, +1 510 495 2402, lvu@lbl.gov Scientists believe that dark energy-the mysterious force that is accelerating cosmic expansion-makes up about 70 percent of the mass and energy of the universe. But because they don't know what it is, they cannot observe it directly. To unlock the mystery of dark energy and its influence on the universe, researchers

  9. 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.

  10. DOE Science Showcase - Dark Matter and Dark Energy | OSTI, US Dept of

    Office of Scientific and Technical Information (OSTI)

    Energy Office of Scientific and Technical Information Dark Matter and Dark Energy The nature of dark energy or invisible energy is one of the universe's most compelling mysteries and its resolution is likely to completely change our understanding of matter, space, and time. For more information, see In the OSTI Collections: Dark Matter and Dark Energy, by Dr. William Watson, Physicist, OSTI staff. Gravitational lensing, or the warping of light around massive objects is one sign of dark

  11. 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.

  12. Neutrino mass, dark energy, and the linear growth factor (Journal...

    Office of Scientific and Technical Information (OSTI)

    dark energy, and the linear growth factor Citation Details In-Document Search Title: Neutrino mass, dark energy, and the linear growth factor We study the degeneracies between ...

  13. Saul Perlmutter, Distant Supernovae, Dark Energy, and the Accelerating...

    Office of Scientific and Technical Information (OSTI)

    Saul Perlmutter, Distant Supernovae, Dark Energy, and the Accelerating Expansion of the ... studies to determine the nature of dark energy.'1 'The accelerating expansion means that ...

  14. #LabChat Recap: What is Dark Energy

    Office of Energy Efficiency and Renewable Energy (EERE)

    The Dark Energy #LabChat on Oct. 25 yielded a lively discussion with three physicists about inflation, super symmetry, black holes and, of course, dark energy.

  15. 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...

  16. NPS Mission | Open Energy Information

    Open Energy Info (EERE)

    Mission Jump to: navigation, search OpenEI Reference LibraryAdd to library Web Site: NPS Mission Author National Park Service Published National Park Service, Date Not Provided DOI...

  17. Evidence for Dark Energy | GE Global Research

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

    Has Evidence of Dark Energy Been Discovered? Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new window) ...

  18. Dark matter and dark energy: The critical questions (Conference...

    Office of Scientific and Technical Information (OSTI)

    The critical questions are: (1) What form do the dark baryons take? (2) What is (are) the constituent(s) of the cold dark matter? (3) What is the nature of the mysterious dark ...

  19. Mission Motors | Open Energy Information

    Open Energy Info (EERE)

    External resources Los Angeles Times Auto Blog Autobloggreen Treehugger.com Autopia (Wired) References "Mission Motors: Contact" Retrieved from "http:en.openei.orgw...

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

    Office of Scientific and Technical Information (OSTI)

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

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

    Office of Scientific and Technical Information (OSTI)

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

  2. 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.

  3. Mission

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

    Mission Proud Legacy, Bold Future, Since 1943 Mission Los Alamos National Laboratory's mission is to solve national security challenges through scientific excellence. Mission, Vision, Values» Goals, Strategies» Nuclear Deterrence and Stockpile Stewardship» Protecting Against Nuclear Threats» Emerging Threats and Opportunities» Energy Security Solutions» Cibola satellite Scientist, Daniel Seitz, works on the Cibola satellite at LANL. Cibola is part of the U.S. Department of Defense Space

  4. Dark Energy Cam: Fermilab Expands Understanding of Expanding Universe |

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

    Department of Energy Dark Energy Cam: Fermilab Expands Understanding of Expanding Universe Dark Energy Cam: Fermilab Expands Understanding of Expanding Universe March 12, 2012 - 12:06pm Addthis Researchers at Fermi National Lab team stand beside the 570-megapixels, five-ton Dark Energy camera, which will be capable of measuring the expansion of the universe - and developing better models about how dark energy works. | Photo by Reidar Hahn, Fermi National Lab Researchers at Fermi National Lab

  5. Sub-horizon evolution of cold dark matter perturbations through dark matter-dark energy equivalence epoch

    SciTech Connect (OSTI)

    Piattella, O.F.; Martins, D.L.A.; Casarini, L. E-mail: denilsonluizm@gmail.com

    2014-10-01

    We consider a cosmological model of the late universe constituted by standard cold dark matter plus a dark energy component with constant equation of state w and constant effective speed of sound. By neglecting fluctuations in the dark energy component, we obtain an equation describing the evolution of sub-horizon cold dark matter perturbations through the epoch of dark matter-dark energy equality. We explore its analytic solutions and calculate an exact w-dependent correction for the dark matter growth function, logarithmic growth function and growth index parameter through the epoch considered. We test our analytic approximation with the numerical solution and find that the discrepancy is less than 1% for 0k = during the cosmic evolution up to a = 100.

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

    Office of Environmental Management (EM)

    lies about 17,000 light years from Earth. | Photo by Dark Energy Survey Collaboration. ... Among the camera's jaw-dropping statistics, it has a weight of 4 to 5 tons and contains ...

  7. Mission

    Broader source: Energy.gov [DOE]

    The primary mission of the Office of Nuclear Energy is to advance nuclear power as a resource capable of meeting the Nation's energy, environmental, and national security needs by resolving...

  8. Simple implementation of general dark energy models

    SciTech Connect (OSTI)

    Bloomfield, Jolyon K.; Pearson, Jonathan A. E-mail: jonathan.pearson@durham.ac.uk

    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.

  9. Mission, Kansas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Map This article is a stub. You can help OpenEI by expanding it. Mission is a city in Johnson County, Kansas. It falls under Kansas's 3rd congressional district.12 Registered...

  10. DOC-DOE Joint China Mission Statement | Department of Energy

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

    Joint China Mission Statement DOC-DOE Joint China Mission Statement DOC-DOE Joint China Mission Statement DOC-DOE Joint China Mission Statement (109.75 KB) More Documents & Publications DOC-DOE China Mission Announcement Press Release FACT SHEET: U.S.-China Clean Energy Cooperation Announcements US-China Clean Energy Cooperation

  11. DARK FLUID: A UNIFIED FRAMEWORK FOR MODIFIED NEWTONIAN DYNAMICS, DARK MATTER, AND DARK ENERGY

    SciTech Connect (OSTI)

    Zhao Hongsheng; Li Baojiu E-mail: b.li@damtp.cam.ac.u

    2010-03-20

    Empirical theories of dark matter (DM) like modified Newtonian dynamics (MOND) gravity and of dark energy (DE) like f(R) gravity were motivated by astronomical data. But could these theories be branches rooted from a more general and hence generic framework? Here we propose a very generic Lagrangian of such a framework based on simple dimensional analysis and covariant symmetry requirements, and explore various outcomes in a top-down fashion. The desired effects of quintessence plus cold DM particle fields or MOND-like scalar field(s) are shown to be largely achievable by one vector field only. Our framework preserves the covariant formulation of general relativity, but allows the expanding physical metric to be bent by a single new species of dark fluid flowing in spacetime. Its non-uniform stress tensor and current vector are simple functions of a vector field with variable norm, not coupled with the baryonic fluid and the four-vector potential of the photon fluid. The dark fluid framework generically branches into a continuous spectrum of theories with DE and DM effects, including the f(R) gravity, tensor-vector-scalar-like theories, Einstein-Aether, and nuLAMBDA theories as limiting cases. When the vector field degenerates into a pure scalar field, we obtain the physics for quintessence. Choices of parameters can be made to pass Big Bang nucleosynthesis, parameterized post-Newtonian, and causality constraints. In this broad setting we emphasize the non-constant dynamical field behind the cosmological constant effect, and highlight plausible corrections beyond the classical MOND predictions.

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

    Office of Scientific and Technical Information (OSTI)

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

  13. 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.

  14. OSTI Mission | OSTI, US Dept of Energy, Office of Scientific...

    Office of Scientific and Technical Information (OSTI)

    OSTI Mission OSTI Mission: To advance science and sustain technological creativity by making R&D findings available and useful to Department of Energy (DOE) researchers and the ...

  15. 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 α of Ricci dark energy equals to 1/2. In the case where α = 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.

  16. Structure formation in inhomogeneous Early Dark Energy models

    SciTech Connect (OSTI)

    Batista, R.C.; Pace, F. E-mail: francesco.pace@port.ac.uk

    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 ΛCDM 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 δ{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 ΛCDM 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 ΛCDM model than its homogeneous counterparts.

  17. 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.

  18. Aetherizing Lambda: Barotropic fluids as dark energy

    SciTech Connect (OSTI)

    Linder, Eric V.; Scherrer, Robert J.

    2009-07-15

    We examine the class of barotropic fluid models of dark energy, in which the pressure is an explicit function of the density, p=f({rho}). Through general physical considerations we constrain the asymptotic past and future behaviors and show that this class is equivalent to the sum of a cosmological constant and a decelerating perfect fluid, or 'aether', with w{sub AE}{>=}0. Barotropic models give substantially disjoint predictions from quintessence, except in the limit of {lambda}CDM. They are also interesting in that they simultaneously can ameliorate the coincidence problem and yet 'predict' a value of w{approx_equal}-1.

  19. 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)

  20. Final Technical Report: Discovering the Nature of Dark Energy: Towards

    Office of Scientific and Technical Information (OSTI)

    Better Distances from Type Ia Supernovae (Technical Report) | SciTech Connect Final Technical 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 Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae The final technical report from the project "Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae" led at

  1. In the OSTI Collections: Dark Matter and Dark Energy | OSTI, US Dept of

    Office of Scientific and Technical Information (OSTI)

    Energy Office of Scientific and Technical Information Dark Matter and Dark Energy Recent observations of the universe, combined with Einstein's theory of general relativity, indicate that most of the universe consists of entities very different from the matter and energy long familiar to us. These previously unknown entities are beginning to be explored on several fronts, many through Department of Energy sponsorship. Albert Einstein's theory of relativity describes space and time as

  2. 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.

  3. Stable gravastars of anisotropic dark energy

    SciTech Connect (OSTI)

    Chan, R.; Silva, M.F.A. da; Rocha, P.; Wang, Anzhong E-mail: mfasnic@gmail.com E-mail: anzhong_wang@baylor.edu

    2009-03-15

    Dynamical models of prototype gravastars made of anisotropic dark energy fluid are constructed, in which an infinitely thin spherical shell of a perfect fluid with the equation of state p = (1-{gamma}){sigma} divides the whole spacetime into two regions, the internal region is filled with an anisotropic dark energy fluid, and the external region is the Schwarzschild. 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 normal stars. In the phase space, the region for the ''bounded excursion'' gravastars is very small in comparison to that of black holes, but not empty, as found in our previous papers. Therefore, although the existence of gravastars can not be completely excluded from current analysis, the opposite is not possible either, that is, even if gravastars exist, they do not exclude the existence of black holes.

  4. The Dark Energy Survey Camera (DECam)

    SciTech Connect (OSTI)

    Diehl, H.Thomas; /Fermilab

    2011-09-09

    The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding the expansion rate of the Universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the survey, the DES Collaboration is building the Dark Energy Camera (DECam), a 3 square degree, 570 Megapixel CCD camera that will be mounted at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory. CCD production has finished, yielding roughly twice the required 62 2k x 4k detectors. The construction of DECam is nearly finished. Integration and commissioning on a 'telescope simulator' of the major hardware and software components, except for the optics, recently concluded at Fermilab. Final assembly of the optical corrector has started at University College, London. Some components have already been received at CTIO. 'First-light' will be sometime in 2012. This oral presentation concentrates on the technical challenges involved in building DECam (and how we overcame them), and the present status of the instrument.

  5. Photometric Redshifts for the Dark Energy Survey and VISTA and...

    Office of Scientific and Technical Information (OSTI)

    We conduct a detailed analysis of the photometric redshift requirements for the proposed Dark Energy Survey (DES) using two sets of mock galaxy simulations and an artificial neural ...

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

    Office of Scientific and Technical Information (OSTI)

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

  7. Observational Constraints on the Nature of the Dark Energy: First...

    Office of Scientific and Technical Information (OSTI)

    Observational Constraints on the Nature of the Dark Energy: First Cosmological Results From the ESSENCE Supernova Survey Citation Details In-Document Search Title: Observational...

  8. 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...

  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. COLLOQUIUM: Probing the Accelerating Universe with the Dark Energy...

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

    MBG Auditorium, PPPL (284 cap.) COLLOQUIUM: Probing the Accelerating Universe with the Dark Energy Survey Dr. Joshua Frieman Fermilab and the University of Chicago Presentation: ...

  11. Mission

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

    Mission The Nevada National Security Site (NNSS) CTOS program mission is to develop and deliver the most realistic and highest quality training in support of homeland security using extensive radiological expertise with the unique assets of the NNSS. Background The U.S. Department of Energy, National Nuclear Security Administration (NNSA) is a member of the National Domestic Preparedness Consortium. CTOS develops and conducts training courses for U.S. Department of Homeland Security (DHS)

  12. Chameleon dark energy models with characteristic signatures

    SciTech Connect (OSTI)

    Gannouji, Radouane; Moraes, Bruno; Polarski, David; Mota, David F.; Winther, Hans A.; Tsujikawa, Shinji

    2010-12-15

    In chameleon dark energy models, local gravity constraints tend to rule out parameters in which observable cosmological signatures can be found. We study viable chameleon potentials consistent with a number of recent observational and experimental bounds. A novel chameleon field potential, motivated by f(R) gravity, is constructed where observable cosmological signatures are present both at the background evolution and in the growth rate of the perturbations. We study the evolution of matter density perturbations on low redshifts for this potential and show that the growth index today {gamma}{sub 0} can have significant dispersion on scales relevant for large scale structures. The values of {gamma}{sub 0} can be even smaller than 0.2 with large variations of {gamma} on very low redshifts for the model parameters constrained by local gravity tests. This gives a possibility to clearly distinguish these chameleon models from the {Lambda}-cold-dark-matter ({Lambda}CDM) model in future high-precision observations.

  13. Calibration Monitor for Dark Energy Experiments

    SciTech Connect (OSTI)

    Kaiser, M. E.

    2009-11-23

    The goal of this program was to design, build, test, and characterize a flight qualified calibration source and monitor for a Dark Energy related experiment: ACCESS - 'Absolute Color Calibration Experiment for Standard Stars'. This calibration source, the On-board Calibration Monitor (OCM), is a key component of our ACCESS spectrophotometric calibration program. The OCM will be flown as part of the ACCESS sub-orbital rocket payload in addition to monitoring instrument sensitivity on the ground. The objective of the OCM is to minimize systematic errors associated with any potential changes in the ACCESS instrument sensitivity. Importantly, the OCM will be used to monitor instrument sensitivity immediately after astronomical observations while the instrument payload is parachuting to the ground. Through monitoring, we can detect, track, characterize, and thus correct for any changes in instrument senstivity over the proposed 5-year duration of the assembled and calibrated instrument.

  14. Nuclear Systems Powering a Mission to Mars | Department of Energy

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

    Systems Powering a Mission to Mars Nuclear Systems Powering a Mission to Mars November 28, 2011 - 11:23am Addthis Radioisotope Power Systems, a strong partnership between the Energy Department's Office of Nuclear Energy and NASA, has been providing the energy for deep space exploration. Assistant Secretary Lyons Assistant Secretary Lyons Assistant Secretary for Nuclear Energy Curiosity Mission: investigate whether the Gale Crater on Mars has ever offered environmental conditions that support the

  15. 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.

  16. 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; DellAntonio, 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-zs): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-zs 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

  17. 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

  18. #LabChat: What is Dark Energy? Oct 25 at 2pm ET | Department of Energy

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

    What is Dark Energy? Oct 25 at 2pm ET #LabChat: What is Dark Energy? Oct 25 at 2pm ET October 23, 2012 - 3:03pm Q&A #LabChat Oct 25, 2 pm ET | These physicists are using advanced telescopes and cameras to look for proof of dark energy. Ask them your questions. Ask Us Addthis What is dark energy? Learn about the force we think accounts for three-quarters of the mass and energy in the known universe. What is dark energy? Learn about the force we think accounts for three-quarters of the mass

  19. Trane - Advancing Today's Federal Government Mission | Department of Energy

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

    Trane - Advancing Today's Federal Government Mission Trane - Advancing Today's Federal Government Mission Document describes the qualification sheet for Trane - Advancing Today's Federal Government Mission. Download the Trane qualification sheet. (264.09 KB) More Documents & Publications Tribal Energy Project Development Through ESCOs Frequently Asked Questions about ESPCs Presentations from the Regional Small Business Summits

  20. Cosmological viability conditions for f(T) dark energy models

    SciTech Connect (OSTI)

    Setare, M.R.; Mohammadipour, N. E-mail: N.Mohammadipour@uok.ac.ir

    2012-11-01

    Recently f(T) modified teleparallel gravity where T is the torsion scalar has been proposed as the natural gravitational alternative for dark energy. We perform a detailed dynamical analysis of these models and find conditions for the cosmological viability of f(T) dark energy models as geometrical constraints on the derivatives of these models. We show that in the phase space exists two cosmologically viable trajectory which (i) The universe would start from an unstable radiation point, then pass a saddle standard matter point which is followed by accelerated expansion de sitter point. (ii) The universe starts from a saddle radiation epoch, then falls onto the stable matter era and the system can not evolve to the dark energy dominated epoch. Finally, for a number of f(T) dark energy models were proposed in the more literature, the viability conditions are investigated.

  1. Dark Energy: A Universe Out of Control Nicholas B. Suntzeff....

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

    Dark Energy: A Universe Out of Control Nicholas B. Suntzeff. Ph. D. MitchellHeepMunnerlyn Professor of Observational Astronomy Texas A&M University Nobel Prize in Physics 2011 ...

  2. 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.

  3. Interacting agegraphic quintessence dark energy in non-flat universe

    SciTech Connect (OSTI)

    Sheykhi, A.; Bagheri, A.; Yazdanpanah, M.M. E-mail: ali.bagheri25@yahoo.com

    2010-09-01

    We establish a correspondence between interacting agegraphic dark energy model and the quintessence scalar field in a non-flat universe. We demonstrate that the agegraphic evolution of the universe can be described completely by a single quintessence scalar field. We also reconstruct the potential of the interacting agegraphic quintessence dark energy as well as the dynamics of the quintessence scalar field which describe the quintessence cosmology.

  4. 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.

  5. Department of Energy Strategic Plan Mission Card, May 2011

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

    Mission: To ensure America's security and prosperity by addressing its energy, environmental, and nuclear challenges ... Goal 4: Management and Operational Excellence Establish ...

  6. Mission Biofuels India Pvt Ltd MBIPL | Open Energy Information

    Open Energy Info (EERE)

    Biofuels India Pvt Ltd MBIPL Jump to: navigation, search Name: Mission Biofuels India Pvt Ltd (MBIPL) Place: Mumbai, Maharashtra, India Zip: 400076 Sector: Wind energy Product:...

  7. Joint Trade Mission to China | Department of Energy

    Energy Savers [EERE]

    mission to China focused on smart cities and green infrastructure. Secretary of Commerce Penny Pritzker and Deputy Secretary of Energy Elizabeth Sherwood-Randall are leading 25 ...

  8. Energy-Focused Trade Mission Will Yield Positive Effects for...

    Office of Environmental Management (EM)

    landed in China to lead a presidential trade mission focused on connecting U.S. businesses with opportunities in the green infrastructure and energy efficiency industries. ...

  9. Reconstruction of dark energy and expansion dynamics using Gaussian processes

    SciTech Connect (OSTI)

    Seikel, Marina; Clarkson, Chris; Smith, Mathew E-mail: chris.clarkson@uct.ac.za

    2012-06-01

    An important issue in cosmology is reconstructing the effective dark energy equation of state directly from observations. With few physically motivated models, future dark energy studies cannot only be based on constraining a dark energy parameter space, as the errors found depend strongly on the parametrisation considered. We present a new non-parametric approach to reconstructing the history of the expansion rate and dark energy using Gaussian Processes, which is a fully Bayesian approach for smoothing data. We present a pedagogical introduction to Gaussian Processes, and discuss how it can be used to robustly differentiate data in a suitable way. Using this method we show that the Dark Energy Survey - Supernova Survey (DES) can accurately recover a slowly evolving equation of state to σ{sub w} = ±0.05 (95% CL) at z = 0 and ±0.25 at z = 0.7, with a minimum error of ±0.025 at the sweet-spot at z ∼ 0.16, provided the other parameters of the model are known. Errors on the expansion history are an order of magnitude smaller, yet make no assumptions about dark energy whatsoever. A code for calculating functions and their first three derivatives using Gaussian processes has been developed and is available for download.

  10. Mission Motors Company | Open Energy Information

    Open Energy Info (EERE)

    Place: San Francisco, California Zip: 94103 Product: San Francisco-based electric Motorcycle manufacturer. References: Mission Motors Company1 This article is a stub. You can...

  11. Space Nuclear MIssion History | Department of Energy

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

    systems and radioisotope heater units for NASA, Navy, Air Force, DOE. Mission Year ... Earth - Technology Demonstration Nimbus III 1969 NASA Earth - Weather Satelitte Apollo 11 ...

  12. 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.

  13. SunShot Initiative Mission | Department of Energy

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

    About the SunShot Initiative » SunShot Initiative Mission SunShot Initiative Mission Photo of a male silhouetted against a solar array. The SunShot Initiative's mission is to make solar energy fully cost-competitive with traditional energy sources before the end of this decade, making this clean renewable energy resource more affordable and accessible to Americans. Vision The SunShot Initiative vision is to make the total cost of solar energy fully economically-viable for everyday use, so that

  14. Pump Systems Matter Mission and Vision | Department of Energy

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

    Pump Systems Matter Mission and Vision Pump Systems Matter Mission and Vision Pump Systems Matter(tm) (PSM) places a primary focus on pump systems education and outreach and addresses energy savings and total cost of pump ownership. C_Vision_&_Mission_of_Pump_Systems_Matter.pdf (56.49 KB) More Documents & Publications Overview of Pump Systems Matter Hydraulic Institute Member Benefits Course Overview Pump Systems Matter Optimization

  15. Announcing "Mission Innovation" | Department of Energy

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

    Announcing "Mission Innovation" Announcing "Mission Innovation" November 29, 2015 - 7:00pm Addthis At the United Nations climate change conference in Paris, President Obama joins world leaders from 19 other countries to launch "Mission Innovation," a new initiative aimed at dramatically accelerating public and private global clean energy research and development. David Turk David Turk Deputy Assistant Secretary for International Climate and Technology Paul Bodnar

  16. 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.

  17. 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.

  18. Dark energy properties from large future galaxy surveys

    SciTech Connect (OSTI)

    Basse, Tobias; Bjlde, 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

  19. Mission

    Broader source: Energy.gov [DOE]

    Mission StatementThe EM-LA mission is to safely, efficiently, and with full transparency complete the cleanup of legacy contamination and waste resulting from nuclear weapons development and...

  20. Afghanistan-NREL Mission | Open Energy Information

    Open Energy Info (EERE)

    Company Organization National Renewable Energy Laboratory Sector Energy Focus Area Energy Efficiency, Buildings, Solar, Wind Topics Background analysis Program Start 2009...

  1. 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; Evrard, August; Jain, Bhuvnesh; Jarvis, Michael; Linder, Eric; 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

  2. Mission

    Broader source: Energy.gov [DOE]

    Office of Project Management Oversight & Assessments (PM)The primary mission of the Office of Project Management Oversight & Assessments is to provide corporate oversight, managerial...

  3. High-Powered Dark Energy Camera Can See Billions of Light Years...

    Energy Savers [EERE]

    High-Powered Dark Energy Camera Can See Billions of Light Years Away High-Powered Dark Energy Camera Can See Billions of Light Years Away August 21, 2014 - 10:19am Addthis Stars ...

  4. 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 John Hules, ...

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

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Improved Dark Energy Constraints From 100 New CfA Supernova Type Ia Light Curves Citation Details In-Document Search Title: Improved Dark Energy Constraints From ...

  6. Secure and Sustainable Energy Future Mission

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

    About Energy.gov » Leadership » Secretary of Energy Advisory Board Secretary of Energy Advisory Board Secretary of Energy Advisory Board SEAB Reports January 26, 2016 Report of the Task Force on Methane Hydrates This report presents the findings and recommendations for the Secretary of Energy Advisory Board (SEAB) Task Force on Methane Hydrates. June 17, 2015 Interim Report of the Task Force on DOE National Laboratories SEAB advice, guidance, and recommendations on important issues related to

  7. Saul Perlmutter, Distant Supernovae, Dark Energy, and the Accelerating

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

    Expansion of the Universe Saul Perlmutter, Distant Supernovae, Dark Energy, and the Accelerating Expansion of the Universe Resources with Additional Information * Awards Saul Perlmutter Photo Courtesy of Lawrence Berkeley National Laboratory 'Saul Perlmutter, an astrophysicist at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and a professor of physics at the University of California at Berkeley, has won the 2011 Nobel Prize in Physics "for the discovery of the

  8. Mission and Goals | Department of Energy

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

    Develop broadly applicable manufacturing processes that reduce energy intensity and improve production. Develop and demonstrate pervasive materials technologies, enabling improved ...

  9. 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

  10. 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.

  11. U. S. Department of Energy Savannah River Operations Office - Mission

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

    Mission Savannah River Operations Office Mission Welcome to the Savannah River Operations Office (DOE-SR) website. DOE-SR is a U.S. Department of Energy (DOE) organization that serves as the landlord for site resources and is responsible for overseeing the work performed by the Savannah River Site's (SRS) contractors. The Savannah River Site (SRS) is a key DOE industrial complex dedicated to; environmental cleanup, nuclear weapons stockpile stewardship, and nuclear materials disposition, in

  12. Cabazon Band of Mission Indians Strategic Energy Plan Presentation

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

    Cabazon Band of Mission Indians Strategic Energy Plan Presentation Prepared by Philip Rentz 11/1/2004 2 Developed for the Cabazon Band of Mission Indians (CBMI) In Cooperation With The Department of Energy 11/1/2004 3 Site Location Maps 11/1/2004 4 Tribal Land 11/1/2004 5 Fantasy Springs Resort and Casino 11/1/2004 6 Cabazon Resource Recovery Park 11/1/2004 7 Organizational Chart 11/1/2004 8 Vision Statement The primary objective of the Strategic energy Plan is to aide in the social and economic

  13. Mission

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

    - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion ...

  14. 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.

  15. Mission

    Broader source: Energy.gov [DOE]

    The mission of the U.S. Department of Energy’s Southeastern Power Administration is to market and deliver Federal hydroelectric power at the lowest possible cost to public bodies and...

  16. Mission

    Broader source: Energy.gov [DOE]

    The mission of the Office of Environmental Management (EM) is to complete the safe cleanup of the environmental legacy brought about from five decades of nuclear weapons development and government...

  17. No-Go Theorem for k-Essence Dark Energy

    SciTech Connect (OSTI)

    Bonvin, Camille; Caprini, Chiara; Durrer, Ruth

    2006-08-25

    We demonstrate that if k-essence can solve the coincidence problem and play the role of dark energy in the Universe, the fluctuations of the field have to propagate superluminally at some stage. We argue that this implies that successful k-essence models violate causality. It is not possible to define a time ordered succession of events in a Lorentz invariant way. Therefore, k-essence cannot arise as a low energy effective field theory of a causal, consistent high energy theory.

  18. 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.

  19. 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.

  20. Cleanup Mission Area Definitions | Department of Energy

    Office of Environmental Management (EM)

    California | Department of Energy Cleantech University Prize Regional Competitions Wrap Up in Florida and California Cleantech University Prize Regional Competitions Wrap Up in Florida and California June 10, 2016 - 11:25am Addthis Hosts of the Cleantech University Prize (Cleantech Up) FLoW competition with the winners, Xstream Trucking of Stanford University. The team took home the $50,000 first-place prize for their drag-reducing trucking technology. | Photo courtesy of Caltech Hosts of

  1. Inflation and dark energy from the Brans-Dicke theory

    SciTech Connect (OSTI)

    Artymowski, Michał; Lalak, Zygmunt; Lewicki, Marek

    2015-06-17

    We consider the Brans-Dicke theory motivated by the f(R)=R+αR{sup n}−βR{sup 2−n} model to obtain a stable minimum of the Einstein frame scalar potential of the Brans-Dicke field. As a result we have obtained an inflationary scalar potential with non-zero value of residual vacuum energy, which may be a source of dark energy. In addition we discuss the probability of quantum tunnelling from the minimum of the potential. Our results can be easily consistent with PLANCK or BICEP2 data for appropriate choices of the value of n and ω.

  2. 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.

  3. Mission Woods, Kansas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    article is a stub. You can help OpenEI by expanding it. Mission Woods is a city in Johnson County, Kansas. It falls under Kansas's 3rd congressional district.12 References...

  4. Mission Hills, Kansas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    article is a stub. You can help OpenEI by expanding it. Mission Hills is a city in Johnson County, Kansas. It falls under Kansas's 3rd congressional district.12 References...

  5. Mission Bend, Texas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    by expanding it. Mission Bend is a census-designated place in Fort Bend County and Harris County, Texas.1 References US Census Bureau 2005 Place to 2006 CBSA Retrieved...

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

    SciTech Connect (OSTI)

    Lima, J.A.S.; Graef, L.L.; Pavn, 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 GibbonsHawking 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.

  7. Dark Energy and Cosmic Sound Daniel Eisenstein Harvard University

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

    Dark Energy and Cosmic Sound Daniel Eisenstein Harvard University May 27, 2015 4:00 p.m. (coffee @ 3:30) Discuss how the acoustic oscillations that propagate in the photon- baryon fluid during the first million years of the Universe provide a robust method for measuring the cosmological distance scale. The distance that the sound can travel can be computed to high precision and creates a signature in the late-time clustering of matter that serves as a standard ruler. Galaxy clustering results

  8. 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.

    2011-05-06

    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 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.

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

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

    Rossetto, Bruno M.; Santiago, Baslio X.; Girardi, Lo; 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 themoreGalaxy.less

  10. The Next Dimension of Mapping the Universe: The Dark Energy Spectroscopic

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

    Instrument | Department of Energy Dimension of Mapping the Universe: The Dark Energy Spectroscopic Instrument The Next Dimension of Mapping the Universe: The Dark Energy Spectroscopic Instrument June 11, 2015 - 10:24am Addthis Zoomed-in image from the Dark Energy Camera of the barred spiral galaxy NGC 1365, in the Fornax cluster of galaxies, which lies about 60 million light years from Earth -- in other words, far, far away. | Photo courtesy of the Dark Energy Survey Collaboration. Zoomed-in

  11. 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.

  12. Holographic dark energy with varying gravitational constant in Ho?ava-Lifshitz cosmology

    SciTech Connect (OSTI)

    Setare, M.R.; Jamil, Mubasher E-mail: mjamil@camp.nust.edu.pk

    2010-02-01

    We investigate the holographic dark energy scenario with a varying gravitational constant in a flat background in the context of Ho?ava-Lifshitz gravity. We extract the exact differential equation determining the evolution of the dark energy density parameter, which includes G variation term. Also we discuss a cosmological implication of our work by evaluating the dark energy equation of state for low redshifts containing varying G corrections.

  13. Observational constraints on holographic dark energy with varying gravitational constant

    SciTech Connect (OSTI)

    Lu, Jianbo; Xu, Lixin; Saridakis, Emmanuel N.; Setare, M.R. E-mail: msaridak@phys.uoa.gr E-mail: lxxu@dlut.edu.cn

    2010-03-01

    We use observational data from Type Ia Supernovae (SN), Baryon Acoustic Oscillations (BAO), Cosmic Microwave Background (CMB) and observational Hubble data (OHD), and the Markov Chain Monte Carlo (MCMC) method, to constrain the cosmological scenario of holographic dark energy with varying gravitational constant. We consider both flat and non-flat background geometry, and we present the corresponding constraints and contour-plots of the model parameters. We conclude that the scenario is compatible with observations. In 1? we find ?{sub ?0} = 0.72{sup +0.03}{sub ?0.03}, ?{sub k0} = ?0.0013{sup +0.0130}{sub ?0.0040}, c = 0.80{sup +0.19}{sub ?0.14} and ?{sub G}?G'/G = ?0.0025{sup +0.0080}{sub ?0.0050}, while for the present value of the dark energy equation-of-state parameter we obtain w{sub 0} = ?1.04{sup +0.15}{sub ?0.20}.

  14. Mission

    Broader source: Energy.gov [DOE]

    Through strategic investments in science and technology, the U.S. Department of Energy (DOE) helps power and secure America's future. DOE's capabilities, and the innovations it supports,...

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

    SciTech Connect (OSTI)

    Magaña, Juan; Cárdenas, Víctor H.; Motta, Verónica E-mail: victor.cardenas@uv.cl

    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.

  16. Clouds at CTIO and the Dark Energy Survey

    SciTech Connect (OSTI)

    Neilsen, Jr., Eric

    2015-08-01

    An understanding of the weather patters at Cerro-Tololo Inter-American (CTIO) Observatory, the observing site for the Dark Energy Survey (DES), is important for assessing the efciency of DES operations in using observing time and for planning future operations. CTIO has maintained records of cloud-cover by quarters of nights since 1975. A comparison between these cloud records in the 2013-2014 DES observing season (DES year 1) and achieved observing efciency and exposure quality allows the DES collaboration to make better use of the historical records in survey planning. Plots and tables here relate human recorded cloud-cover to collection of good DES data, show the variation of typical cloud-cover by month, and evaluate the relationship between the El Niño weather pattern and cloud-cover at CTIO.

  17. 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

  18. 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.

  19. MissionPoint Capital Partners | Open Energy Information

    Open Energy Info (EERE)

    MissionPoint Capital Partners Jump to: navigation, search Name: MissionPoint Capital Partners Place: Norwalk, Connecticut Zip: CT 06854 Product: Private Investment company...

  20. Edison Mission Marktg & Trdg Inc | Open Energy Information

    Open Energy Info (EERE)

    Edison Mission Marktg & Trdg Inc Jump to: navigation, search Name: Edison Mission Marktg & Trdg Inc Place: Massachusetts References: EIA Form EIA-861 Final Data File for 2010 -...

  1. Dark energy: Q&A with Steve Kuhlmann | Argonne National Laboratory

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

    energy: Q&A with Steve Kuhlmann Dark energy: Q&A with Steve Kuhlmann By Jared Sagoff * September 17, 2012 Tweet EmailPrint Why do we care about dark energy in the first place? One of the most fundamental questions that scientists face is to try to figure out what the universe is made of. We know that dark energy is the largest component of the universe, accounting for about 74 percent of the mass and energy that exists combined. If we want to understand the components of the universe, we

  2. Three Ways to Bust Ghostly Dark Matter | Department of Energy

    Office of Environmental Management (EM)

    ... about two years ago. | Image courtesy of NASA. Dark Matter and a Definite Non-Definite ... waves for millennia. | Graphic courtesy of NASA When Galaxies Collide: Ripples Indicate ...

  3. Vision, Mission, and Goals | OSTI, US Dept of Energy Office of Scientific

    Office of Scientific and Technical Information (OSTI)

    and Technical Information OSTI's Vision, Mission, and Goals About OSTI Strategic Plan OSTI Vision, Mission, and Goals Catalogue of Collections Organization Chart Achievements Alliances OSTI History As detailed in the U.S. Department of Energy Office of Scientific and Technical Information 2015-2019 Strategic Plan, following are OSTI's vision, mission, and goals: Vision The Office of Scientific and Technical Information will fulfill a critical U.S. Department of Energy mission to ensure

  4. Automated transient identification in the Dark Energy Survey

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

    Goldstein, D. A.; D'Andrea, C. B.; Fischer, J. A.; Foley, R. J.; Gupta, R. R.; Kessler, R.; Kim, A. G.; Nichol, R. C.; Nungent, P.; Papadopoulos, A.; et al

    2015-09-01

    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 (2013 September through 2014 February) using the algorithm, the number of transient candidates eligible for human scanning decreased by a factormore » of 13.4, while only 1.0% of the artificial Type Ia supernovae (SNe) injected into search images to monitor survey efficiency were lost, most of which were very faint events. Furthermore, we characterize the algorithm's performance in detail, and we discuss how it can inform pipeline design decisions for future time-domain imaging surveys, such as the Large Synoptic Survey Telescope and the Zwicky Transient Facility.« less

  5. Modeling the Transfer Function for the Dark Energy Survey

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

    Chang, C.

    2015-03-04

    We present a forward-modeling 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/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) and catalogs representative of the DES data. In this work we demonstrate the framework by simulating the 244 deg2 coadd images and catalogs in five bands for the DES Science Verification data. The simulation output is compared with themore » 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 illustrate 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 modeling approach is generally applicable for other upcoming and future surveys. It provides a powerful tool for systematics studies that is sufficiently realistic and highly controllable.« less

  6. Modeling the transfer function for the Dark Energy Survey

    SciTech Connect (OSTI)

    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.

    2015-03-04

    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 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. As a result, it provides a powerful tool for systematics studies which is sufficiently realistic and highly controllable.

  7. Automated transient identification in the Dark Energy Survey

    SciTech Connect (OSTI)

    Goldstein, D. A.

    2015-08-20

    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 (2013 September through 2014 February) using the algorithm, the number of transient candidates eligible for human scanning decreased by a factor of 13.4, while only 1.0 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 surveys, such as the Large Synoptic Survey Telescope and the Zwicky Transient Facility.

  8. Automated transient identification in the Dark Energy Survey

    SciTech Connect (OSTI)

    Goldstein, D. A.; D'Andrea, C. B.; Fischer, J. A.; Foley, R. J.; Gupta, R. R.; Kessler, R.; Kim, A. G.; Nichol, R. C.; Nungent, P.; Papadopoulos, A.; Sako, M.; Smith, M.; Sullivan, M.; Thomas, R. C.; Wester, W.; Wolf, R. C.; Abdalla, F. B.; Banjeri, M.; Benoit-Levy, 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.

    2015-09-01

    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 (2013 September through 2014 February) using the algorithm, the number of transient candidates eligible for human scanning decreased by a factor of 13.4, while only 1.0% of the artificial Type Ia supernovae (SNe) injected into search images to monitor survey efficiency were lost, most of which were very faint events. Furthermore, we characterize the algorithm's performance in detail, and we discuss how it can inform pipeline design decisions for future time-domain imaging surveys, such as the Large Synoptic Survey Telescope and the Zwicky Transient Facility.

  9. Crowdsourcing quality control for Dark Energy Survey images

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

    Melchior, P.

    2016-07-01

    We have developed a crowdsourcing web application for image quality controlemployed by the Dark Energy Survey. Dubbed the "DES exposure checker", itrenders science-grade images directly to a web browser and allows users to markproblematic features from a set of predefined classes. Users can also generatecustom labels and thus help identify previously unknown problem classes. Userreports are fed back to hardware and software experts to help mitigate andeliminate recognized issues. We report on the implementation of the applicationand our experience with its over 100 users, the majority of which areprofessional or prospective astronomers but not data management experts. Wediscuss aspects ofmore » user training and engagement, and demonstrate how problemreports have been pivotal to rapidly correct artifacts which would likely havebeen too subtle or infrequent to be recognized otherwise. We conclude with anumber of important lessons learned, suggest possible improvements, andrecommend this collective exploratory approach for future astronomical surveysor other extensive data sets with a sufficiently large user base. We alsorelease open-source code of the web application and host an online demo versionat http://des-exp-checker.pmelchior.net« less

  10. Cosmic shear measurements with Dark Energy Survey Science Verification data

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

    Becker, M. R.

    2016-07-06

    Here, we present measurements of weak gravitational lensing cosmic shear two-point statistics using Dark Energy Survey Science Verification data. We demonstrate that our results are robust to the choice of shear measurement pipeline, either ngmix or im3shape, and robust to the choice of two-point statistic, including both real and Fourier-space statistics. Our results pass a suite of null tests including tests for B-mode contamination and direct tests for any dependence of the two-point functions on a set of 16 observing conditions and galaxy properties, such as seeing, airmass, galaxy color, galaxy magnitude, etc. We use a large suite of simulationsmore » to compute the covariance matrix of the cosmic shear measurements and assign statistical significance to our null tests. We find that our covariance matrix is consistent with the halo model prediction, indicating that it has the appropriate level of halo sample variance. We also compare the same jackknife procedure applied to the data and the simulations in order to search for additional sources of noise not captured by the simulations. We find no statistically significant extra sources of noise in the data. The overall detection significance with tomography for our highest source density catalog is 9.7σ. Cosmological constraints from the measurements in this work are presented in a companion paper (DES et al. 2015).« less

  11. 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 simulationmoreoutput 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

  12. Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light

    Office of Scientific and Technical Information (OSTI)

    Curves (Journal Article) | SciTech Connect Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves Citation Details In-Document Search Title: Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves We combine the CfA3 supernovae Type Ia (SN Ia) sample 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. to form the

  13. Hydraulic Institute Mission and Vision | Department of Energy

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

    Mission and Vision Hydraulic Institute Mission and Vision Mission: To be a value-adding resource to member companies and pump users worldwide by: * Developing and delivering comprehensive industry standards. * Expanding knowledge by providing education and tools for the effective application, testing, installation, operation and maintenance of pumps and pumping systems. * Serving as a forum for the exchange of industry information. B_Vision_&_Mission_of_Hydraulic_Institute.pdf (48.62 KB)

  14. Dark energy camera to probe universe's biggest mysteries | Argonne

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

    Dark Matter and a Definite Non-Definite Dark Matter and a Definite Non-Definite April 17, 2013 - 4:22pm Addthis The Alpha Magnetic Spectrometer experiment is a particle detector which was lofted to the International Space Station onboard the Space Shuttle Endeavour about two years ago. | Image courtesy of NASA. The Alpha Magnetic Spectrometer experiment is a particle detector which was lofted to the International Space Station onboard the Space Shuttle Endeavour about two years ago. | Image

  15. Observation of two new L4 Neptune Trojans in the Dark Energy...

    Office of Scientific and Technical Information (OSTI)

    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...

  16. Annealing a Follow-up Program: Improvement of the Dark Energy...

    Office of Scientific and Technical Information (OSTI)

    To this end, we apply a simulated annealing algorithm to maximize the dark energy information at fixed observational cost, and find that optimal follow-up strategies can reduce the ...

  17. Annealing a Follow-up Program: Improvement of the Dark Energy...

    Office of Scientific and Technical Information (OSTI)

    Galaxy Cluster Surveys Citation Details In-Document Search Title: Annealing a Follow-up Program: Improvement of the Dark Energy Figure of Merit for Optical Galaxy Cluster Surveys ...

  18. 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.

  19. SUPERNOVA SIMULATIONS AND STRATEGIES FOR THE DARK ENERGY SURVEY

    SciTech Connect (OSTI)

    Bernstein, J. P.; Kuhlmann, S.; Biswas, R.; Kovacs, E.; Crane, I.; Hufford, T.; Kessler, R.; Frieman, J. A.; Aldering, G.; Kim, A. G.; Nugent, P.; D'Andrea, C. B.; Nichol, R. C.; Finley, D. A.; Marriner, J.; Reis, R. R. R.; Jarvis, M. J.; Mukherjee, P.; Parkinson, D.; Sako, M.; and others

    2012-07-10

    We present an analysis of supernova light curves simulated for the upcoming Dark Energy Survey (DES) supernova search. The simulations employ a code suite that generates and fits realistic light curves in order to obtain distance modulus/redshift pairs that are passed to a cosmology fitter. We investigated several different survey strategies including field selection, supernova selection biases, and photometric redshift measurements. Using the results of this study, we chose a 30 deg{sup 2} search area in the griz filter set. We forecast (1) that this survey will provide a homogeneous sample of up to 4000 Type Ia supernovae in the redshift range 0.05

  20. Discovering the Nature of Dark Energy: Towards Better Distances from Type

    Office of Scientific and Technical Information (OSTI)

    Ia Supernovae -- Final Technical Report (Technical Report) | SciTech Connect Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae -- Final Technical Report Citation Details In-Document Search Title: Discovering the Nature of Dark Energy: Towards Better Distances from Type Ia Supernovae -- Final Technical Report Type Ia supernovae (SNe Ia; exploding white-dwarf stars) were the key to the Nobel-worthy 1998 discovery and subsequent verification that the

  1. Innovation for EM Mission Success | Department of Energy

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

    Innovation for EM Mission Success Innovation for EM Mission Success Presentation from the 2015 DOE National Cleanup Workshop by Dr. Terry Michalski, Director, Savannah River National Laboratory. Innovation for EM Mission Success (1.14 MB) More Documents & Publications PRESENTATION: OVERVIEW OF PROPOSED "DARPA-INSPIRED" APPROACH TO ENVIRONMENTAL MANAGEMENT TECHNOLOGY DEVELOPMENT PRESENTATION: OVERVIEW OF DOE OFFICE OF ENVIRONMENTAL MANAGEMENT (EM) Chairs Meeting - June 2011

  2. wh_mission_status.pdf | Department of Energy

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

    White House Mission Requests Memorandum FOIA-Summary of Findings: Circumstances surrounding decisions regarding the security clearance, access and work assignments FIA-16-0027 - In ...

  3. JOINT DEPARTMENT OF COMMERCE AND DEPARTMENT OF ENERGY SMART CITIES - SMART GROWTH BUSINESS DEVELOPMENT MISSION TO

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

    JOINT DEPARTMENT OF COMMERCE AND DEPARTMENT OF ENERGY SMART CITIES - SMART GROWTH BUSINESS DEVELOPMENT MISSION TO CHINA April 12-17, 2015 I. MISSION DESCRIPTION The United States Secretaries of Commerce Penny Pritzker and Energy Ernest Moniz will lead a Smart Cities - Smart Growth Business Development Mission to China from April 12-17, 2015. This mission was announced during President Obama's visit to China in November 2014. It will promote U.S. exports to China by supporting U.S. companies in

  4. Experimental High Energy Physics Research: Direct Detection of Dark Matter

    SciTech Connect (OSTI)

    Witherell, Michael S.

    2014-10-02

    The grant supported research on an experimental search for evidence of dark matter interactions with normal matter. The PI carried out the research as a member of the LUX and LZ collaborations. The LUX research team collected a first data set with the LUX experiment, a large liquid xenon detector installed in the Sanford Underground Research Facility (SURF). The first results were published in Physical Review Letters on March 4, 2014. The journal Nature named the LUX result a scientific highlight of the year for 2013. In addition, the LZ collaboration submitted the full proposal for the Lux Zeplin experiment, which has since been approved by DOE-HEP as a second-generation dark matter experiment. Witherell is the Level 2 manager for the Outer Detector System on the LUX-Zeplin experiment.

  5. Energy-Focused Trade Mission Will Yield Positive Effects for American

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

    Businesses and the Global Environment | Department of Energy Energy-Focused Trade Mission Will Yield Positive Effects for American Businesses and the Global Environment Energy-Focused Trade Mission Will Yield Positive Effects for American Businesses and the Global Environment April 13, 2015 - 2:35pm Addthis The joint trade mission will make stops in Beijing, Shanghai and Guangzhou. | Map by <a href="/node/712881">Daniel Wood</a>, Department of Energy. The joint trade

  6. NASA and DOE Collaborate on Dark Energy Research | U.S. DOE Office of

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

    Science (SC) 8 » NASA and DOE Collaborate on Dark Energy Research News News Home Featured Articles 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 Science Headlines Science Highlights Presentations & Testimony News Archives Communications and Public Affairs Contact Information Office of Science U.S. Department of Energy 1000 Independence Ave., SW Washington, DC 20585 P: (202) 586-5430 11.19.08 NASA and DOE Collaborate on Dark Energy Research Print Text Size: A A A Subscribe

  7. 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.

  8. 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.

  9. 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 Ω{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 γ by about 30% and 10% for the Q = γHρ{sub c} and Q = γHρ{sub de} models, respectively.

  10. Spontaneous symmetry breaking in cosmos: the hybrid symmetron as a dark energy switching device

    SciTech Connect (OSTI)

    Bamba, K.; Nojiri, S.; Gannouji, R.; Kamijo, M.; Sami, M. E-mail: gannouji@rs.kagu.tus.ac.jp E-mail: nojiri@phys.nagoya-u.ac.jp

    2013-07-01

    We consider symmetron model in a generalized background with a hope to make it compatible with dark energy. We observe a ''no go'' theorem at least in case of a conformal coupling. Being convinced of symmetron incapability to be dark energy, we try to retain its role for spontaneous symmetry breaking and assign the role of dark energy either to standard quintessence or F(R) theory which are switched on by symmetron field in the symmetry broken phase. The scenario reduces to standard Einstein gravity in the high density region. After the phase transition generated by symmetron field, either the F(R) gravity or the standard quintessence are induced in the low density region. we demonstrate that local gravity constraints and other requirements are satisfied although the model could generate the late-time acceleration of Universe.

  11. Dark Matter Theory

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

    Dark Matter Theory Dark Matter Theory Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email Bruce Carlsten (505) ...

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

    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 John Hules, JAHules@lbl.gov, +1 510 486 6008 "If NERSC does not enable a major scientific discovery every few years, then we're not doing our job." That was the challenge issued by Bill McCurdy, then Lawrence Berkeley National Laboratory's Associate Laboratory Director for Computing Sciences, at the first all-hands meeting for

  13. 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.

  14. Augustine Band of Cahuilla Mission Indians - Energy Conservation...

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

    ... * Design and prepare bid packages for alternative energy development project. ... for similar land uses? * How should we forecast and measure the energy and other ...

  15. NERSC Mission

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

    Mission NERSC Mission The mission of the National Energy Research Scientific Computing Center (NERSC) is to accelerate scientific discovery at the DOE Office of Science through high performance computing and data analysis. NERSC is the principal provider of high performance computing services to Office of Science programs - Magnetic Fusion Energy, High Energy Physics, Nuclear Physics, Basic Energy Sciences, Biological and Environmental Research, and Advanced Scientific Computing Research.

  16. SunShot Initiative Mission | Department of Energy

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

    The SunShot Initiative vision is to make the total cost of solar energy fully economically-viable for everyday use, so that all Americans will benefit from this clean renewable energy ...

  17. Campo Band of Mission Indians - Renewable Energy Update

    Energy Savers [EERE]

    Redefine governments in State law to allow "pooling" of net meter benefit ... Microeconomic analyses on renewable energy in context of regional tax revenue sources and ...

  18. Augustine Band of Cahuilla Mission Indians - Energy Conservation...

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

    ... alternatives? * As among developers, end users and the Tribe, how should the cost ... CURRENT ENERGY USAGE * Casino Electricity consumption - Current 571,500 KWhmo. - Projected ...

  19. New Airborne Technology Measures Ocean Surface Currents for Offshore Energy Production and Emergency Rescue Missions

    Broader source: Energy.gov [DOE]

    In a breakthrough project sponsored by the Energy Department’s National Energy Technology Laboratory (NETL), private-sector partners Fugro and Areté Associates have developed, commercialized, and sold a system that can monitor offshore current conditions from the air, providing critical information in record time for oceanographic research and emergency situations, such as oil spills and search and rescue missions.

  20. Mission Statement

    Broader source: Energy.gov [DOE]

    Our mission is to remove environmental legacies resulting from more than 60 years nuclear weapons development and government-sponsored nuclear energy research.

  1. OSTI's Vision, Mission, and Goals | OSTI, US Dept of Energy,...

    Office of Scientific and Technical Information (OSTI)

    | OSTI History As detailed in the U.S. Department of Energy Office of Scientific ... The Office of Scientific and Technical Information will fulfill a critical U.S. Department ...

  2. DOE Success Stories: The Energy Mission in the Marketplace

    DOE R&D Accomplishments [OSTI]

    1995-05-01

    Many outputs of Department of Energy research and development have had substantial economic success in the marketplace and have proven to be fundamentally important in technical areas, positioning U.S. industry at the forefront of global competition.

  3. Observation of two new L4 Neptune Trojans in the Dark Energy Survey supernova fields

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

    Gerdes, D. W.

    2016-01-28

    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-termmore » dynamical stability and physical properties.« less

  4. 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.

  5. Energy from the Center of the Milky Way May Be the Remnant of Dark Matter |

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

    U.S. DOE Office of Science (SC) Energy from the Center of the Milky Way May Be the Remnant of Dark Matter News News Home Featured Articles 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 Science Headlines Science Highlights Presentations & Testimony News Archives Communications and Public Affairs Contact Information Office of Science U.S. Department of Energy 1000 Independence Ave., SW Washington, DC 20585 P: (202) 586-5430 11.17.10 Energy from the Center of the Milky Way May

  6. 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.

  7. Testing oscillating primordial spectrum and oscillating dark energy with astronomical observations

    SciTech Connect (OSTI)

    Liu, Jie; Li, Hong; Zhang, Xinmin; Xia, Jun-Qing E-mail: hongli@ihep.ac.cn E-mail: xmzhang@ihep.ac.cn

    2009-07-01

    In this paper we revisit the issue of determining the oscillating primordial scalar power spectrum and oscillating equation of state of dark energy from the astronomical observations. By performing a global analysis with the Markov Chain Monte Carlo method, we find that the current observations from five-year WMAP and SDSS-LRG matter power spectrum, as well as the ''union'' supernovae sample, constrain the oscillating index of primordial spectrum and oscillating equation of state of dark energy with the amplitude less than |n{sub amp}| < 0.116 and |w{sub amp}| < 0.232 at 95% confidence level, respectively. This result shows that the oscillatory structures on the primordial scalar spectrum and the equation of state of dark energy are still allowed by the current data. Furthermore, we point out that these kinds of modulation effects will be detectable (or gotten a stronger constraint) in the near future astronomical observations, such as the PLANCK satellite, LAMOST telescope and the currently ongoing supernovae projects SNLS.

  8. Crowded Cluster Cores. Algorithms for Deblending in Dark Energy Survey Images

    SciTech Connect (OSTI)

    Zhang, Yuanyuan; McKay, Timothy A.; Bertin, Emmanuel; Jeltema, Tesla; Miller, Christopher J.; Rykoff, Eli; Song, Jeeseon

    2015-10-26

    Deep optical images are often crowded with overlapping objects. We found that this is especially true in the cores of galaxy clusters, where images of dozens of galaxies may lie atop one another. Accurate measurements of cluster properties require deblending algorithms designed to automatically extract a list of individual objects and decide what fraction of the light in each pixel comes from each object. In this article, we introduce a new software tool called the Gradient And Interpolation based (GAIN) deblender. GAIN is used as a secondary deblender to improve the separation of overlapping objects in galaxy cluster cores in Dark Energy Survey images. It uses image intensity gradients and an interpolation technique originally developed to correct flawed digital images. Our paper is dedicated to describing the algorithm of the GAIN deblender and its applications, but we additionally include modest tests of the software based on real Dark Energy Survey co-add images. GAIN helps to extract an unbiased photometry measurement for blended sources and improve detection completeness, while introducing few spurious detections. When applied to processed Dark Energy Survey data, GAIN serves as a useful quick fix when a high level of deblending is desired.

  9. The dark energy cosmic clock: a new way to parametrise the equation of state

    SciTech Connect (OSTI)

    Tarrant, Ewan R.M.; Copeland, Edmund J.; Padilla, Antonio; Skordis, Constantinos E-mail: ed.copeland@nottingham.ac.uk E-mail: skordis@nottingham.ac.uk

    2013-12-01

    We propose a new parametrisation of the dark energy equation of state, which uses the dark energy density, Ω{sub e} as a cosmic clock. We expand the equation of state in a series of orthogonal polynomials, with Ω{sub e} as the expansion parameter and determine the expansion coefficients by fitting to SNIa and H(z) data. Assuming that Ω{sub e} is a monotonic function of time, we show that our parametrisation performs better than the popular Chevallier-Polarski-Linder (CPL) and Gerke and Efstathiou (GE) parametrisations, and we demonstrate that it is robust to the choice of prior. Expanding in orthogonal polynomials allows us to relate models of dark energy directly to our parametrisation, which we illustrate by placing constraints on the expansion coefficients extracted from two popular quintessence models. Finally, we comment on how this parametrisation could be modified to accommodate high redshift data, where any non-monotonicity of Ω{sub e} would need to be accounted for.

  10. Crowded Cluster Cores. Algorithms for Deblending in Dark Energy Survey Images

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

    Zhang, Yuanyuan; McKay, Timothy A.; Bertin, Emmanuel; Jeltema, Tesla; Miller, Christopher J.; Rykoff, Eli; Song, Jeeseon

    2015-10-26

    Deep optical images are often crowded with overlapping objects. We found that this is especially true in the cores of galaxy clusters, where images of dozens of galaxies may lie atop one another. Accurate measurements of cluster properties require deblending algorithms designed to automatically extract a list of individual objects and decide what fraction of the light in each pixel comes from each object. In this article, we introduce a new software tool called the Gradient And Interpolation based (GAIN) deblender. GAIN is used as a secondary deblender to improve the separation of overlapping objects in galaxy cluster cores inmore » Dark Energy Survey images. It uses image intensity gradients and an interpolation technique originally developed to correct flawed digital images. Our paper is dedicated to describing the algorithm of the GAIN deblender and its applications, but we additionally include modest tests of the software based on real Dark Energy Survey co-add images. GAIN helps to extract an unbiased photometry measurement for blended sources and improve detection completeness, while introducing few spurious detections. When applied to processed Dark Energy Survey data, GAIN serves as a useful quick fix when a high level of deblending is desired.« less

  11. 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.

  12. 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, Ane 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.

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

    SciTech Connect (OSTI)

    Zhang, Jing-Fei; Geng, Jia-Jia; Zhang, Xin E-mail: gengjiajia163@163.com

    2014-10-01

    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 ΛCDM 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 wCDM r ∑ m{sub ν}, wCDM r N{sub eff}, wCDM r ∑ m{sub ν} N{sub eff}, and wCDM r N{sub eff} m{sub ν,sterile}{sup eff} models. The current observational data considered in this paper include the Planck temperature data, the WMAP 9-year polarization data, the baryon acoustic oscillation data, the Hubble constant direct measurement data, the Planck Sunyaev-Zeldovich cluster counts data, the Planck CMB lensing data, the cosmic shear data, and the BICEP2 polarization data. We test the data consistency in the four cosmological models, and then combine the consistent data sets to perform joint constraints on the models. We focus on the constraints on the parameters w, ∑ m{sub ν}, N{sub eff}, and m{sub ν,sterile}{sup eff}.

  14. OSTIblog Articles in the mission Topic | OSTI, US Dept of Energy Office of

    Office of Scientific and Technical Information (OSTI)

    Scientific and Technical Information mission Topic The National Library of Energy(Beta): A Gateway to Information about the "All-of-the-Above" Energy Strategy by Dr. Jeffrey Salmon 26 Sep, 2013 in Science Communications 10222 NLE_logo_ostiblog2.png The National Library of Energy(Beta): A Gateway to Information about the "All-of-the-Above" Energy Strategy Read more about 10222 While I have not taken a formal survey, my experience over many years as a Department of Energy

  15. Combined cosmological tests of a bivalent tachyonic dark energy scalar field model

    SciTech Connect (OSTI)

    Keresztes, Zoltán; Gergely, László Á. E-mail: gergely@physx.u-szeged.hu

    2014-11-01

    A recently investigated tachyonic scalar field dark energy dominated universe exhibits a bivalent future: depending on initial parameters can run either into a de Sitter exponential expansion or into a traversable future soft singularity followed by a contraction phase. We also include in the model (i) a tiny amount of radiation, (ii) baryonic matter (Ω{sub b}h{sup 2} = 0.022161, where the Hubble constant is fixed as h = 0.706) and (iii) cold dark matter (CDM). Out of a variety of six types of evolutions arising in a more subtle classification, we identify two in which in the past the scalar field effectively degenerates into a dust (its pressure drops to an insignificantly low negative value). These are the evolutions of type IIb converging to de Sitter and type III hitting the future soft singularity. We confront these background evolutions with various cosmological tests, including the supernova type Ia Union 2.1 data, baryon acoustic oscillation distance ratios, Hubble parameter-redshift relation and the cosmic microwave background (CMB) acoustic scale. We determine a subset of the evolutions of both types which at 1σ confidence level are consistent with all of these cosmological tests. At perturbative level we derive the CMB temperature power spectrum to find the best agreement with the Planck data for Ω{sub CDM} = 0.22. The fit is as good as for the ΛCDM model at high multipoles, but the power remains slightly overestimated at low multipoles, for both types of evolutions. The rest of the CDM is effectively generated by the tachyonic field, which in this sense acts as a combined dark energy and dark matter model.

  16. Supernovae, Dark Energy and the Accelerating Universe: How DOE Helped to Win (yet another) Nobel Prize

    SciTech Connect (OSTI)

    Perlmutter, Saul

    2012-01-13

    The Department of Energy (DOE) hosted an event Friday, January 13, with 2011 Physics Nobel Laureate Saul Perlmutter. Dr. Perlmutter, a physicist at the Departments Lawrence Berkeley National Laboratory and a professor of physics at the University of California at Berkeley, won the 2011 Nobel Prize in Physics for the discovery of the accelerating expansion of the Universe through observations of distant supernovae. DOEs Office of Science has supported Dr. Perlmutters research at Berkeley Lab since 1983. After the introduction from Secretary of Energy Steven Chu, Dr. Perlmutter delivered a presentation entitled "Supernovae, Dark Energy and the Accelerating Universe: How DOE Helped to Win (yet another) Nobel Prize." [Copied with editing from DOE Media Advisory issued January 10th, found at http://energy.gov/articles/energy-department-host-event-2011-physics-nobel-laureate-saul-perlmutter

  17. Supernovae, Dark Energy and the Accelerating Universe: How DOE Helped to Win (yet another) Nobel Prize

    ScienceCinema (OSTI)

    Perlmutter, Saul

    2012-01-13

    The Department of Energy (DOE) hosted an event Friday, January 13, with 2011 Physics Nobel Laureate Saul Perlmutter. Dr. Perlmutter, a physicist at the Department?s Lawrence Berkeley National Laboratory and a professor of physics at the University of California at Berkeley, won the 2011 Nobel Prize in Physics ?for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.? DOE?s Office of Science has supported Dr. Perlmutter?s research at Berkeley Lab since 1983. After the introduction from Secretary of Energy Steven Chu, Dr. Perlmutter delivered a presentation entitled "Supernovae, Dark Energy and the Accelerating Universe: How DOE Helped to Win (yet another) Nobel Prize." [Copied with editing from DOE Media Advisory issued January 10th, found at http://energy.gov/articles/energy-department-host-event-2011-physics-nobel-laureate-saul-perlmutter

  18. Houston Visit Highlights People and Programs Helping the Office of Fossil Energy Fulfill Its Mission

    Office of Energy Efficiency and Renewable Energy (EERE)

    When I joined the Office of Fossil Energy as Deputy Assistant Secretary for Oil and Natural Gas this past September, three areas made an immediate impression: the office’s highly innovative research and development portfolio; the expertise of FE staff and their collaborative, constructive relationship with industry, state, international and academic research partners; and how the mission of FE in general, and ONG in particular, is essential to developing a secure, sustainable and clean energy future.

  19. 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 6.8σ 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

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

    SciTech Connect (OSTI)

    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 6.8σ level with 20 arc min smoothing. These 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.

  1. MODEL-INDEPENDENT EVIDENCE FOR DARK ENERGY EVOLUTION FROM BARYON ACOUSTIC OSCILLATIONS

    SciTech Connect (OSTI)

    Sahni, V.; Shafieloo, A.; Starobinsky, A. A. E-mail: arman@apctp.org

    2014-10-01

    Baryon acoustic oscillations (BAOs) allow us to determine the expansion history of the universe, thereby shedding light on the nature of dark energy. Recent observations of BAOs in the Sloan Digital Sky Survey (SDSS) DR9 and DR11 have provided us with statistically independent measurements of H(z) at redshifts of 0.57 and 2.34, respectively. We show that these measurements can be used to test the cosmological constant hypothesis in a model-independent manner by means of an improved version of the Om diagnostic. Our results indicate that the SDSS DR11 measurement of H(z) = 222 ± 7 km s{sup –1} Mpc{sup –1} at z = 2.34, when taken in tandem with measurements of H(z) at lower redshifts, imply considerable tension with the standard ΛCDM model. Our estimation of the new diagnostic Omh {sup 2} from SDSS DR9 and DR11 data, namely, Omh {sup 2} ≈ 0.122 ± 0.01, which is equivalent to Ω{sub 0m} h {sup 2} for the spatially flat ΛCDM model, is in tension with the value Ω{sub 0m} h {sup 2} = 0.1426 ± 0.0025 determined for ΛCDM from Planck+WP. This tension is alleviated in models in which the cosmological constant was dynamically screened (compensated) in the past. Such evolving dark energy models display a pole in the effective equation of state of dark energy at high redshifts, which emerges as a smoking gun test for these theories.

  2. Constraints on a f(R) gravity dark energy model with early scaling evolution

    SciTech Connect (OSTI)

    Park, Chan-Gyung; Hwang, Jai-chan; Noh, Hyerim E-mail: jchan@knu.ac.kr

    2011-09-01

    The modified gravity with f(R) = R{sup 1+?} (? > 0) allows a scaling solution where the energy density of gravity sector follows the energy density of the dominant fluid. We present initial conditions of background and perturbation variables during the scaling evolution regime in the modified gravity. As a possible dark energy model we consider a gravity with a form f(R) = R{sup 1+?}+qR{sup ?n} (?1 < n ? 0) where the second term drives the late-time acceleration. We show that our f(R) gravity parameters are very sensitive to the baryon perturbation growth and baryon density power spectrum, and present observational constraints on the model parameters. We consider full perturbations of f(R) gravity. Our analysis suggests that only the parameter space extremely close to the ?CDM model is allowed with ??<5 10{sup ?6} and n?>?10{sup ?4}.

  3. Cosmological back-reaction in modified gravity and its implications for dark energy

    SciTech Connect (OSTI)

    Preston, Anthony W.H.; Morris, Tim R. E-mail: T.R.Morris@soton.ac.uk

    2014-09-01

    We study the effective stress-energy tensor induced by cosmological inhomogeneity in f(R)=R+c R{sup 2} and equivalent scalar-tensor theories, motivated both by models of early universe inflation and by phenomenological alternative cosmologies to the standard Λ-CDM. We use Green and Wald's framework for averaging over classical fluctuations of short-wavelength λ. By ensuring that the leading non-linear terms from the fluctuations of the Einstein terms and the corrections both contribute in the formal limit as λ→0, we derive a diffeomorphism invariant effective stress-energy tensor whose trace is non-vanishing and of the right sign to potentially account for the current acceleration of the universe. However a more phenomenologically acceptable dark energy model would be required if this effect were to fully account for the current acceleration.

  4. Maps of CMB lensing deflection from N-body simulations in Coupled Dark Energy Cosmologies

    SciTech Connect (OSTI)

    Carbone, Carmelita; Baldi, Marco; Baccigalupi, Carlo E-mail: marco.baldi5@unibo.it E-mail: bacci@sissa.it

    2013-09-01

    We produce lensing potential and deflection-angle maps in order to simulate the weak gravitational lensing of the Cosmic Microwave Background (CMB) via ray-tracing through the COupled Dark Energy Cosmological Simulations (CoDECS), the largest suite of N-body simulations to date for interacting Dark Energy cosmologies. The constructed maps faithfully reflect the N-body cosmic structures on a range of scales going from the arcminute to the degree scale, limited only by the resolution and extension of the simulations. We investigate the variation of the lensing pattern due to the underlying Dark Energy (DE) dynamics, characterised by different background and perturbation behaviours as a consequence of the interaction between the DE field and Cold Dark Matter (CDM). In particular, we study in detail the results from three cosmological models differing in the background and perturbations evolution at the epoch in which the lensing cross section is most effective, corresponding to a redshift of ∼ 1, with the purpose to isolate their imprints in the lensing observables, regardless of the compatibility of these models with present constraints. The scenarios investigated here include a reference ΛCDM cosmology, a standard coupled DE (cDE) scenario, and a ''bouncing'' cDE scenario. For the standard cDE scenario, we find that typical differences in the lensing potential result from two effects: the enhanced growth of linear CDM density fluctuations with respect to the ΛCDM case, and the modified nonlinear dynamics of collapsed structures induced by the DE-CDM interaction. As a consequence, CMB lensing highlights the DE impact in the cosmological expansion, even in the degenerate case where the amplitude of the linear matter density perturbations, parametrised through σ{sub 8}, is the same in both the standard cDE and ΛCDM cosmologies. For the ''bouncing'' scenario, we find that the two opposite behaviours of the lens density contrast and of the matter abundance lead to

  5. DOC-DOE China Mission Announcement Press Release | Department of Energy

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

    China Mission Announcement Press Release DOC-DOE China Mission Announcement Press Release DOC-DOE China Mission Announcement Press Release DOC-DOE China Mission Announcement Press Release (34.5 KB) More Documents & Publications DOC-DOE Joint China Mission Statement China 2015 Business Development Mission Marketing Flyer DOE-LPO_Email-Update_001_Through_11

  6. DESAlert: Enabling real-time transient follow-up with Dark Energy Survey data

    SciTech Connect (OSTI)

    Poci, A.

    2015-04-12

    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 redshifts) of potential GRB host galaxies. We provide the functional details of the DESAlert software as it presently operates, as well as the data products that it produces, and we show sample results from the application of DESAlert to several previously-detected GRBs.

  7. Detecting features in the dark energy equation of state: a wavelet approach

    SciTech Connect (OSTI)

    Hojjati, Alireza; Pogosian, Levon; Zhao, Gong-Bo E-mail: levon@sfu.ca

    2010-04-01

    We study the utility of wavelets for detecting the redshift evolution of the dark energy equation of state w(z) from the combination of supernovae (SNe), CMB and BAO data. We show that local features in w, such as bumps, can be detected efficiently using wavelets. To demonstrate, we first generate a mock supernovae data sample for a SNAP-like survey with a bump feature in w(z) hidden in, then successfully discover it by performing a blind wavelet analysis. We also apply our method to analyze the recently released ''Constitution'' SNe data, combined with WMAP and BAO from SDSS, and find weak hints of dark energy dynamics. Namely, we find that models with w(z) < −1 for 0.2 < z < 0.5, and w(z) > −1 for 0.5 < z < 1, are mildly favored at 95% confidence level. This is in good agreement with several recent studies using other methods, such as redshift binning with principal component analysis (PCA) (e.g. Zhao and Zhang, arXiv: 0908.1568)

  8. 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

    2015-07-29

    The Australian Dark Energy Survey (OzDES) is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim is to measure redshifts of approximately 2500 Type Ia supernovae host galaxies over the redshift range 0.1 < z < 1.2, and derive reverberation-mapped black hole masses for approximately 500 active galactic nuclei and quasars over 0.3 < z < 4.5. This treasure trove of data forms a major part of the spectroscopic follow-up for the Dark Energy Survey for which we are also targeting cluster galaxies, radio galaxies, strong lenses, and unidentified transients, as well as measuring luminous red galaxiesmore » and emission line galaxies to help calibrate photometric redshifts. Here, we present an overview of the OzDES programme and our first-year results. Between 2012 December and 2013 December, 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. In conclusion, 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

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

    SciTech Connect (OSTI)

    Yuan, Fang

    2015-07-29

    The Australian Dark Energy Survey (OzDES) is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim is to measure redshifts of approximately 2500 Type Ia supernovae host galaxies over the redshift range 0.1 < z < 1.2, and derive reverberation-mapped black hole masses for approximately 500 active galactic nuclei and quasars over 0.3 < z < 4.5. This treasure trove of data forms a major part of the spectroscopic follow-up for the Dark 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 programme and our first-year results. Between 2012 December and 2013 December, 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. In conclusion, 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.

  10. Constraining dark matter late-time energy injection: decays and p-wave annihilations

    SciTech Connect (OSTI)

    Diamanti, Roberta; Mena, Olga; Palomares-Ruiz, Sergio; Vincent, Aaron C.; Lopez-Honorez, Laura E-mail: llopezho@vub.ac.be E-mail: sergio.palomares.ruiz@ific.uv.es

    2014-02-01

    We use the latest cosmic microwave background (CMB) observations to provide updated constraints on the dark matter lifetime as well as on p-wave suppressed annihilation cross sections in the 1 MeV to 1 TeV mass range. In contrast to scenarios with an s-wave dominated annihilation cross section, which mainly affect the CMB close to the last scattering surface, signatures associated with these scenarios essentially appear at low redshifts (z∼<50) when structure began to form, and thus manifest at lower multipoles in the CMB power spectrum. We use data from Planck, WMAP9, SPT and ACT, as well as Lyman–α measurements of the matter temperature at z ∼ 4 to set a 95% confidence level lower bound on the dark matter lifetime of ∼ 4 × 10{sup 25} s for m{sub χ} = 100 MeV. This bound becomes lower by an order of magnitude at m{sub χ} = 1 TeV due to inefficient energy deposition into the intergalactic medium. We also show that structure formation can enhance the effect of p-wave suppressed annihilation cross sections by many orders of magnitude with respect to the background cosmological rate, although even with this enhancement, CMB constraints are not yet strong enough to reach the thermal relic value of the cross section.

  11. Mission, Vision, Values

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

    About Energy.gov » Mission Mission The mission of the Energy Department is to ensure America's security and prosperity by addressing its energy, environmental and nuclear challenges through transformative science and technology solutions. Energy Catalyze the timely, material, and efficient transformation of the nation's energy system and secure U.S. leadership in clean energy technologies. Learn more Topics Energy Economy Energy Efficiency Energy Sources Energy Usage Science & Innovation

  12. Lyman Alpha Emitting Galaxies at 2 < z < 3: Towards a Calibrated Probe of Dark Energy

    SciTech Connect (OSTI)

    Caryl Gronwall

    2012-12-03

    The goal of this project was to establish the physical properties of Ly{alpha} emitting galaxies from redshifts of 2 to 3 in order to better calibrate the use of LAEs as probes of the large scale structure of the universe for upcoming dark energy experiments, such as the Hobby Eberly Telescope Dark Energy Experiment (HETDEX). We have obtained narrow-band imaging of the Extended Chandra Deep Field South (ECDF-S) in two different narrow-band filters centered at Ly{alpha} at z=2.1 and 3.1. The resulting of samples of LAEs were used to determine the LAE luminosity function, equivalent width distribution and clustering properties (bias) of LAEs at these redshifts. While the results from the ECDF-S appear robust, they are based on a single field. To explore the effects of cosmic variance and galaxy environment on the physical properties of LAEs, we have also obtained narrow-band data at both redshifts (z = 2:1 and 3:1) in three additional fields (SDSS 1030+-05, the Extended Hubble Deep Field South, and CW 1255+01). The narrow-band imaging data has been reduced and LAE catalogs are being generated. We have calculated preliminary luminosity functions, equivalent width distributions, and clustering properties. We have also obtained follow-up spectroscopy in the optical (using VLT/FORS) and in the near-infrared (using Magellan/MMIRS). Since individual LAEs have too little S/N to enable meaningful fits for stellar population parameters, our previous work has analyzed stacked Spectral Energy Distributions (SEDs). SED fitting was performed on several subsets of LAEs selected by their rest-UV luminosity, UV spectral slope, Ly alpha luminosity, Equivalent Width, or rest-optical (IRAC) luminosity.

  13. U.S. Department of Energy, Richland Operations Office And Mission Support Alliance, LLC Partnering Charter For Partnering Performance Agreement

    Broader source: Energy.gov [DOE]

    The U.S. Department of Energy, Richland Operations Office (DOE-RL) and the Mission Support Alliance, LLC (MSA) are committed to continuous improvement and will partner together to enchance teaming...

  14. Phantom of the Hartle–Hawking instanton: Connecting inflation with dark energy

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

    Chen, Pisin; Qiu, Taotao; Yeom, Dong -han

    2016-02-20

    If the Hartle–Hawking wave function is the correct boundary condition of our universe, the history of our universe will be well approximated by an instanton. Although this instanton should be classicalized at infinity, as long as we are observing a process of each history, we may detect a non-classicalized part of field combinations. When we apply it to a dark energy model, this non-classicalized part of fields can be well embedded to a quintessence and a phantom model, i.e., a quintom model. Because of the property of complexified instantons, the phantomness will be naturally free from a big rip singularity.more » This phantomness does not cause perturbative instabilities, as it is an effect emergent from the entire wave function. Lastly, our work may thus provide a theoretical basis for the quintom models, whose equation of state can cross the cosmological constant boundary phenomenologically.« less

  15. Quantum fate of singularities in a dark-energy dominated universe

    SciTech Connect (OSTI)

    Bouhmadi-Lopez, Mariam; Kiefer, Claus; Sandhoefer, Barbara; Moniz, Paulo Vargas

    2009-06-15

    Classical models for dark energy can exhibit a variety of singularities, many of which occur for scale factors much bigger than the Planck length. We address here the issue of whether some of these singularities, the big freeze and the big demarrage, can be avoided in quantum cosmology. We use the framework of quantum geometrodynamics. We restrict our attention to a class of models whose matter content can be described by a generalized Chaplygin gas and be represented by a scalar field with an appropriate potential. Employing the DeWitt criterion that the wave function be zero at the classical singularity, we show that a class of solutions to the Wheeler-DeWitt equation fulfilling this condition can be found. These solutions thus avoid the classical singularity. We discuss the reasons for the remaining ambiguity in fixing the solution.

  16. Constraints on dark energy from new observations including Pan-STARRS

    SciTech Connect (OSTI)

    Zheng, Wei [Department of Physics, Nanjing University, Nanjing, 210093 China (China); Li, Si-Yu [Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Science, P.O. Box 918-4, Beijing, 100049 (China); Li, Hong; Xia, Jun-Qing [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Science, P.O. Box 918-3, Beijing, 100049 (China); Li, Mingzhe [Interdisciplinary Center for Theoretical Study, University of Science and Technology of China, Hefei, Anhui, 230026 China (China); Lu, Tan, E-mail: physicsweiwei@gmail.com, E-mail: lisy@ihep.ac.cn, E-mail: hongli@ihep.ac.cn, E-mail: xiajq@ihep.ac.cn, E-mail: limz@ustc.edu.cn, E-mail: t.lu@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, 210008 China (China)

    2014-08-01

    In this paper, we set the new limits on the equation of state parameter (EoS) of dark energy with the observations of cosmic microwave background radiation (CMB) from Planck satellite, the type Ia supernovae from Pan-STARRS and the baryon acoustic oscillation (BAO). We consider two parametrization forms of EoS: a constant w and time evolving w(a)=w{sub 0}+w{sub a}(1-a). The results show that with a constant EoS, w=-1.1410.075 68% C.L.), which is consistent with ?CDM at about 2? confidence level. For a time evolving w(a) model, we get w{sub 0}=-1.09{sup +0.16}{sub -0.18} 1? C.L.), w{sub a}=-0.34{sup +0.87}{sub -0.51} 1? C.L.), and in this case ?CDM can be comparable with our observational data at 1? confidence level. In order to do the parametrization independent analysis, additionally we adopt the so called principal component analysis (PCA) method, in which we divide redshift range into several bins and assume w as a constant in each redshift bin (bin-w). In such bin-w scenario, we find that for most of the bins cosmological constant can be comparable with the data, however, there exists few bins which give w deviating from ?CDM at more than 2? confidence level, which shows a weak hint for the time evolving behavior of dark energy. To further confirm this hint, we need more data with higher precision.

  17. Solar-energy an American India (SAI) partnership: The Ramakrishna Mission PV Project

    SciTech Connect (OSTI)

    Ullal, H.S.; Stone, J.L.

    1997-12-01

    This paper describes a cooperative program which was established in 1993 by the Minister of the Indian Ministry of Non-Conventional Energy Sources (MNES) and the Secretary of the U.S. Department of Energy (USDOE). Eventually it fielded one project, funded 50-50 for a total of 500k dollars. The project selected was a sustainable rural economic development initiative with Ramakrishna Mission in West Bengal, India, as the nongovernment organization (NGO). The objectives of the program were to establish the economic viability of photovoltaic power in the Sundarbans region of West Bengal. To have the project self-sustaining with minimal subsidies to the beneficiaries. To establish the infrastructure for financing, training, installation and maintenance with the NGO taking the lead. To work with the NGO to expand utilization of photovoltaics in the region. To perform a before and after social, economic, and environmental impact study with the Tata Energy Research Institute.

  18. Morongo Band of Mission Indians - Southwest Tribal Energy Consortium's Renewable Energy Project

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

    Review Meeting Denver Colorado November 8, 2007 Southwest Tribal Energy Consortium 2 Discussion Outline Participants Development of Business Strategy Native Spirit Solar I Development phases CSP technology options Project Concept Project location for Native Spirit Solar I Project Status 3 *Advisors: Council Of Energy Resource Tribes (CERT) *Initial Funding: Department of Energy - Tribal Energy Program *Technology Advisors: National Renewable Energy Lab CSP Program *Primary Consultant: Red

  19. Morongo Band of Mission Indians - Southwest Tribal Energy Consortiums Renewable Energy Project

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

    Southwest Tribal Energy Consortium Renewable Energy Feasibility Study U.S. Department of Energy Tribal Energy Program Review Todd Hooks, SWTEC Member, Agua Caliente Band of Cahuilla Indians Carolyn Stewart, Red Mountain Energy Partners October 2006 1 © 2006 All Rights Reserved Discussion Outline 1 Project Overview 2 Project Location 3 Project Participants 4 Project Status 5 Next Steps Project Overview 2 © 2006 All Rights Reserved Project Overview >> Background Feasibility study to

  20. Constraining dark energy models using the lookback time to galaxy clusters and the age of the universe

    SciTech Connect (OSTI)

    Capozziello, S.; Cardone, V.F.; Funaro, M.; Andreon, S.

    2004-12-15

    An impressive amount of different astrophysical data converges towards the picture of a spatially flat Universe undergoing today a phase of accelerated expansion. The nature of the dark energy dominating the energy content of the Universe is still unknown, and a lot of different scenarios are viable candidates to explain cosmic acceleration. Most of the methods employed to test these cosmological models are essentially based on distance measurements to a particular class of objects. A different method, based on the lookback time to galaxy clusters and the age of the Universe, is used here. In particular, we constrain the characterizing parameters of three classes of dark energy cosmological models to see whether they are in agreement with this kind of data, based on time measurements rather than distance observations.

  1. 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

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

    SciTech Connect (OSTI)

    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 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 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

  3. New Constraints on Dark Energy from Chandra X-rayObservations of the Largest Relaxed Galaxy Clusters

    SciTech Connect (OSTI)

    Allen, S.W.; Rapetti, D.A.; /KIPAC, Menlo Park; Schmidt, R.W.; /Heidelberg, Astron. Rechen Inst.; Ebeling, H.; /Inst. Astron., Honolulu; Morris, G.; /KIPAC, Menlo Park; Fabian, A.C.; /Cambridge U., Inst. of Astron.

    2007-06-06

    We present constraints on the mean matter density, {Omega}{sub m}, dark energy density, {Omega}{sub DE}, and the dark energy equation of state parameter, w, using Chandra measurements of the X-ray gas mass fraction (fgas) in 42 hot (kT > 5keV), X-ray luminous, dynamically relaxed galaxy clusters spanning the redshift range 0.05 < z < 1.1. Using only the fgas data for the 6 lowest redshift clusters at z < 0.15, for which dark energy has a negligible effect on the measurements, we measure {Omega}{sub m}=0.28{+-}0.06 (68% confidence, using standard priors on the Hubble Constant, H{sub 0}, and mean baryon density, {Omega}{sub b}h{sup 2}). Analyzing the data for all 42 clusters, employing only weak priors on H{sub 0} and {Omega}{sub b}h{sup 2}, we obtain a similar result on {Omega}{sub m} and detect the effects of dark energy on the distances to the clusters at {approx}99.99% confidence, with {Omega}{sub DE}=0.86{+-}0.21 for a non-flat LCDM model. The detection of dark energy is comparable in significance to recent SNIa studies and represents strong, independent evidence for cosmic acceleration. Systematic scatter remains undetected in the f{sub gas} data, despite a weighted mean statistical scatter in the distance measurements of only {approx}5%. For a flat cosmology with constant w, we measure {Omega}{sub m}=0.28{+-}0.06 and w=-1.14{+-}0.31. Combining the fgas data with independent constraints from CMB and SNIa studies removes the need for priors on {Omega}{sub b}h{sup 2} and H{sub 0} and leads to tighter constraints: {Omega}{sub m}=0.253{+-}0.021 and w=-0.98{+-}0.07 for the same constant-w model. More general analyses in which we relax the assumption of flatness and/or allow evolution in w remain consistent with the cosmological constant paradigm. Our analysis includes conservative allowances for systematic uncertainties. The small systematic scatter and tight constraints bode well for future dark energy studies using the f{sub gas} method.

  4. Self-similar cosmological solutions with dark energy. II. Black holes, naked singularities, and wormholes

    SciTech Connect (OSTI)

    Maeda, Hideki; Harada, Tomohiro; Carr, B. J.

    2008-01-15

    We use a combination of numerical and analytical methods, exploiting the equations derived in a preceding paper, to classify all spherically symmetric self-similar solutions which are asymptotically Friedmann at large distances and contain a perfect fluid with equation of state p=({gamma}-1){mu} with 0<{gamma}<2/3. The expansion of the Friedmann universe is accelerated in this case. We find a one-parameter family of self-similar solutions representing a black hole embedded in a Friedmann background. This suggests that, in contrast to the positive pressure case, black holes in a universe with dark energy can grow as fast as the Hubble horizon if they are not too large. There are also self-similar solutions which contain a central naked singularity with negative mass and solutions which represent a Friedmann universe connected to either another Friedmann universe or some other cosmological model. The latter are interpreted as self-similar cosmological white hole or wormhole solutions. The throats of these wormholes are defined as two-dimensional spheres with minimal area on a spacelike hypersurface and they are all nontraversable because of the absence of a past null infinity.

  5. 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}.

  6. Eight new Milky Way companions discovered in first-year Dark Energy Survey data

    SciTech Connect (OSTI)

    Bechtol, K.; et al.

    2015-06-30

    We report the discovery of eight new Milky Way companions in $\\sim 1800\\;{\\mathrm{deg}}^{2}$ of optical imaging data collected during the first year of the Dark Energy Survey (DES). Each system is identified as a statistically significant over-density of individual stars consistent with the expected isochrone and luminosity function of an old and metal-poor stellar population. The objects span a wide range of absolute magnitudes (MV from $-2.2$ to $-7.4\\;\\mathrm{mag}$), physical sizes ($10-170\\;\\mathrm{pc}$), and heliocentric distances ($30-330\\;\\mathrm{kpc}$). Based on the low surface brightnesses, large physical sizes, and/or large Galactocentric distances of these objects, several are likely to be new ultra-faint satellite galaxies of the Milky Way and/or Magellanic Clouds. We introduce a likelihood-based algorithm to search for and characterize stellar over-densities, as well as identify stars with high satellite membership probabilities. As a result, we also present completeness estimates for detecting ultra-faint galaxies of varying luminosities, sizes, and heliocentric distances in the first-year DES data.

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

    SciTech Connect (OSTI)

    Li, T.S.; et al.

    2015-09-14

    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 morphologically similar to the Virgo overdensity and the Hercules-Aquila cloud, which also lie at a similar Galactocentric distance. These three overdensities lie along a polar plane separated by ~120 deg and may share a common origin. Spectroscopic follow-up observations of the stars in EriPhe are required to fully understand the nature of this overdensity.

  8. Eight new Milky Way companions discovered in first-year Dark Energy Survey data

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

    Bechtol, K.

    2015-06-30

    We report the discovery of eight new Milky Way companions inmore » $$\\sim 1800\\;{\\mathrm{deg}}^{2}$$ of optical imaging data collected during the first year of the Dark Energy Survey (DES). Each system is identified as a statistically significant over-density of individual stars consistent with the expected isochrone and luminosity function of an old and metal-poor stellar population. The objects span a wide range of absolute magnitudes (MV from $-2.2$ to $$-7.4\\;\\mathrm{mag}$$), physical sizes ($$10-170\\;\\mathrm{pc}$$), and heliocentric distances ($$30-330\\;\\mathrm{kpc}$$). Based on the low surface brightnesses, large physical sizes, and/or large Galactocentric distances of these objects, several are likely to be new ultra-faint satellite galaxies of the Milky Way and/or Magellanic Clouds. We introduce a likelihood-based algorithm to search for and characterize stellar over-densities, as well as identify stars with high satellite membership probabilities. As a result, we also present completeness estimates for detecting ultra-faint galaxies of varying luminosities, sizes, and heliocentric distances in the first-year DES data.« less

  9. Discovery of a stellar overdensity in Eridanus-Phoenix in the dark energy survey

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

    Li, T. S.; Balbinot, E.; Mondrik, N.; Marshall, J. L.; Yanny, B.; Bechtol, K.; Drlica-Wagner, A.; Oscar, D.; Santiago, B.; Simon, J. D.; et al

    2016-01-27

    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 aboutmore » 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 morphologically similar to the Virgo overdensity and the Hercules-Aquila cloud, which also lie at a similar Galactocentric distance. These three overdensities lie along a polar plane separated by ~120 deg and may share a common origin. Spectroscopic follow-up observations of the stars in EriPhe are required to fully understand the nature of this overdensity.« less

  10. Star/galaxy separation at faint magnitudes: Application to a simulated Dark Energy Survey

    SciTech Connect (OSTI)

    Soumagnac, M.T.; et al.

    2013-06-21

    We address the problem of separating stars from galaxies in future large photometric surveys. We focus our analysis on simulations of the Dark Energy Survey (DES). In the first part of the paper, we derive the science requirements on star/galaxy separation, for measurement of the cosmological parameters with the Gravitational Weak Lensing and Large Scale Structure probes. These requirements are dictated by the need to control both the statistical and systematic errors on the cosmological parameters, and by Point Spread Function calibration. We formulate the requirements in terms of the completeness and purity provided by a given star/galaxy classifier. In order to achieve these requirements at faint magnitudes, we propose a new method for star/galaxy separation in the second part of the paper. We first use Principal Component Analysis to outline the correlations between the objects parameters and extract from it the most relevant information. We then use the reduced set of parameters as input to an Artificial Neural Network. This multi-parameter approach improves upon purely morphometric classifiers (such as the classifier implemented in SExtractor), especially at faint magnitudes: it increases the purity by up to 20% for stars and by up to 12% for galaxies, at i-magnitude fainter than 23.