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1

Cosmology with Supernovae  

E-Print Network [OSTI]

This review gives an update of the cosmological use of SNe Ia and the progress made in testing their properties from the local universe to high-z. The cosmological road from high-z supernovae down to Galactic SNe Ia is followed in search of the answer to standing questions on their nature and their validity as cosmological indicators.

P. Ruiz-Lapuente

2003-04-07T23:59:59.000Z

2

Cosmological Insights from Supernovae  

E-Print Network [OSTI]

While low-z Type Ia supernovae are used to measure the present rate of expansion of the Universe, high-z Type Ia measure its variation due to the cosmic matter-energy content. Results from those determinations imply a low matter density Universe with a non-zero cosmological constant (vacuum-energy component). The expansion rate of the Universe accelerates, according to these determinations. The validity of the Type Ia supernova approach for this cosmological research is addressed. An account is given of additional prospects to further investigate through supernovae what the Universe is made of. Those attempts range from constraining the large scale dark matter distribution to further test and interpret the presence of a vacuum energy component.

P. Ruiz-Lapuente

1998-10-26T23:59:59.000Z

3

Cosmological and supernova neutrinos  

SciTech Connect (OSTI)

The Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies are the pillars of modern cosmology. It has recently been suggested that axion which is a dark matter candidate in the framework of the standard model could condensate in the early universe and induce photon cooling before the epoch of the photon last scattering. Although this may render a solution to the overproduction problem of primordial {sup 7}Li abundance, there arises another serious difficulty of overproducing D abundance. We propose a hybrid dark matter model with both axions and relic supersymmetric (SUSY) particles to solve both overproduction problems of the primordial D and {sup 7}Li abundances simultaneously. The BBN also serves to constrain the nature of neutrinos. Considering non-thermal photons produced in the decay of the heavy sterile neutrinos due to the magnetic moment, we explore the cosmological constraint on the strength of neutrino magnetic moment consistent with the observed light element abundances. Core-collapse supernovae eject huge flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. Combining the recent experimental constraints on ?{sub 13} with predicted and observed supernova-produced abundance ratio {sup 11}B/{sup 7}Li encapsulated in the presolar grains from the Murchison meteorite, we show a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos (SRN) that may indicate the softness of the equation of state (EoS) of nuclear matter and adiabatic conditions of the neutrino oscillation.

Kajino, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan Department of Astronomy, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Aoki, W. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Balantekin, A. B. [Department of Physics, University of Wisconsin - Madison, Wisconsin 53706 (United States); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Hayakawa, T. [Japan Atomic Energy Agency, Shirakara-Shirane 2-4, Tokai-mura, Ibaraki 319-1195 (Japan); Hidaka, J. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Hirai, Y.; Shibagaki, S. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Kusakabe, M. [School of Liberal Arts and Science, Korea Aerospace University, Goyang 412-791 (Korea, Republic of); Mathews, G. J. [Department of Physics, University of Notre Dame, IN 46556 (United States); Nakamura, K. [Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Pehlivan, Y. [Mimar Sinan GSÜ, Department of Physics, ?i?li, ?stanbul 34380 (Turkey); Suzuki, T. [Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan)

2014-06-24T23:59:59.000Z

4

Type IIP supernovae as cosmological probes: A SEAM distance to SN 1999em  

E-Print Network [OSTI]

Type IIP Supernovae as Cosmological Probes: A SEAM Distanceintrinsic brightness, supernovae make excellent cosmologicalstars: atmospheres — supernovae: 1999em Distances from

Baron, E.; Nugent, Peter E.; Branch, David; Hauschildt, Peter H.

2004-01-01T23:59:59.000Z

5

The supernova cosmology cookbook: Bayesian numerical recipes  

E-Print Network [OSTI]

Theoretical and observational cosmology have enjoyed a number of significant successes over the last two decades. Cosmic microwave background measurements from the Wilkinson Microwave Anisotropy Probe and Planck, together with large-scale structure and supernova (SN) searches, have put very tight constraints on cosmological parameters. Type Ia supernovae (SNIa) played a central role in the discovery of the accelerated expansion of the Universe, recognised by the Nobel Prize in Physics in 2011. The last decade has seen an enormous increase in the amount of high quality SN observations, with SN catalogues now containing hundreds of objects. This number is expected to increase to thousands in the next few years, as data from next-generation missions, such as the Dark Energy Survey and Large Synoptic Survey Telescope become available. In order to exploit the vast amount of forthcoming high quality data, it is extremely important to develop robust and efficient statistical analysis methods to answer cosmological q...

Karpenka, N V

2015-01-01T23:59:59.000Z

6

Four Papers by the Supernova Cosmology Project  

E-Print Network [OSTI]

K CORRECTIONS FOR TYPE IA SUPERNOVAE AND A TEST FOR SPATIALDILATION USING TYPE IA SUPERNOVAE AS CLOCKS The SupernovaInstitute Thermonuclear Supernovae Conference, Aiguablava,

Perlmutter, S.; Deustua, S.; Gabi, S.; Goldhaber, G.

2008-01-01T23:59:59.000Z

7

Four Papers by the Supernova Cosmology Project  

E-Print Network [OSTI]

Study Institute Thermonuclear Supernovae Conference,STUDY INSTITUTE THERMONUCLEAR SUPERNOVAE Aiguablava, SPAIN20-30, 1995 To appear-in Thermonuclear Supernovae (NATO ASI)

Perlmutter, S.; Deustua, S.; Gabi, S.; Goldhaber, G.

2008-01-01T23:59:59.000Z

8

Towards a Cosmological Hubble Diagram for Type II-P Supernovae  

E-Print Network [OSTI]

Supernova 1987A and other supernovae, ed. I. J. Danziger &I.A.U. Colloquium 192: Supernovae (10 years of SN1993J), ed.A. V. 2005, in 1604-2004: Supernovae as Cosmological Light-

2006-01-01T23:59:59.000Z

9

Ideal bandpasses for type Ia supernova cosmology  

E-Print Network [OSTI]

diversity of type Ia Supernovae, in preparation. Kim, A.error in measurements of supernovae depends on a periodicABSTRACT To use type Ia supernovae as standard candles for

Davis, Tamara M.; Schmidt, Brian P.; Kim, Alex G.

2005-01-01T23:59:59.000Z

10

Probing Cosmological Isotropy With Type IA Supernovae  

E-Print Network [OSTI]

We investigate the validity of the Cosmological Principle by mapping the cosmological parameters $H_0$ and $q_0$ through the celestial sphere. In our analysis, performed in a low-redshift regime to follow a model-independent approach, we use two compilations of type Ia Supernovae (SNe Ia), namely the Union2.1 and the JLA datasets. Firstly, we show that the angular distributions for both SNe Ia datasets are statistically anisotropic at high confidence level ($p$-value $<$ 0.0001), in particular the JLA sample. Then we find that the cosmic expansion and acceleration are mainly of dipolar type, with maximal anisotropic expansion [acceleration] pointing towards $(l,b) \\simeq (326^{\\circ},12^{\\circ})$ [$(l,b) \\simeq (174^{\\circ},27^{\\circ})$], and $(l,b) \\simeq (58^{\\circ},-60^{\\circ})$ [$(l,b) \\simeq (225^{\\circ},51^{\\circ})$] for the Union2.1 and JLA data, respectively. Secondly, we use a geometrical method to test the hypothesis that the non-uniformly distributed SNe Ia events could introduce anisotropic imp...

Bengaly, C A P; Alcaniz, J S

2015-01-01T23:59:59.000Z

11

Improving Type Ia Supernova Standard Candle Cosmology Measurements Using Observations of Early-Type Host Galaxies  

E-Print Network [OSTI]

Host Galaxies of Type Ia Supernovae Introduction SN Ia Hosts109 C HAPTER 1 Cosmology, Type Ia Supernovae and HostGalaxies Observations of supernovae have played a role in

Meyers, Joshua Evan

2012-01-01T23:59:59.000Z

12

Study of Supernovae Important for Cosmology  

E-Print Network [OSTI]

The dense shell method for the determination of distances to type IIn supernovae has been briefly reviewed. Applying our method to SN 2006gy, SN 2009ip, and SN 2010jl supernovae, we have obtained distances in excellent agreement with the previously known distances to the parent galaxies. The dense shell method is based on the radiation hydrodynamic model of a supernova. The method of the blackbody model, as well as the correctness of its application for simple estimates of distances from observation data, has been justified.

Baklanov, P V; Potashov, M Sh; Dolgov, A D

2015-01-01T23:59:59.000Z

13

Cosmological Parameters From Supernovae Associated With Gamma-ray Bursts  

E-Print Network [OSTI]

We report estimates of the cosmological parameters $\\Omega_m$ and $\\Omega_{\\Lambda}$ obtained using supernovae (SNe) associated with gamma-ray bursts (GRBs) at redshifts up to 0.606. Eight high-fidelity GRB-SNe with well-sampled light curves across the peak are used. We correct their peak magnitudes for a luminosity-decline rate relation to turn them into accurate standard candles with dispersion $\\sigma = 0.18$ mag. We also estimate the peculiar velocity of the host galaxy of SN 1998bw, using constrained cosmological simulations. In a flat universe, the resulting Hubble diagram leads to best-fit cosmological parameters of $(\\Omega_m, \\Omega_{\\Lambda}) = (0.52^{+0.34}_{-0.31},0.48^{+0.31}_{-0.34})$. This exploratory study suggests that GRB-SNe can potentially be used as standardizable candles to high redshifts to measure distances in the universe and constrain cosmological parameters.

Li, Xue; Wojtak, Rados?aw

2014-01-01T23:59:59.000Z

14

Scrutinizing Exotic Cosmological Models Using ESSENCE Supernova Data Combined With Other Cosmological Probes  

SciTech Connect (OSTI)

The first cosmological results from the ESSENCE supernova survey (Wood-Vasey et al. 2007) are extended to a wider range of cosmological models including dynamical dark energy and non-standard cosmological models. We fold in a greater number of external data sets such as the recent Higher-z release of high-redshift supernovae (Riess et al. 2007) as well as several complementary cosmological probes. Model comparison statistics such as the Bayesian and Akaike information criteria are applied to gauge the worth of models. These statistics favor models that give a good fit with fewer parameters. Based on this analysis, the preferred cosmological model is the flat cosmological constant model, where the expansion history of the universe can be adequately described with only one free parameter describing the energy content of the universe. Amongst the more exotic models that provide good fits to the data, we note a preference for models whose best-fit parameters reduce them to the cosmological constant model.

Davis, Tamara M.; Mortsell, E.; Sollerman, J.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Filippenko, A.V.; Foley, R.J.; Garnavich, P.M.; Jha, S.; Krisciunas, K.; Kirshner, R.P.; Leibundgut, B.; Li, W.; Matheson, T.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; Schmidt, B.P.; /Bohr Inst. /Stockholm U. /Washington U.,

2007-01-25T23:59:59.000Z

15

Testing Cosmological Models with Type Ic Super Luminous Supernovae  

E-Print Network [OSTI]

The use of type Ic Super Luminous Supernovae (SLSN Ic) to examine the cosmological expansion introduces a new standard ruler with which to test theoretical models. The sample suitable for this kind of work now includes 11 SLSNe Ic, which have thus far been used solely in tests involving $\\Lambda$CDM. In this paper, we broaden the base of support for this new, important cosmic probe by using these observations to carry out a one-on-one comparison between the $R_{\\rm h}=ct$ and $\\Lambda$CDM cosmologies. We individually optimize the parameters in each cosmological model by minimizing the $\\chi^{2}$ statistic. We also carry out Monte Carlo simulations based on these current SLSN Ic measurements to estimate how large the sample would have to be in order to rule out either model at a $\\sim 99.7\\%$ confidence level. The currently available sample indicates a likelihood of $\\sim$$70-80\\%$ that the $R_{\\rm h}=ct$ Universe is the correct cosmology versus $\\sim$$20-30\\%$ for the standard model. These results are suggest...

Wei, Jun-Jie; Melia, Fulvio

2015-01-01T23:59:59.000Z

16

COSMOLOGY WITH PHOTOMETRICALLY CLASSIFIED TYPE Ia SUPERNOVAE FROM THE SDSS-II SUPERNOVA SURVEY  

SciTech Connect (OSTI)

We present the cosmological analysis of 752 photometrically classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey. Our photometric-classification method is based on the SN classification technique of Sako et al., aided by host-galaxy redshifts (0.05 < z < 0.55). SuperNova ANAlysis simulations of our methodology estimate that we have an SN Ia classification efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia) SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints. We quantify and correct for our selection effects (e.g., Malmquist bias) using simulations. When fitting to a flat {Lambda}CDM cosmological model, we find that our photometric sample alone gives {Omega} {sub m} = 0.24{sup +0.07} {sub -0.05} (statistical errors only). If we relax the constraint on flatness, then our sample provides competitive joint statistical constraints on {Omega} {sub m} and {Omega}{sub {Lambda}}, comparable to those derived from the spectroscopically confirmed Three-year Supernova Legacy Survey (SNLS3). Using only our data, the statistics-only result favors an accelerating universe at 99.96% confidence. Assuming a constant wCDM cosmological model, and combining with H {sub 0}, cosmic microwave background, and luminous red galaxy data, we obtain w = -0.96{sup +0.10} {sub -0.10}, {Omega} {sub m} = 0.29{sup +0.02} {sub -0.02}, and {Omega} {sub k} = 0.00{sup +0.03} {sub -0.02} (statistical errors only), which is competitive with similar spectroscopically confirmed SNe Ia analyses. Overall this comparison is reassuring, considering the lower redshift leverage of the SDSS-II SN sample (z < 0.55) and the lack of spectroscopic confirmation used herein. These results demonstrate the potential of photometrically classified SN Ia samples in improving cosmological constraints.

Campbell, Heather; D'Andrea, Chris B; Nichol, Robert C.; Smith, Mathew; Lampeitl, Hubert [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)] [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Sako, Masao [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States)] [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Olmstead, Matthew D.; Brown, Peter; Dawson, Kyle S. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East 201, Salt Lake City, UT 84112 (United States)] [Department of Physics and Astronomy, University of Utah, 115 South 1400 East 201, Salt Lake City, UT 84112 (United States); Bassett, Bruce [Mathematics Department, University of Cape Town, Rondebosch, Cape Town (South Africa)] [Mathematics Department, University of Cape Town, Rondebosch, Cape Town (South Africa); Biswas, Rahul; Kuhlmann, Steve [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)] [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States); Cinabro, David [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48126 (United States)] [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48126 (United States); Dilday, Ben [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States)] [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Frieman, Joshua A. [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)] [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Hlozek, Renee [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)] [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Jha, Saurabh W. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)] [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Kunz, Martin, E-mail: Heather.Campbell@port.ac.uk [African Institute for Mathematical Sciences, Muizenberg, 7945, Cape Town (South Africa)] [African Institute for Mathematical Sciences, Muizenberg, 7945, Cape Town (South Africa); and others

2013-02-15T23:59:59.000Z

17

LIGHTCURVES OF THERMONUCLEAR SUPERNOVAE AS A PROBE OF THE EXPLOSION MECHANISM AND THEIR USE IN COSMOLOGY  

E-Print Network [OSTI]

Thermonuclear supernovae are valuable for cosmology but their physics is not yet fully understood. Modeling the development and propagation of nuclear flame is complicated by numerous instabilities. The predictions of supernova light curves still involve some simplifying assumptions, but one can use the comparison of the computed fluxes with observations to constrain the explosion mechanism. In spite of great progress in recent years, a number of issues remains unsolved both in flame physics and light curve modeling. 1

S. I. Blinnikov; E. I. Sorokina

2002-01-01T23:59:59.000Z

18

Lightcurves of thermonuclear supernovae as a probe of the explosion mechanism and their use in cosmology  

E-Print Network [OSTI]

Thermonuclear supernovae are valuable for cosmology but their physics is not yet fully understood. Modeling the development and propagation of nuclear flame is complicated by numerous instabilities. The predictions of supernova light curves still involve some simplifying assumptions, but one can use the comparison of the computed fluxes with observations to constrain the explosion mechanism. In spite of great progress in recent years, a number of issues remains unsolved both in flame physics and light curve modeling.

S. Blinnikov; E. Sorokina

2002-12-30T23:59:59.000Z

19

Cosmological Constant Problems and Renormalization Group  

E-Print Network [OSTI]

The Cosmological Constant Problem emerges when Quantum Field Theory is applied to the gravitational theory, due to the enormous magnitude of the induced energy of the vacuum. The unique known solution of this problem involves an extremely precise fine-tuning of the vacuum counterpart. We review a few of the existing approaches to this problem based on the account of the quantum (loop) effects and pay special attention to the ones involving the renormalization group.

Ilya L. Shapiro; Joan Sola

2007-01-05T23:59:59.000Z

20

Type Ia Supernova Intrinsic Magnitude Dispersion and the Fitting of Cosmological Parameters  

SciTech Connect (OSTI)

I present an analysis for fitting cosmological parameters from a Hubble Diagram of a standard candle with unknown intrinsic magnitude dispersion. The dispersion is determined from the data themselves, simultaneously with the cosmological parameters. This contrasts with the strategies used to date. The advantages of the presented analysis are that it is done in a single fit (it is not iterative), it provides a statistically founded and unbiased estimate of the intrinsic dispersion, and its cosmological-parameter uncertainties account for the intrinsic dispersion uncertainty. Applied to Type Ia supernovae, my strategy provides a statistical measure to test for sub-types and assess the significance of any magnitude corrections applied to the calibrated candle. Parameter bias and differences between likelihood distributions produced by the presented and currently-used fitters are negligibly small for existing and projected supernova data sets.

Kim, Alex G

2010-12-10T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Optimal Extraction of Cosmological Information from Supernova Datain the Presence of Calibration Uncertainties  

SciTech Connect (OSTI)

We present a new technique to extract the cosmological information from high-redshift supernova data in the presence of calibration errors and extinction due to dust. While in the traditional technique the distance modulus of each supernova is determined separately, in our approach we determine all distance moduli at once, in a process that achieves a significant degree of self-calibration. The result is a much reduced sensitivity of the cosmological parameters to the calibration uncertainties. As an example, for a strawman mission similar to that outlined in the SNAP satellite proposal, the increased precision obtained with the new approach is roughly equivalent to a factor of five decrease in the calibration uncertainty.

Kim, Alex G.; Miquel, Ramon

2005-09-26T23:59:59.000Z

22

Type Ia Supernova Intrinsic Magnitude Dispersion and the Fitting of Cosmological Parameters  

E-Print Network [OSTI]

Applied to Type Ia supernovae, my strategy provides adata sets. Subject headings: Supernovae: Data Analysis andhomogeneous nature of Type Ia supernovae (SNe Ia) makes them

Kim, Alex G

2011-01-01T23:59:59.000Z

23

Verifying the Cosmological Utility of Type Ia Supernovae: Implications of a Dispersion in the Ultraviolet Spectra  

E-Print Network [OSTI]

Utility of Type Ia Supernovae: Implications of a Dispersionheadings: surveys – supernovae: general – cosmologicalparameters Introduction Supernovae of Type Ia (SNe Ia) are

2008-01-01T23:59:59.000Z

24

Discovery of a Supernova Explosion at Half the Age of the Universe and its Cosmological Implications  

E-Print Network [OSTI]

and Bounds on qo. in Thermonuclear Supernovae (eds P. Ruiz-novae as clocks. in Thermonuclear Supernovae (eds P. Ruiz-distance indicators. in Thermonuclear Supernovae (eds P.

Perlmutter, S.

2010-01-01T23:59:59.000Z

25

Constructing a cosmological model-independent Hubble diagram of type Ia supernovae with cosmic chronometers  

E-Print Network [OSTI]

We apply two methods to reconstruct the Hubble parameter $H(z)$ as a function of redshift from 15 measurements of the expansion rate obtained from age estimates of passively evolving galaxies. These reconstructions enable us to derive the luminosity distance to a certain redshift $z$, calibrate the light-curve fitting parameters accounting for the (unknown) intrinsic magnitude of type Ia supernova (SNe Ia) and construct cosmological model-independent Hubble diagrams of SNe Ia. In order to test the compatibility between the reconstructed functions of $H(z)$, we perform a statistical analysis considering the latest SNe Ia sample, the so-called JLA compilation. We find that, while one of the reconstructed functions leads to a value of the local Hubble parameter $H_0$ in excellent agreement with the one reported by the Planck collaboration, the other requires a higher value of $H_0$, which is consistent with recent measurements of this quantity from Cepheids and other local distance indicators.

Li, Zhengxiang; Yu, Hongwei; Zhu, Zong-Hong; Alcaniz, J S

2015-01-01T23:59:59.000Z

26

Verifying the Cosmological Utility of Type Ia Supernovae: Implications of a Dispersion in the Ultraviolet Spectra  

SciTech Connect (OSTI)

We analyze the mean rest-frame ultraviolet (UV) spectrum of Type Ia Supernovae (SNe) and its dispersion using high signal-to-noise ratio Keck-I/LRIS-B spectroscopy for a sample of 36 events at intermediate redshift (z=0.5) discovered by the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We introduce a new method for removing host galaxy contamination in our spectra, exploiting the comprehensive photometric coverage of the SNLS SNe and their host galaxies, thereby providing the first quantitative view of the UV spectral properties of a large sample of distant SNe Ia. Although the mean SN Ia spectrum has not evolved significantly over the past 40percent of cosmic history, precise evolutionary constraints are limited by the absence of a comparable sample of high-quality local spectra. The mean UV spectrum of our z~;;=0.5 SNe Ia and its dispersion is tabulated for use in future applications. Within the high-redshift sample, we discover significant UV spectral variations and exclude dust extinction as the primary cause by examining trends with the optical SN color. Although progenitor metallicity may drive some of these trends, the variations we see are much larger than predicted in recent models and do not follow expected patterns. An interesting new result is a variation seen in the wavelength of selected UV features with phase. We also demonstrate systematic differences in the SN Ia spectral features with SN light curve width in both the UV and the optical. We show that these intrinsic variations could represent a statistical limitation in the future use of high-redshift SNe Ia for precision cosmology. We conclude that further detailed studies are needed, both locally and at moderate redshift where the rest-frame UV can be studied precisely, in order that future missions can confidently be planned to fully exploit SNe Ia as cosmological probes.

Nugent, Peter E; Ellis, R.S.; Sullivan, M.; Nugent, P.E.; Howell, D.A.; Gal-Yam, A.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R.; Conley, A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I.; Pain, R.; Perrett, K.; Pritchet, C.J.; Regnault, N.

2008-02-28T23:59:59.000Z

27

Feasibility of Measuring the Cosmological Constant [LAMBDA] and Mass Density [Omega] using Type Ia Supernovae  

E-Print Network [OSTI]

at z = 1. uncertainty for supernovae at z = 1. mR Adding theMass Density .Q Using Type Ia Supernovae A. Goobar and S.Density Q Using Type Ia Supernovae Ariel Goobar l and Saul

Goobar, A.

2008-01-01T23:59:59.000Z

28

Discovery of a Supernova Explosion at Half the Age of the Universe and its Cosmological Implications  

E-Print Network [OSTI]

ULDA Access Guide No.6: Supernovae (eds Cappellaro, E. ,of light curves of supernovae type 1. Astra. Astrophys.magnitudes of Type la supernovae. Astrophys. J. 413, LI05-

Perlmutter, S.

2010-01-01T23:59:59.000Z

29

Optimal Extraction of Cosmological Information from Supernova Data in the Presence of Calibration Uncertainties  

E-Print Network [OSTI]

The study of type-la supernovae provided the firstResults from more recent supernovae surveys [5, 6] further8] techniques to turn type-la supernovae into standardized

Kim, Alex G.; Miquel, Ramon

2005-01-01T23:59:59.000Z

30

Observational Constraints on the Nature of the Dark Energy: First Cosmological Results From the ESSENCE Supernova Survey  

SciTech Connect (OSTI)

We present constraints on the dark energy equation-of-state parameter, w = P/({rho}c{sup 2}), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat Universe. By including constraints on ({Omega}{sub M}, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1.05{sub -0.12}{sup +0.13} (stat 1{sigma}) {+-} 0.13 (sys) and {Omega}{sub M} = 0.274{sub -0.020}{sup +0.033} (stat 1{sigma}) with a best-fit {chi}{sup 2}/DoF of 0.96. These results are consistent with those reported by the Super-Nova Legacy Survey in a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic currently with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the SuperNova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1.07{sub -0.09}{sup +0.09} (stat 1{sigma}) {+-} 0.13 (sys), {Omega}{sub M} = 0.267{sub -0.018}{sup +0.028} (stat 1{sigma}) with a best-fit {chi}{sup 2}/DoF of 0.91. The current SNe Ia data are fully consistent with a cosmological constant.

Wood-Vasey, W.Michael; Miknaitis, G.; Stubbs, C.W.; Jha, S.; Riess, A.G.; Garnavich, P.M.; Kirshner, R.P.; Aguilera, C.; Becker, A.C.; Blackman, J.W.; Blondin, S.; Challis, P.; Clocchiatti, A.; Conley, A.; Covarrubias, R.; Davis, T.M.; Filippenko, A.V.; Foley, R.J.; Garg, A.; Hicken, M.; Krisciunas, K.; /Harvard-Smithsonian Ctr. Astrophys.

2007-01-05T23:59:59.000Z

31

Cosmological-model-parameter determination from satellite-acquired type Ia and IIP Supernova Data  

E-Print Network [OSTI]

Since the B i g B a n g : Supernovae a n d G a m m a - R a ythe universe—space vehicles—supernovae: general Introductionbased on T y p e l a supernovae (hereafter S N e la) have

Podariu, Silviu; Nugent, Peter; Ratra, Bharat

2000-01-01T23:59:59.000Z

32

Higgs boson, renormalization group, and naturalness in cosmology  

E-Print Network [OSTI]

We consider the renormalization group improvement in the theory of the Standard Model (SM) Higgs boson playing the role of an inflaton with a strong non-minimal coupling to gravity. At the one-loop level with the running of constants taken into account, it leads to a range of the Higgs mass that is entirely determined by the lower WMAP bound on the cosmic microwave background (CMB) spectral index. We find that the SM phenomenology is sensitive to current cosmological data, which suggests to perform more precise CMB measurements as a SM test complementary to the LHC program. By using the concept of a field-dependent cutoff, we show the naturalness of the gradient and curvature expansion in this model within the conventional perturbation theory range of the SM. We also discuss the relation of these results to two-loop calculations and the limitations of the latter caused by parametrization and gauge dependence problems.

A. O. Barvinsky; A. Yu. Kamenshchik; C. Kiefer; A. A. Starobinsky; C. F. Steinwachs

2012-11-05T23:59:59.000Z

33

Verifying the Cosmological Utility of Type Ia Supernovae:Implications of a Dispersion in the Ultraviolet Spectra  

SciTech Connect (OSTI)

We analyze the mean rest-frame ultraviolet (UV) spectrum ofType Ia Supernovae(SNe) and its dispersion using high signal-to-noiseKeck-I/LRIS-B spectroscopyfor a sample of 36 events at intermediateredshift (z=0.5) discoveredby the Canada-France-Hawaii TelescopeSupernova Legacy Survey (SNLS). Weintroduce a new method for removinghost galaxy contamination in our spectra,exploiting the comprehensivephotometric coverage of the SNLS SNe and theirhost galaxies, therebyproviding the first quantitative view of the UV spectralproperties of alarge sample of distant SNe Ia. Although the mean SN Ia spectrumhas notevolved significantly over the past 40 percent of cosmic history,preciseevolutionary constraints are limited by the absence of acomparable sample ofhigh quality local spectra. The mean UV spectrum ofour z 0.5 SNe Ia and itsdispersion is tabulated for use in futureapplications. Within the high-redshiftsample, we discover significant UVspectral variations and exclude dust extinctionas the primary cause byexamining trends with the optical SN color. Although progenitormetallicity may drive some of these trends, the variations we see aremuchlarger than predicted in recent models and do not follow expectedpatterns.An interesting new result is a variation seen in the wavelengthof selected UVfeatures with phase. We also demonstrate systematicdifferences in the SN Iaspectral features with SN lightcurve width inboth the UV and the optical. Weshow that these intrinsic variations couldrepresent a statistical limitation in thefuture use of high-redshift SNeIa for precision cosmology. We conclude thatfurther detailed studies areneeded, both locally and at moderate redshift wherethe rest-frame UV canbe studied precisely, in order that future missions canconfidently beplanned to fully exploit SNe Ia as cosmological probes.

Ellis, R.S.; Sullivan, M.; Nugent, P.E.; Howell, D.A.; Gal-Yam,A.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R.G.; Conley,A.; Fouchez, D.; Guy, J.; Hardin, D.; Hook, I.; Pain, R.; Perrett, K.; Pritchet, C.J.; Regnault, N.

2007-11-02T23:59:59.000Z

34

TESTING MODELS OF INTRINSIC BRIGHTNESS VARIATIONS IN TYPE Ia SUPERNOVAE AND THEIR IMPACT ON MEASURING COSMOLOGICAL PARAMETERS  

SciTech Connect (OSTI)

For spectroscopically confirmed Type Ia supernovae we evaluate models of intrinsic brightness variations with detailed data/Monte Carlo comparisons of the dispersion in the following quantities: Hubble-diagram scatter, color difference (B - V - c) between the true B - V color and the fitted color (c) from the SALT-II light curve model, and photometric redshift residual. The data sample includes 251 ugriz light curves from the three-season Sloan Digital Sky Survey-II and 191 griz light curves from the Supernova Legacy Survey 3 year data release. We find that the simplest model of a wavelength-independent (coherent) scatter is not adequate, and that to describe the data the intrinsic-scatter model must have wavelength-dependent variations resulting in a {approx}0.02 mag scatter in B - V - c. Relatively weak constraints are obtained on the nature of intrinsic scatter because a variety of different models can reasonably describe this photometric data sample. We use Monte Carlo simulations to examine the standard approach of adding a coherent-scatter term in quadrature to the distance-modulus uncertainty in order to bring the reduced {chi}{sup 2} to unity when fitting a Hubble diagram. If the light curve fits include model uncertainties with the correct wavelength dependence of the scatter, we find that this approach is valid and that the bias on the dark energy equation-of-state parameter w is much smaller ({approx}0.001) than current systematic uncertainties. However, incorrect model uncertainties can lead to a significant bias on the distance moduli, with up to {approx}0.05 mag redshift-dependent variation. This bias is roughly reduced in half after applying a Malmquist bias correction. For the recent SNLS3 cosmology results, we estimate that this effect introduces an additional systematic uncertainty on w of {approx}0.02, well below the total uncertainty. This uncertainty depends on the choice of viable scatter models and the choice of supernova (SN) samples, and thus this small w-uncertainty is not guaranteed in future cosmology results. For example, the w-uncertainty for SDSS+SNLS (dropping the nearby SNe) increases to {approx}0.04.

Kessler, Richard; Frieman, Joshua A. [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)] [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Guy, Julien; Betoule, Marc; El-Hage, Patrick [Laboratoire de Physique Nucleaire et des Hautes Energies, UPMC Univ. Paris 6, UPD Univ. Paris 7, CNRS IN2P3, 4 place Jussieu, F-75005 Paris (France)] [Laboratoire de Physique Nucleaire et des Hautes Energies, UPMC Univ. Paris 6, UPD Univ. Paris 7, CNRS IN2P3, 4 place Jussieu, F-75005 Paris (France); Marriner, John [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States)] [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Brinkmann, Jon [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States)] [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Cinabro, David [Department of Physics, Wayne State University, Detroit, MI 48202 (United States)] [Department of Physics, Wayne State University, Detroit, MI 48202 (United States); Jha, Saurabh [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)] [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Mosher, Jennifer [Department of Physics and Astronomy, University of Pennsylvania, 203 South 33rd Street, Philadelphia, PA 19104 (United States)] [Department of Physics and Astronomy, University of Pennsylvania, 203 South 33rd Street, Philadelphia, PA 19104 (United States); Schneider, Donald P., E-mail: kessler@kicp.uchicago.edu [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

2013-02-10T23:59:59.000Z

35

Timescale stretch parameterization of Type Ia supernova B-band light curves  

E-Print Network [OSTI]

the light curve of Type Ia supernovae discovered by theof the high-redshift supernovae. This work was supported inobjects. Subject headings: supernovae: general – cosmology:

2001-01-01T23:59:59.000Z

36

Snapping Supernovae at z>1.7  

E-Print Network [OSTI]

LBNL-61879 Snapping Supernovae at z > 1.7 Greg Aldering,of California. Snapping Supernovae at z > 1.7 Greg Aldering,of very high redshift Type Ia supernovae for cosmology and

Aldering, Greg

2009-01-01T23:59:59.000Z

37

Aspherical supernovae  

SciTech Connect (OSTI)

Although we know that many supernovae are aspherical, the exact nature of their geometry is undetermined. Because all the supernovae we observe are too distant to be resolved, the ejecta structure can't be directly imaged, and asymmetry must be inferred from signatures in the spectral features and polarization of the supernova light. The empirical interpretation of this data, however, is rather limited--to learn more about the detailed supernova geometry, theoretical modeling must been undertaken. One expects the geometry to be closely tied to the explosion mechanism and the progenitor star system, both of which are still under debate. Studying the 3-dimensional structure of supernovae should therefore provide new break throughs in our understanding. The goal of this thesis is to advance new techniques for calculating radiative transfer in 3-dimensional expanding atmospheres, and use them to study the flux and polarization signatures of aspherical supernovae. We develop a 3-D Monte Carlo transfer code and use it to directly fit recent spectropolarimetric observations, as well as calculate the observable properties of detailed multi-dimensional hydrodynamical explosion simulations. While previous theoretical efforts have been restricted to ellipsoidal models, we study several more complicated configurations that are tied to specific physical scenarios. We explore clumpy and toroidal geometries in fitting the spectropolarimetry of the Type Ia supernova SN 2001el. We then calculate the observable consequences of a supernova that has been rendered asymmetric by crashing into a nearby companion star. Finally, we fit the spectrum of a peculiar and extraordinarily luminous Type Ic supernova. The results are brought to bear on three broader astrophysical questions: (1) What are the progenitors and the explosion processes of Type Ia supernovae? (2) What effect does asymmetry have on the observational diversity of Type Ia supernovae, and hence their use in cosmology? (3) And , what are some of the physical properties of Type Ic supernovae, believed to be associated with gamma-ray bursts?

Kasen, Daniel Nathan

2004-05-21T23:59:59.000Z

38

The kinematics of the Local Group in a cosmological context  

E-Print Network [OSTI]

Recent observations constrained the tangential velocity of M31 with respect to the Milky Way (MW) to be v_tan<34.4 km/s and the radial velocity to be in the range v_rad=-109+/- 4.4 km/s (van der Marel et al. 2012). In this study we use a large volume high resolution N-body cosmological simulation (Bolshoi) together with three constrained simulations to statistically study this kinematics in the context of the LCDM. The comparison of the ensembles of simulated pairs with the observed LG at the 1-sigma level in the uncertainties has been done with respect to the radial and tangential velocities, the reduced orbital energy (e_tot), angular momentum (l_orb) and the dimensionless spin parameter, lambda. Our main results are: (i) the preferred radial and tangential velocities for pairs in LCDM are v_rad=-80+/-20 km/s, v_tan=50+/-10 km/s, (ii) pairs around that region are 3 to 13 times more common than pairs within the observational values, (iii) 15%to 24% of LG-like pairs in LCDM have energy and angular momentum...

Forero-Romero, Jaime E; Bustamante, Sebastian; Gottloeber, Stefan; Yepes, Gustavo

2013-01-01T23:59:59.000Z

39

The farthest known supernova: Support for an accelerating universe and a glimpse of the epoch of deceleration  

E-Print Network [OSTI]

ULDA Access Guide No. 6: Supernovae (The Netherlands: ESA)Livio, M. 2000, in Type Ia Supernovae: Theory and Cosmology,T. 2000, in Type Ia Supernovae: Theory and Cosmology, eds.

2001-01-01T23:59:59.000Z

40

Testing Models of Intrinsic Brightness Variations in Type Ia Supernovae, and their Impact on Measuring Cosmological Parameters  

E-Print Network [OSTI]

For spectroscopically confirmed type Ia supernovae we evaluate models of intrinsic brightness variations with detailed data/Monte-Carlo comparisons of the dispersion in the following quantities: Hubble-diagram scatter, color difference (B-V-c) between the true B-V color and the fitted color (c) from the SALT-II light curve model, and photometric redshift residual. The data sample includes 251 ugriz light curves from the 3-season Sloan Digital Sky Survey-II, and 191 griz light curves from the Supernova Legacy Survey 3-year data release. We find that the simplest model of a wavelength independent (coherent) scatter is not adequate, and that to describe the data the intrinsic scatter model must have wavelength-dependent variations. We use Monte Carlo simulations to examine the standard approach of adding a coherent scatter term in quadrature to the distance-modulus uncertainty in order to bring the reduced chi2 to unity when fitting a Hubble diagram. If the light curve fits include model uncertainties with the c...

Kessler, Richard; Marriner, John; Betoule, Marc; Brinkmann, Jon; Cinabro, David; El-Hage, Patrick; Frieman, Joshua; Jha, Saurabh; Mosher, Jennifer; Schneider, Donald P

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Thermonuclear Supernovae  

E-Print Network [OSTI]

The application of Type Ia supernovae (SNe Ia) as distance indicators in cosmology calls for a sound understanding of these objects. Recent years have seen a brisk development of astrophysical models which explain SNe Ia as thermonuclear explosions of white dwarf stars. While the evolution of the progenitor is still uncertain, the explosion mechanism certainly involves the propagation of a thermonuclear flame through the white dwarf star. Three-dimensional hydrodynamical simulations allowed to study a wide variety of possibilities involving subsonic flame propagation (deflagrations), flames accelerated by turbulence, and supersonic detonations. These possibilities lead to a variety of scenarios. I review the currently discussed approaches and present some recent results from simulations of the turbulent deflagration model and the delayed detonation model.

F. K. Roepke

2008-04-14T23:59:59.000Z

42

Aspherical supernovae  

E-Print Network [OSTI]

g h t : T h e Physics of Supernovae, ed. W . H i l l e b r ar a n c h , D . 1990, i n Supernovae, Jerusalem W i n t e ri o , M . 2000, i n T y p e Ia Supernovae, T h e o r y a n d

Kasen, Daniel Nathan

2004-01-01T23:59:59.000Z

43

Cosmological constraints from the virial mass function of nearby galaxy groups and clusters  

E-Print Network [OSTI]

In this thesis, I present a new determination of the cluster mass function in a volume ~107 h-03 70 Mpc3 using the ROSAT-2MASS-FAST Group Survey (R2FGS). R2FGS is an X-ray-selected sample of systems from the ROSAT All-Sky ...

Hill, James Colin

2008-01-01T23:59:59.000Z

44

Supernova bangs as a tool to study big bang  

SciTech Connect (OSTI)

Supernovae and gamma-ray bursts are the most powerful explosions in observed Universe. This educational review tells about supernovae and their applications in cosmology. It is explained how to understand the production of light in the most luminous events with minimum required energy of explosion. These most luminous phenomena can serve as primary cosmological distance indicators. Comparing the observed distance dependence on red shift with theoretical models one can extract information on evolution of the Universe from Big Bang until our epoch.

Blinnikov, S. I., E-mail: Sergei.Blinnikov@itep.ru [Institute for Theoretical and Experimental Physics (Russian Federation)

2012-09-15T23:59:59.000Z

45

The nearby supernova factory  

E-Print Network [OSTI]

cadence gives fewer supernovae but better constraints on thein 2003. Key words: supernovae, galaxies Preprint submitted2004 Introduction Type Ia supernovae (SNe Ia) have proven

2004-01-01T23:59:59.000Z

46

The ESSENCE Supernova Survey: Survey Optimization, Observations, and Supernova Photometry  

SciTech Connect (OSTI)

We describe the implementation and optimization of the ESSENCE supernova survey, which we have undertaken to measure the equation of state parameter of the dark energy. We present a method for optimizing the survey exposure times and cadence to maximize our sensitivity to the dark energy equation of state parameter w = P/{rho}c{sup 2} for a given fixed amount of telescope time. For our survey on the CTIO 4m telescope, measuring the luminosity distances and redshifts for supernovae at modest redshifts (z {approx} 0.5 {+-} 0.2) is optimal for determining w. We describe the data analysis pipeline based on using reliable and robust image subtraction to find supernovae automatically and in near real-time. Since making cosmological inferences with supernovae relies crucially on accurate measurement of their brightnesses, we describe our efforts to establish a thorough calibration of the CTIO 4m natural photometric system. In its first four years, ESSENCE has discovered and spectroscopically confirmed 102 type Ia SNe, at redshifts from 0.10 to 0.78, identified through an impartial, effective methodology for spectroscopic classification and redshift determination. We present the resulting light curves for the all type Ia supernovae found by ESSENCE and used in our measurement of w, presented in Wood-Vasey et al. (2007).

Miknaitis, Gajus; Pignata, G.; Rest, A.; Wood-Vasey, W.M.; Blondin, S.; Challis, P.; Smith, R.C.; Stubbs, C.W.; Suntzeff, N.B.; Foley, R.J.; Matheson, T.; Tonry, J.L.; Aguilera, C.; Blackman, J.W.; Becker, A.C.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Filippenko, A.V.; Garg, A.; Garnavich, P.M.; /Fermilab /Chile U., Catolica /Cerro-Tololo

2007-01-08T23:59:59.000Z

47

Supernovae. Part II: The aftermath  

E-Print Network [OSTI]

R. Viswanathan, 1980, As- Supernovae. Part II ExperimentalSmith, 1982, Astrophys. Supernovae. Chevalier, R. A. , andC. B. , 1974, Ed. , Supernovae and Supernova Rem- nants,

Trimble, V

1983-01-01T23:59:59.000Z

48

THE TIP OF THE RED GIANT BRANCH DISTANCES TO TYPE Ia SUPERNOVA HOST GALAXIES. II. M66 AND M96 IN THE LEO I GROUP  

SciTech Connect (OSTI)

M66 and M96 in the Leo I Group are nearby spiral galaxies hosting Type Ia supernovae (SNe Ia). We estimate the distances to these galaxies from the luminosity of the tip of the red giant branch (TRGB). We obtain VI photometry of resolved stars in these galaxies from F555W and F814W images in the Hubble Space Telescope archive. From the luminosity function of these red giants, we find the TRGB I-band magnitude to be I{sub TRGB} = 26.20 {+-} 0.03 for M66 and 26.21 {+-} 0.03 for M96. These values yield distance modulus (m - M){sub 0} = 30.12 {+-} 0.03(random) {+-} 0.12(systematic) for M66 and (m - M){sub 0} = 30.15 {+-} 0.03(random) {+-} 0.12(systematic) for M96. These results show that they are indeed the members of the same group. With these results we derive absolute maximum magnitudes of two SNe (SN 1989B in M66 and SN 1998bu in M96). V-band magnitudes of these SNe Ia are {approx}0.2 mag fainter than SN 2011fe in M101, one of the nearest recent SNe Ia. We also derive near-infrared magnitudes for SN 1998bu. Optical magnitudes of three SNe Ia (SN 1989B, SN 1998bu, and SN 2011fe) based on TRGB analysis yield a Hubble constant, H{sub 0} = 68.4 {+-} 2.6(random) {+-} 3.7(systematic) km s{sup -1} Mpc{sup -1}. This value is similar to the values derived from recent WMAP9 results, H{sub 0} = 69.32 {+-} 0.80 km s{sup -1} Mpc{sup -1}, and from Planck results, H{sub 0} = 67.3 {+-} 1.2 km s{sup -1} Mpc{sup -1}, but smaller than other recent determinations based on Cepheid calibration for SNe Ia luminosity, H{sub 0} = 74 {+-} 3 km s{sup -1} Mpc{sup -1}.

Lee, Myung Gyoon; Jang, In Sung, E-mail: mglee@astro.snu.ac.kr, E-mail: isjang@astro.snu.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

2013-08-10T23:59:59.000Z

49

Dust around Type Ia supernovae  

E-Print Network [OSTI]

Dust around Type Ia supernovae Lifan Wang 1,2 LawrenceIa. Subject headings: Supernovae: General, Dust, Extinctionline) bands for Type Ia supernovae. (a), upper panel, shows

Wang, Lifan

2005-01-01T23:59:59.000Z

50

K-corrections and extinction corrections for Type Ia supernovae  

SciTech Connect (OSTI)

The measurement of the cosmological parameters from Type Ia supernovae hinges on our ability to compare nearby and distant supernovae accurately. Here we present an advance on a method for performing generalized K-corrections for Type Ia supernovae which allows us to compare these objects from the UV to near-IR over the redshift range 0 < z < 2. We discuss the errors currently associated with this method and how future data can improve upon it significantly. We also examine the effects of reddening on the K-corrections and the light curves of Type Ia supernovae. Finally, we provide a few examples of how these techniques affect our current understanding of a sample of both nearby and distant supernovae.

Nugent, Peter; Kim, Alex; Perlmutter, Saul

2002-05-21T23:59:59.000Z

51

Supernovae and the IGM  

E-Print Network [OSTI]

An energetic argument implies that a galaxy like the Milky Way is blowing a powerful wind that carries away most of the heavy elements currently synthesized and has impacted the IGM out to at least 180 kpc. Rich clusters of galaxies appear to be closed systems in which most heavy elements are ejected from galaxies. More supernovae are required than the yield of core-collapse SNe from a Salpeter IMF. X-ray observations imply that the IGM in groups and clusters as been strongly preheated. SNe probably cannot supply the required energy, which must come from AGN.

James Binney

2000-08-23T23:59:59.000Z

52

Thermonuclear Burning Regimes and the Use of SNe Ia in Cosmology  

E-Print Network [OSTI]

The calculations of the light curves of thermonuclear supernovae are carried out by a method of multi-group radiation hydrodynamics. The effects of spectral lines and expansion opacity are taken into account. The predictions for UBVI fluxes are given. The values of rise time for B and V bands found in our calculations are in good agreement with the observed values. We explain why our results for the rise time have more solid physical justification than those obtained by other authors. It is shown that small variations in the chemical composition of the ejecta, produced in the explosions with different regimes of nuclear burning, can influence drastically the light curve decline in the B band and, to a lesser extent, in the V band. We argue that recent results on positive cosmological constant Lambda, found from the high redshift supernova observations, could be wrong in the case of possible variations of the preferred mode of nuclear burning in the earlier Universe.

E. I. Sorokina; S. I. Blinnikov; O. S. Bartunov

1999-10-02T23:59:59.000Z

53

Supernova Spectra  

E-Print Network [OSTI]

In this paper are summarized the main advances of the last years in the field of SN spectra . The arguments against a monodimensional sequence for SNIa are discussed as well as the efforts to improve the temporal and spectral coverage of this kind of SNe, with the aim to understand the physics of the explosions for their use as cosmological distance indicators. Although variety is the main character of core-collapse SNe, we have been recently surprised by both exceptionally under- and over-energetic explosions. The main properties of these two extreme subclasses are here reviewed.

M. Turatto

2003-10-29T23:59:59.000Z

54

Relics of subluminous supernovae in metal-poor stars  

E-Print Network [OSTI]

The unique elemental abundance pattern of the carbon-rich stars CS29498-043 and CS22949-037 is characterized by a large excess of magnesium and silicon in comparison with iron. This excess is investigated in the context of a supernova-induced star formation scenario, and it is concluded that these stars were born from the matter swept up by supernova remnants containing little iron and that such supernovae are similar to the least-luminous SNe ever observed, SNe 1997D and 1999br. Comparison of the observed abundance pattern in iron-group elements of subluminous supernovae with those of other supernovae leads to an intriguing implication for explosion, nucleosynthesis, and mixing in supernovae. The observed invariance of these ratios can not be accounted for by a spherically symmetric supernova model.

Takuji Tsujimoto; Toshikazu Shigeyama

2003-01-14T23:59:59.000Z

55

Rates and progenitors of type Ia supernovae  

E-Print Network [OSTI]

Supernovae . . . . . . . . . . . . . . . . . . . .Supernovae Found 5.1 Introduction . . . . . . . . . . . .1.2 Non-Type Ia Supernovae . . . . . . . . . . . . . . . 1.3

Wood-Vasey, William Michael

2004-01-01T23:59:59.000Z

56

From SupernovaeFrom Supernovae to Inflationto Inflation  

E-Print Network [OSTI]

From SupernovaeFrom Supernovae to Inflationto Inflation Katsuhiko SatoKatsuhiko Sato 1)Department.4. NucleosynthesisNucleosynthesis in supernovaein supernovae II.II. ParticleParticle cosmologycosmology andand Early

Yamamoto, Hirosuke

57

Neutrino flavor transformation in core-collapse supernovae  

E-Print Network [OSTI]

in Supernovae . . . . . . . . . . . . . . . . . . . . .Collapse Supernovae . . . . . . . . . . . . . . . . . . . .Mechanisms of Core-Collapse Supernovae: Simulation Results

Cherry, John F.; Cherry, John F.

2012-01-01T23:59:59.000Z

58

Conformally Friedmann-Lemaitre-Robertson-Walker cosmologies  

E-Print Network [OSTI]

In a universe where, according to the standard cosmological models, some 97% of the total mass-energy is still "missing in action" it behooves us to spend at least a little effort critically assessing and exploring radical alternatives. Among possible, (dare we say plausible), nonstandard but superficially viable models, those spacetimes conformal to the standard Friedmann-Lemaitre-Robertson-Walker class of cosmological models play a very special role --- these models have the unique and important property of permitting large non-perturbative geometric deviations from Friedmann-Lemaitre-Robertson-Walker cosmology without unacceptably distorting the cosmic microwave background. Performing a "cosmographic" analysis, (that is, temporarily setting aside the Einstein equations, since the question of whether or not the Einstein equations are valid on galactic and cosmological scales is essentially the same question as whether or not dark matter/dark energy actually exist), and using both supernova data and informat...

Visser, Matt

2015-01-01T23:59:59.000Z

59

Observational constraints on late-time {lambda}(t) cosmology  

SciTech Connect (OSTI)

The cosmological constant {lambda}, i.e., the energy density stored in the true vacuum state of all existing fields in the Universe, is the simplest and the most natural possibility to describe the current cosmic acceleration. However, despite its observational successes, such a possibility exacerbates the well-known {lambda} problem, requiring a natural explanation for its small, but nonzero, value. In this paper we study cosmological consequences of a scenario driven by a varying cosmological term, in which the vacuum energy density decays linearly with the Hubble parameter, {lambda}{proportional_to}H. We test the viability of this scenario and study a possible way to distinguish it from the current standard cosmological model by using recent observations of type Ia supernova (Supernova Legacy Survey Collaboration), measurements of the baryonic acoustic oscillation from the Sloan Digital Sky Survey, and the position of the first peak of the cosmic microwave background angular spectrum from the three-year Wilkinson Microwave Anisotropy Probe.

Carneiro, S.; Pigozzo, C. [Instituto de Fisica, Universidade Federal da Bahia, Salvador-BA, 40210-340 (Brazil); Dantas, M. A. [Departamento de Astronomia, Observatorio Nacional, Rio de Janeiro-RJ, 20921-400 (Brazil); Alcaniz, J. S. [Departamento de Astronomia, Observatorio Nacional, Rio de Janeiro-RJ, 20921-400 (Brazil); Instituto Nacional de Pesquisas Espaciais/CRN, 59076-740, Natal-RN (Brazil)

2008-04-15T23:59:59.000Z

60

Supernovae. Part I: The events  

E-Print Network [OSTI]

Barkat, Z. , 1977, in Supernovae, edited by D. N. Schramm {Sci. Rev. 27, Canal, Supernovae. R. A. , 1981f, in NATO81.C. B. , Ed. , 1974, Supernovae and Their Remnants,

Trimble, V

1982-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

THE BERKELEY AUTOMATED SUPERNOVA SEARCH  

E-Print Network [OSTI]

Dordrecht L . Rosino, in Supernovae, ed. D . Schramm, p.Texas Workshop on Type I Supernovae, ed. J . C . Wheeler, p.Studies Institute on Supernovae, (Reidel, Dordrecht 1981),

Kare, J.T.

2010-01-01T23:59:59.000Z

62

Laser Cosmology  

E-Print Network [OSTI]

Recent years have seen tremendous progress in our understanding of the cosmos, which in turn points to even deeper questions to be further addressed. Concurrently the laser technology has undergone dramatic revolutions, providing exciting opportunity for science applications. History has shown that the symbiosis between direct observations and laboratory investigation is instrumental in the progress of astrophysics. We believe that this remains true in cosmology. Current frontier phenomena related to particle astrophysics and cosmology typically involve one or more of the following conditions: (1) extremely high energy events; (2) very high density, high temperature processes; (3) super strong field environments. Laboratory experiments using high intensity lasers can calibrate astrophysical observations, investigate underlying dynamics of astrophysical phenomena, and probe fundamental physics in extreme limits. In this article we give an overview of the exciting prospect of laser cosmology. In particular, we showcase its unique capability of investigating frontier cosmology issues such as cosmic accelerator and quantum gravity.

Pisin Chen

2014-02-24T23:59:59.000Z

63

A Supernova Riddle  

E-Print Network [OSTI]

Analysis of the polarization of light from supernovae can reveal the shape and distribution of matter ejected from exploding stars. Here we review the young field of Type Ia supernova spectropolarimetry and critically evaluate, and place in context, the recent work of Wang et al. (2007, Science, 315, 212) in which a suggestive trend is found in data from 17 Type Ia events.

Douglas C. Leonard

2007-12-24T23:59:59.000Z

64

Supersymmetric quantum cosmological billiards  

SciTech Connect (OSTI)

D=11 supergravity near a spacelike singularity admits a cosmological billiard description based on the hyperbolic Kac-Moody group E{sub 10}. The quantization of this system via the supersymmetry constraint is shown to lead to wave functions involving automorphic (Maass wave) forms under the modular group W{sup +}(E{sub 10}) congruent with PSL{sub 2}(O) with Dirichlet boundary conditions on the billiard domain. A general inequality for the Laplace eigenvalues of these automorphic forms implies that the wave function of the Universe is generically complex and always tends to zero when approaching the initial singularity. We discuss possible implications of this result for the question of singularity resolution in quantum cosmology and comment on the differences with other approaches.

Kleinschmidt, Axel; Koehn, Michael; Nicolai, Hermann [Physique Theorique et Mathematique and International Solvay Institutes, Universite Libre de Bruxelles, Boulevard du Triomphe, ULB-CP231, BE-1050 Bruxelles (Belgium); Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, DE-14476 Golm (Germany)

2009-09-15T23:59:59.000Z

65

New approaches for modeling type Ia supernovae  

E-Print Network [OSTI]

runaway in Type Ia supernovae: How to run away? oIgnition in Type Ia Supernovae. II. A Three- dimensionalnumber modeling of type Ia supernovae. I. hydrodynamics.

Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

2007-01-01T23:59:59.000Z

66

Supernova Recognition using Support Vector Machines  

E-Print Network [OSTI]

pected to contain real supernovae. Astrophysicists who inObservational Evi- dence from Supernovae for an Acceleratingi.e. to ?nd all potential supernovae, while reducing the

Romano, Raquel A.; Aragon, Cecilia R.; Ding, Chris

2006-01-01T23:59:59.000Z

67

Black hole evolution: I. Supernova-regulated black hole growth  

E-Print Network [OSTI]

The growth of a supermassive black hole (BH) is determined by how much gas the host galaxy is able to feed it, which in turn is controlled by the cosmic environment, through galaxy mergers and accretion of cosmic flows that time how galaxies obtain their gas, but also by internal processes in the galaxy, such as star formation and feedback from stars and the BH itself. In this paper, we study the growth of a 10^12 Msun halo at z=2, which is the progenitor of an archetypical group of galaxies at z=0, and of its central BH by means of a high-resolution zoomed cosmological simulation, the Seth simulation. We study the evolution of the BH driven by the accretion of cold gas in the galaxy, and explore the efficiency of the feedback from supernovae (SNe). For a relatively inefficient energy input from SNe, the BH grows at the Eddington rate from early times, and reaches self-regulation once it is massive enough. We find that at early cosmic times z>3.5, efficient feedback from SNe forbids the formation of a settled...

Dubois, Yohan; Silk, Joseph; Devriendt, Julien; Slyz, Adrianne; Teyssier, Romain

2015-01-01T23:59:59.000Z

68

Evolution of density perturbations in decaying vacuum cosmology  

SciTech Connect (OSTI)

We study cosmological perturbations in the context of an interacting dark energy model, in which the cosmological term decays linearly with the Hubble parameter, with concomitant matter production. A previous joint analysis of the redshift-distance relation for type Ia supernovas, barionic acoustic oscillations, and the position of the first peak in the anisotropy spectrum of the cosmic microwave background has led to acceptable values for the cosmological parameters. Here we present our analysis of small perturbations, under the assumption that the cosmological term, and therefore the matter production, are strictly homogeneous. Such a homogeneous production tends to dilute the matter contrast, leading to a late-time suppression in the power spectrum. Nevertheless, an excellent agreement with the observational data can be achieved by using a higher matter density as compared to the concordance value previously obtained. This may indicate that our hypothesis of homogeneous matter production must be relaxed by allowing perturbations in the interacting cosmological term.

Borges, H. A.; Pigozzo, C. [Instituto de Fisica, Universidade Federal da Bahia, Salvador, BA (Brazil); Carneiro, S. [Instituto de Fisica, Universidade Federal da Bahia, Salvador, BA (Brazil); International Centre for Theoretical Physics, Trieste (Italy); Fabris, J. C. [Institut d'Astrophysique de Paris, Paris (France)

2008-02-15T23:59:59.000Z

69

"Cosmologists have used these supernovae very pro-  

E-Print Network [OSTI]

--the type II supernovae--presents theorists with another set of challenges. A type II supernova pops off

Zhang, Yi

70

Cosmic Supernova Rate History and Type Ia Supernova Progenitors  

E-Print Network [OSTI]

Adopting a single degenerate scenario for Type Ia supernova progenitors with the metallicity effect, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in spiral and elliptical galaxies, and compare with the recent observational data up to z ~ 0.55.

Chiaki Kobayashi; Ken'ichi Nomoto; Takuji Tsujimoto

2001-02-14T23:59:59.000Z

71

Accelerated expansion from cosmological holography  

E-Print Network [OSTI]

It is shown that holographic cosmology implies an evolving Hubble radius $c^{-1}\\dot{R}_H = -1 + 3\\Omega_m$ in the presence of a dimensionless matter density $\\Omega_m$ scaled to the closure density $3H^2/8\\pi G$, where $c$ denotes the velocity of light and $H$ and $G$ denote the Hubble parameter and Newton's constant. It reveals a dynamical dark energy and a sixfold increase in gravitational attraction to matter on the scale of the Hubble acceleration. It reproduces the transition redshift $z_t\\simeq 0.4$ to the present epoch of accelerated expansion and is consistent with $(q_0,(dq/dz)_0)$ of the deceleration parameter $q(z)=q_0+(dq/dz)_0z$ observed in Type Ia supernovae.

van Putten, Maurice H P M

2015-01-01T23:59:59.000Z

72

Type Ia Supernova Carbon Footprints  

E-Print Network [OSTI]

We present convincing evidence of unburned carbon at photospheric velocities in new observations of 5 Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 d relative to maximum. Detections are based on the presence of relatively strong C II 6580 absorption "notches" in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the 5 SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibits high-velocity (v > 20,000 km/s) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broad band light curve/color behavior: Three of the 5 have relatively narrow light curves but also blue colors, and a fourth may be a dust-reddened member of this family. Accounting for signal-to-noise and phase, we ...

Thomas, R C; Aragon, C; Antilogus, P; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Hsiao, E Y; Kerschhaggl, M; Kowalski, M; Loken, S; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Rubin, D; Runge, K; Scalzo, R; Smadja, G; Tao, C; Weaver, B A; Wu, C; Brown, P J; Milne, P A

2011-01-01T23:59:59.000Z

73

Essential ingredients in core-collapse supernovae  

SciTech Connect (OSTI)

Carrying 10{sup 44} joules of kinetic energy and a rich mix of newly synthesized atomic nuclei, core-collapse supernovae are the preeminent foundries of the nuclear species which make up our solar system and ourselves. Signaling the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae combine physics over a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale) down to femtometer-scale nuclear reactions. We will discuss our emerging understanding of the convectively-unstable, neutrino-driven explosion mechanism, based on increasingly realistic neutrino radiation hydrodynamic simulations that include progressively better nuclear and particle physics. Multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have recently motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of the births of neutron stars and the supernovae that result. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

Hix, W. Raphael [Physics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6354 (United States) [Physics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6354 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Lentz, Eric J.; Chertkow, M. Austin; Harris, J. Austin [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States)] [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Endeve, Eirik [Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6008 (United States)] [Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6008 (United States); Baird, Mark [Reactor and Nuclear Systems Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6003 (United States)] [Reactor and Nuclear Systems Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6003 (United States); Messer, O. E. Bronson [Physics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6354 (United States) [Physics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6354 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge TN 37831-6008 (United States); Mezzacappa, Anthony [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States) [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Joint Institute for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6173 (United States); Bruenn, Stephen [Department of Physics, Florida Atlantic University, 777 W Glades Road, Boca Raton, FL 33431-0991 (United States)] [Department of Physics, Florida Atlantic University, 777 W Glades Road, Boca Raton, FL 33431-0991 (United States); Blondin, John [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States)] [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States)

2014-04-15T23:59:59.000Z

74

Cosmological bounds on oscillating dark energy models  

E-Print Network [OSTI]

We study some cosmological constraints on the two phenomenological models of oscillating dark energy. In these scenarios, the equation of state of dark energy varies periodically and may provide a way to unify the early acceleration (inflation) and the late time acceleration of the universe. These models give also an effective way to tackle the so-called cosmic coincidence problem. We examine observational constraints on this class of models from the latest observational data including the \\emph{gold} sample of 182 type Ia supernovae, the CMB shift parameter $R$ and the BAO measurements from the Sloan Digital Sky Survey.

Deepak Jain; Abha Dev; J. S. Alcaniz

2007-09-26T23:59:59.000Z

75

DUST IN A TYPE Ia SUPERNOVA PROGENITOR: SPITZER SPECTROSCOPY OF KEPLER'S SUPERNOVA REMNANT  

SciTech Connect (OSTI)

Characterization of the relatively poorly understood progenitor systems of Type Ia supernovae is of great importance in astrophysics, particularly given the important cosmological role that these supernovae play. Kepler's supernova remnant, the result of a Type Ia supernova, shows evidence for an interaction with a dense circumstellar medium (CSM), suggesting a single-degenerate progenitor system. We present 7.5-38 {mu}m infrared (IR) spectra of the remnant, obtained with the Spitzer Space Telescope, dominated by emission from warm dust. Broad spectral features at 10 and 18 {mu}m, consistent with various silicate particles, are seen throughout. These silicates were likely formed in the stellar outflow from the progenitor system during the asymptotic giant branch stage of evolution, and imply an oxygen-rich chemistry. In addition to silicate dust, a second component, possibly carbonaceous dust, is necessary to account for the short-wavelength Infrared Spectrograph and Infrared Array Camera data. This could imply a mixed chemistry in the atmosphere of the progenitor system. However, non-spherical metallic iron inclusions within silicate grains provide an alternative solution. Models of collisionally heated dust emission from fast shocks (>1000 km s{sup -1}) propagating into the CSM can reproduce the majority of the emission associated with non-radiative filaments, where dust temperatures are {approx}80-100 K, but fail to account for the highest temperatures detected, in excess of 150 K. We find that slower shocks (a few hundred km s{sup -1}) into moderate density material (n{sub 0} {approx} 50-250 cm{sup -3}) are the only viable source of heating for this hottest dust. We confirm the finding of an overall density gradient, with densities in the north being an order of magnitude greater than those in the south.

Williams, Brian J.; Borkowski, Kazimierz J.; Reynolds, Stephen P. [Physics Department, North Carolina State University, Raleigh, NC 27695-8202 (United States); Ghavamian, Parviz [Department of Physics, Astronomy, and Geosciences, Towson University, Towson, MD 21252 (United States); Blair, William P. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Long, Knox S. [STScI, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Sankrit, Ravi, E-mail: brian.j.williams@nasa.gov [SOFIA/USRA, NASA Ames Research Center, M/S N211-3, Moffett Field, CA 94035 (United States)

2012-08-10T23:59:59.000Z

76

On an Alternative Cosmology  

E-Print Network [OSTI]

The suggested alternative cosmology is based on the idea of barion symmetric universe, in which our home universe is a representative of multitude of typical matter and antimatter universes. This alternative concept gives a physically reasonable explanation of all major problems of the Standard Cosmological Model. Classification Code MSC: Cosmology 524.8 Key words: standard cosmological model, alternative cosmology, barionic symmetry, typical universe, quasars, cosmic rays.

A. Vankov

1998-11-10T23:59:59.000Z

77

EUNHA: a new cosmological hydro simulation code  

E-Print Network [OSTI]

We have developed a parallel cosmological hydrodynamic simulation code designed for the study of formation and evolution of cosmological structures. The gravitational force is calculated using the TreePM method and the hydrodynamics is implemented based on the smoothed particle hydrodynamics. The initial displacement and velocity of simulation particles are calculated according to second-order linear perturbation theory using the power spectra of dark matter and baryonic matter. The initial background temperature is given by Recfast and the temperature uctuations at the initial particle position are determined by the adiabatic model. We use a time-limiter scheme over the individual time steps to capture shock-fronts and to ease the time-step tension between the shock and preshock particles. We also include the astrophysical gas processes of radiative heating/cooling, star formation, metal enrichment, and supernova feedback. We have tested the code in several standard cases such as one-dimensional Riemann prob...

Shina, Jihye; Kim, Sungsoo S; Park, Changbom

2014-01-01T23:59:59.000Z

78

The binary progenitor of Tycho Brahe's 1572 supernova  

E-Print Network [OSTI]

The brightness of type Ia supernovae, and their homogeneity as a class, makes them powerful tools in cosmology, yet little is known about the progenitor systems of these explosions. They are thought to arise when a white dwarf accretes matter from a companion star, is compressed and undergoes a thermonuclear explosion Unless the companion star is another white dwarf (in which case it should be destroyed by the mass-transfer process itself), it should survive and show distinguishing properties. Tycho's supernova is one of the only two type Ia supernovae observed in our Galaxy, and so provides an opportunity to address observationally the identification of the surviving companion. Here we report a survey of the central region of its remnant, around the position of the explosion, which excludes red giants as the mass donor of the exploding white dwarf. We found a type G0--G2 star, similar to our Sun in surface temperature and luminosity (but lower surface gravity), moving at more than three times the mean velocity of the stars at that distance, which appears to be the surviving companion of the supernova.

Pilar Ruiz-Lapuente; Fernando Comeron; Javier Mendez; Ramon Canal; Stephen J. Smartt; Alexei V. Filippenko; Robert L. Kurucz; Ryan Chornock; Ryan J. Foley; Vallery Stanishev; Rodrigo Ibata

2004-10-28T23:59:59.000Z

79

The type Ia supernovae and the Hubble's constant  

E-Print Network [OSTI]

The Hubble's constant is usually surmised to be a constant; but the experiments show a large spread and conflicting estimates. According to the plasma-redshift theory, the Hubble's constant varies with the plasma densities along the line of sight. It varies then slightly with the direction and the distance to a supernova and a galaxy. The relation between the magnitudes of type Ia supernovae and their observed redshifts results in an Hubble's constant with an average value in intergalactic space of 59.44 km per s per Mpc. The standard deviation from this average value is only 0.6 km per s per Mpc, but the standard deviation in a single measurement is about 8.2 km per s per Mpc. These deviations do not include possible absolute calibration errors. The experiments show that the Hubble's constant varies with the intrinsic redshifts of the Milky Way galaxy and the host galaxies for type Ia supernovae, and that it varies with the galactic latitude. These findings support the plasma-redshift theory and contradict the contemporary big-bang theory. Together with the previously reported absence of time dilation in type Ia supernovae measurements, these findings have profound consequences for the standard cosmological theory.

Ari Brynjolfsson

2004-07-20T23:59:59.000Z

80

High Rate for Type IC Supernovae  

E-Print Network [OSTI]

Wheeler, J. C. 1990, in Supernovae, ed. A. G. Petschek (New4959. Tamrnann, G. A. 1977, in Supernovae, ed. D. Schramm (Wheeler, J. C. 1990, in Supernovae, ed. J. C. Wheeler, T.

Muller, R.A.

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

1987A: The greatest supernova since Kepler  

E-Print Network [OSTI]

Woosley, S. E. , 1988b, in Supernovae 19873 in the LargeGalactic Nuclei, and Supernovae, edited by S. Hayakawa andGalactic nuclei, and Supernovae, edited by S. Hayakawa and

Trimble, V

1988-01-01T23:59:59.000Z

82

Overview of the nearby supernova factory  

E-Print Network [OSTI]

from 42 High-Redshift Supernovae,” Astrophys J. 517, pp.Observational Evidence from Supernovae for an AcceleratingCalan/Tololo Type Ia Supernovae,” Astron. J. 112, p. 2391,

2002-01-01T23:59:59.000Z

83

A Massive Stellar Burst Before the Supernova  

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

Burst Before the Supernova February 6, 2013 | Tags: Carver, High Energy Physics, supernovae Contact: Linda Vu, lvu@lbl.gov, +1 510 495 2402 An automated supernova hunt is...

84

Learning from the scatter in type Ia supernovae  

SciTech Connect (OSTI)

Type Ia Supernovae are standard candles so their mean apparent magnitude has been exploited to learn about the redshift-distance relationship. Besides intrinsic scatter in this standard candle, additional scatter is caused by gravitational magnification by large scale structure. Here we probe the dependence of this dispersion on cosmological parameters and show that information about the amplitude of clustering, {sigma}{sub 8}, is contained in the scatter. In principle, it will be possible to constrain {sigma}{sub 8} to within 5% with observations of 2000 Type Ia Supernovae. We identify three sources of systematic error - evolution of intrinsic scatter, baryon contributions to lensing, and non-Gaussianity of lensing - which will make this measurement difficult.

Dodelson, Scott [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States); Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637-1433 (United States); Vallinotto, Alberto [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States); Department of Physics, The University of Chicago, Chicago, Illinois 60637-1433 (United States)

2006-09-15T23:59:59.000Z

85

Snapping Supernovae at z>1.7  

E-Print Network [OSTI]

redshift supernovae — both thermonuclear and core collapse —between core-collapse and thermonuclear supernovae (Iben &such SNe — both thermonuclear and core collapse — will be

Aldering, Greg

2009-01-01T23:59:59.000Z

86

Cosmology with dark energy decaying through its chemical-potential contribution  

E-Print Network [OSTI]

The consideration of dark energy's quanta, required also by thermodynamics, introduces its chemical potential into the cosmological equations. Isolating its main contribution, we obtain solutions with dark energy decaying to matter or radiation. When dominant, their energy densities tend asymptotically to a constant ratio, explaining today's dark energy-dark matter coincidence, and in agreement with supernova redshift data.

J. Besprosvany

2007-12-29T23:59:59.000Z

87

LXCDM cosmologies: solving the cosmological coincidence problem?  

E-Print Network [OSTI]

We explore the possibility of having a composite (self-conserved) dark energy (DE) whose dynamics is controlled by the quantum running of the cosmological parameters. We find that within this scenario it is feasible to find an explanation for the cosmological coincidence problem and at the same time a good qualitative description of the present data.

Javier Grande; Joan Sola; Hrvoje Stefancic

2006-09-25T23:59:59.000Z

88

Cosmological model-independent Gamma-ray bursts calibration and its cosmological constraint to dark energy  

SciTech Connect (OSTI)

As so far, the redshift of Gamma-ray bursts (GRBs) can extend to z ? 8 which makes it as a complementary probe of dark energy to supernova Ia (SN Ia). However, the calibration of GRBs is still a big challenge when they are used to constrain cosmological models. Though, the absolute magnitude of GRBs is still unknown, the slopes of GRBs correlations can be used as a useful constraint to dark energy in a completely cosmological model independent way. In this paper, we follow Wang's model-independent distance measurement method and calculate their values by using 109 GRBs events via the so-called Amati relation. Then, we use the obtained model-independent distances to constrain ?CDM model as an example.

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

2012-04-01T23:59:59.000Z

89

Collective neutrino oscillations in supernovae  

SciTech Connect (OSTI)

In a dense neutrino medium neutrinos can experience collective flavor transformation through the neutrino-neutrino forward scattering. In this talk we present some basic features of collective neutrino flavor transformation in the context in core-collapse supernovae. We also give some qualitative arguments for why and when this interesting phenomenon may occur and how it may affect supernova nucleosynthesis.

Duan, Huaiyu [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States)

2014-06-24T23:59:59.000Z

90

Supernova Neutrinos Detection On Earth  

E-Print Network [OSTI]

In this paper, we first discuss the detection of supernova neutrino on Earth. Then we propose a possible method to acquire information about $\\theta_{13}$ smaller than $1.5^\\circ$ by detecting the ratio of the event numbers of different flavor supernova neutrinos. Such an sensitivity cannot yet be achieved by the Daya Bay reactor neutrino experiment.

Xin-Heng Guo; Ming-Yang Huang; Bing-Lin Young

2009-05-12T23:59:59.000Z

91

Nucleosynthesis in Type II Supernovae  

E-Print Network [OSTI]

Presupernova evolution and explosive nucleosynthesis in massive stars for main-sequence masses from 13 $M_\\odot$ to 70 $M_\\odot$ are calculated. We examine the dependence of the supernova yields on the stellar mass, $^{12}C(\\alpha, \\gamma) ^{16}O}$ rate, and explosion energy. The supernova yields integrated over the initial mass function are compared with the solar abundances.

K. Nomoto; M. Hashimoto; T. Tsujimoto; F. -K. Thielemann; N. Kishimoto; Y. Kubo

1997-06-03T23:59:59.000Z

92

Supernova constraints on multi-coupled dark energy  

SciTech Connect (OSTI)

The persisting consistency of ever more accurate observational data with the predictions of the standard ?CDM cosmological model puts severe constraints on possible alternative scenarios, but still does not shed any light on the fundamental nature of the cosmic dark sector. As large deviations from a ?CDM cosmology are ruled out by data, the path to detect possible features of alternative models goes necessarily through the definition of cosmological scenarios that leave almost unaffected the background and — to a lesser extent — the linear perturbations evolution of the universe. In this context, the Multi-coupled DE (McDE) model was proposed by Baldi [9] as a particular realization of an interacting Dark Energy field characterized by an effective screening mechanism capable of suppressing the effects of the coupling at the background and linear perturbation level. In the present paper, for the first time, we challenge the McDE scenario through a direct comparison with real data, in particular with the luminosity distance of Type Ia supernovae. By studying the existence and stability conditions of the critical points of the associated background dynamical system, we select only the cosmologically consistent solutions, and confront their background expansion history with data. Confirming previous qualitative results, the McDE scenario appears to be fully consistent with the adopted sample of Type Ia supernovae, even for coupling values corresponding to an associated scalar fifth-force about four orders of magnitude stronger than standard gravity. Our analysis demonstrates the effectiveness of the McDE background screening, and shows some new non-trivial asymptotic solutions for the future evolution of the universe. Clearly, linear perturbation data and, even more, nonlinear structure formation properties are expected to put much tighter constraints on the allowed coupling range. Nonetheless, our results show how the background expansion history might be highly insensitive to the fundamental nature and to the internal complexity of the dark sector.

Piloyan, Arpine [Yerevan State University, Alex Manoogian 1, Yerevan 0025 (Armenia); Marra, Valerio; Amendola, Luca [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Baldi, Marco, E-mail: arpine.piloyan@ysu.am, E-mail: valerio.marra@me.com, E-mail: marco.baldi5@unibo.it, E-mail: l.amendola@thphys.uni-heidelberg.de [Dipartimento di Fisica e Astronomia, Universitŕ di Bologna, Viale C. Berti-Pichat 6/2, I-40127, Bologna (Italy)

2013-07-01T23:59:59.000Z

93

Nuclear astrophysics of supernovae  

SciTech Connect (OSTI)

In this paper, I'll give a general introduction to Supernova Theory, beginning with the presupernova evolution and ending with the later stages of the explosion. This will be distilled from a colloquium type of talk. It is necessary to have the whole supernova picture in one's mind's eye when diving into some of its nooks and crannies, as it is quite a mess of contradictory ingredients. We will have some discussion of supernova 1987a, but will keep our discussion more general. Second, we'll look at the infall and bounce of the star, seeing why it goes unstable, what dynamics it follows as it collapses, and how and why it bounces back. From there, we will go on to look at the equation of state (EOS) in more detail. We'll consider the cases T = 0 and T > 0. We'll focus on /rho/ < /rho//sub 0/, and then /rho/ > /rho//sub 0/ and the EOS of neutron stars, and whether or not they contain cores of strange matter. There are many things we could discuss here and not enough time. If I had more lectures, the remaining time would focus on two more questions of special interest to nuclear physicists: the electron capture reactions and neutrino transport. If time permitted, we'd have some discussion of the nucleosynthetic reactions in the explosion's debris as well. However, we cannot cover such material adequately, and I have chosen these topics because they are analytically tractable, pedagogically useful, and rather important. 23 refs., 14 figs., 3 tabs.

Cooperstein, J.

1988-01-01T23:59:59.000Z

94

First-Year Spectroscopy for the SDSS-II Supernova Survey  

SciTech Connect (OSTI)

This paper presents spectroscopy of supernovae discovered in the first season of the Sloan Digital Sky Survey-II Supernova Survey. This program searches for and measures multi-band light curves of supernovae in the redshift range z = 0.05-0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the supernova population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our supernova spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the supernova and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host galaxy contamination existing in the majority of our SN spectra.

Zheng, Chen; Romani, Roger W.; Sako, Masao; Marriner, John; Bassett, Bruce; Becker, Andrew; Choi, Changsu; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Dilday, Ben; Doi, Mamoru; Frieman, Joshua A.; Garnavich, Peter M.; Hogan, Craig J.; Holtzman, Jon; Im, Myungshin; Jha, Saurabh; Kessler, Richard; Konishi, Kohki; Lampeitl, Hubert

2008-03-25T23:59:59.000Z

95

Evolution of density perturbations in decaying vacuum cosmology: The case of nonzero perturbations in the cosmological term  

SciTech Connect (OSTI)

We extend the results of a previous paper where a model of interacting dark energy, with a cosmological term decaying linearly with the Hubble parameter, is tested against the observed mass power spectrum. In spite of the agreement with observations of type Ia supernovas, baryonic acoustic oscillations, and the cosmic microwave background, we had shown previously that no good concordance is achieved if we include the mass power spectrum. However, our analysis was based on the ad hoc assumption that the interacting cosmological term is strictly homogeneous. Now we perform a more complete analysis, by perturbing such a term. Although our conclusions are still based on a particular, scale-invariant choice of the primordial spectrum of dark energy perturbations, we show that a cosmological term decaying linearly with the Hubble parameter is indeed disfavored as compared to the standard model.

Borges, H. A. [Instituto de Fisica, Universidade Federal da Bahia, Salvador, BA (Brazil); Centro de Formacao de Professores, Universidade Federal do Reconcavo da Bahia, Amargosa, BA (Brazil); Carneiro, S. [Instituto de Fisica, Universidade Federal da Bahia, Salvador, BA (Brazil); Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, London (United Kingdom); Fabris, J. C. [Departamento de Fisica, Universidade Federal do Espirito Santo, Vitoria, ES (Brazil); Institut d'Astrophysique de Paris, Paris (France)

2008-12-15T23:59:59.000Z

96

Long Gamma-Ray Bursts Calibrated by Pade Method and Constraints on Cosmological Models  

E-Print Network [OSTI]

Gamma-ray bursts (GRBs) are among the most powerful sources in the universe. In the recent years, GRBs have been proposed as a complementary probe to type Ia supernovae (SNIa). However, as is well known, there is a circularity problem in the use of GRBs to study cosmology. In this work, based on the Pad\\'e approximant, we propose a new cosmology-independent method to calibrate GRBs. We consider a sample consisting 138 long GRBs and obtain 79 calibrated long GRBs at high redshift $z>1.4$ (named Mayflower sample) which can be used to constrain cosmological models without the circularity problem. Then, we consider the constraints on several cosmological models with these 79 calibrated GRBs and other observational data. We show that GRBs are competent to be a complementary probe to the other well-established cosmological observations.

Liu, Jing

2014-01-01T23:59:59.000Z

97

Long Gamma-Ray Bursts Calibrated by Pade Method and Constraints on Cosmological Models  

E-Print Network [OSTI]

Gamma-ray bursts (GRBs) are among the most powerful sources in the universe. In the recent years, GRBs have been proposed as a complementary probe to type Ia supernovae (SNIa). However, as is well known, there is a circularity problem in the use of GRBs to study cosmology. In this work, based on the Pad\\'e approximant, we propose a new cosmology-independent method to calibrate GRBs. We consider a sample consisting 138 long GRBs and obtain 79 calibrated long GRBs at high redshift $z>1.4$ (named Mayflower sample) which can be used to constrain cosmological models without the circularity problem. Then, we consider the constraints on several cosmological models with these 79 calibrated GRBs and other observational data. We show that GRBs are competent to be a complementary probe to the other well-established cosmological observations.

Jing Liu; Hao Wei

2014-10-15T23:59:59.000Z

98

A Probabilistic Approach to Classifying Supernovae Using Photometric Information  

E-Print Network [OSTI]

ciency of selecting type Ia supernovae for p cut = 0.98 (weApproach to Classifying Supernovae Using Photometricstudies). Subject headings: supernovae: general Introduction

Kuznetsova, Natalia V.; Connolly, Brian M.

2008-01-01T23:59:59.000Z

99

Pineapples and crabs: When young supernova remnants were even younger  

E-Print Network [OSTI]

1977. The Historical Supernovae, Oxford, Pergamon 7 Trimble,C.B. Cosmovici (Ed. ) Supernovae and their Remnants, Reidel,C.B. Cosmovici (ed. ) Supernovae and their Remnants, Reidel,

Trimble, V

2001-01-01T23:59:59.000Z

100

Type Ia Supernova Hubble Residuals and Host-Galaxy Properties  

E-Print Network [OSTI]

magnitudes of type Ia supernovae from multi-band lightsuch an analysis on the supernovae of the Nearby Supernovaheadings: distance scale, supernovae: general 1 Physics

Kim, A. G.

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

A fast contour descriptor algorithm for supernova image classification  

E-Print Network [OSTI]

from 42 High-Redshift Supernovae," Astrophysical JournalObservational Evidence from Supernovae for an Acceleratingand Progenitors of Type Ia Supernovae," PhD dissertation,

Aragon, Cecilia R.; Aragon, David Bradburn

2006-01-01T23:59:59.000Z

102

K-corrections and spectral templates of Type Ia supernovae  

E-Print Network [OSTI]

templates of Type Ia supernovae E. Y. Hsiao 1 , A. Conleyobservations of low-redshift supernovae are less a?ected byobservations, stars: supernovae Department of Physics and

Hsiao, E. Y.

2008-01-01T23:59:59.000Z

103

Prospective Type Ia supernova surveys from Dome A  

E-Print Network [OSTI]

time series of ?1000 z supernovae. These can serve tocapable of discovering supernovae shortly after explosion§4. 2. Low-Redshift Supernovae A nearby sample is essential

Kim, A.

2010-01-01T23:59:59.000Z

104

Robust model comparison disfavors power law cosmology  

E-Print Network [OSTI]

Late-time power law expansion has been proposed as an alternative to the standard cosmological model and shown to be consistent with some low-redshift data. We test power law expansion against the standard flat $\\Lambda$CDM cosmology using goodness-of-fit and model comparison criteria. We consider Type Ia supernova (SN Ia) data from two current compilations (Union2.1 and JLA) along with a current set of baryon acoustic oscillation (BAO) measurements that includes the high-redshift Lyman-$\\alpha$ forest measurements from BOSS quasars. We find that neither power law expansion nor $\\Lambda$CDM is strongly preferred over the other when the SN Ia and BAO data are analyzed separately but that power law expansion is strongly disfavored by the combination. We treat the $R_\\text{h} = ct$ cosmology (a constant rate of expansion) separately and find that it is conclusively disfavored by all combinations of data that include SN Ia observations and a poor overall fit when systematic errors in the SN Ia measurements are ig...

Shafer, Daniel L

2015-01-01T23:59:59.000Z

105

Effect of nuclear structure on Type Ia supernova nucleosynthesis  

E-Print Network [OSTI]

The relationship among nuclear structure, the weak processes in nuclei, and astrophysics becomes quite apparent in supernova explosion and nucleosynthesis studies. In this brief article, I report on progress made in the last few years on calculating electron capture and beta-decay rates in iron-group nuclei. I also report on applications of these rates to Type-Ia nucleosynthesis studies.

D. J. Dean

2000-12-08T23:59:59.000Z

106

Nearby Supernova Factory Observations of SN 2006D: On Sporadic Carbon Signatures in Early Type Ia Supernova Spectra  

E-Print Network [OSTI]

with low volume-?lling factor. Subject headings: supernovae:general — supernovae: individual (SN 2006D)Introduction Type Ia supernovae (SNe Ia) make valuable

2006-01-01T23:59:59.000Z

107

FINDING THE FIRST COSMIC EXPLOSIONS. I. PAIR-INSTABILITY SUPERNOVAE  

SciTech Connect (OSTI)

The first stars are the key to the formation of primitive galaxies, early cosmological reionization and chemical enrichment, and the origin of supermassive black holes. Unfortunately, in spite of their extreme luminosities, individual Population III (Pop III) stars will likely remain beyond the reach of direct observation for decades to come. However, their properties could be revealed by their supernova explosions, which may soon be detected by a new generation of near-IR (NIR) observatories such as JWST and WFIRST. We present light curves and spectra for Pop III pair-instability supernovae calculated with the Los Alamos radiation hydrodynamics code RAGE. Our numerical simulations account for the interaction of the blast with realistic circumstellar envelopes, the opacity of the envelope, and Lyman absorption by the neutral intergalactic medium at high redshift, all of which are crucial to computing the NIR signatures of the first cosmic explosions. We find that JWST will detect pair-instability supernovae out to z ?> 30, WFIRST will detect them in all-sky surveys out to z ? 15-20, and LSST and Pan-STARRS will find them at z ?< 7-8. The discovery of these ancient explosions will probe the first stellar populations and reveal the existence of primitive galaxies that might not otherwise have been detected.

Whalen, Daniel J.; Smidt, Joseph; Lovekin, C. C. [T-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Even, Wesley; Fryer, Chris L. [CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Frey, Lucille H. [HPC-3, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Johnson, Jarrett L.; Hungerford, Aimee L. [XTD-6, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Stiavelli, Massimo [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Holz, Daniel E. [Enrico Fermi Institute, Department of Physics, and Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Heger, Alexander [Monash Centre for Astrophysics, Monash University, Victoria 3800 (Australia); Woosley, S. E. [Department of Astronomy and Astrophysics, UCSC, Santa Cruz, CA 95064 (United States)

2013-11-10T23:59:59.000Z

108

The binary progenitor of Tycho Brahe's 1572 supernova  

E-Print Network [OSTI]

The brightness of type Ia supernovae, and their homogeneity as a class, makes them powerful tools in cosmology, yet little is known about the progenitor systems of these explosions. They are thought to arise when a white dwarf accretes matter from a companion star, is compressed and undergoes a thermonuclear explosion Unless the companion star is another white dwarf (in which case it should be destroyed by the mass-transfer process itself), it should survive and show distinguishing properties. Tycho's supernova is one of the only two type Ia supernovae observed in our Galaxy, and so provides an opportunity to address observationally the identification of the surviving companion. Here we report a survey of the central region of its remnant, around the position of the explosion, which excludes red giants as the mass donor of the exploding white dwarf. We found a type G0--G2 star, similar to our Sun in surface temperature and luminosity (but lower surface gravity), moving at more than three times the mean veloci...

Ruiz-Lapuente, P; Méndez, J; Canal, R; Smartt, S J; Filippenko, A V; Kurucz, R L; Chornock, R; Foley, R J; Stanishev, V; Ibata, R; Ruiz-Lapuente, Pilar; Comeron, Fernando; Mendez, Javier; Canal, Ramon; Smartt, Stephen J.; Filippenko, Alexei V.; Kurucz, Robert L.; Chornock, Ryan; Foley, Ryan J.; Stanishev, Vallery; Ibata, Rodrigo

2004-01-01T23:59:59.000Z

109

A Second Poincare' Group  

E-Print Network [OSTI]

Solutions of the sourceless Einstein's equation with weak and strong cosmological constants are discussed by using In\\"on\\"u-Wigner contractions of the de Sitter groups and spaces. The more usual case corresponds to a weak cosmological-constant limit, in which the de Sitter groups are contracted to the Poincar\\'e group, and the de Sitter spaces are reduced to the Minkowski space. In the strong cosmological-constant limit, however, the de Sitter groups are contracted to another group which has the same abstract Lie algebra of the Poincar\\'e group, and the de Sitter spaces are reduced to a 4-dimensional cone-space of infinite scalar curvature, but vanishing Riemann and Ricci curvature tensors. In such space, the special conformal transformations act transitively, and the equivalence between inertial frames is that of special relativity.

R. Aldrovandi; J. G. Pereira

1998-09-21T23:59:59.000Z

110

Thermonuclear supernova models, and observations of Type Ia supernovae  

E-Print Network [OSTI]

In this paper, we review the present state of theoretical models of thermonuclear supernovae, and compare their predicitions with the constraints derived from observations of Type Ia supernovae. The diversity of explosion mechanisms usually found in one-dimensional simulations is a direct consequence of the impossibility to resolve the flame structure under the assumption of spherical symmetry. Spherically symmetric models have been successful in explaining many of the observational features of Type Ia supernovae, but they rely on two kinds of empirical models: one that describes the behaviour of the flame on the scales unresolved by the code, and another that takes account of the evolution of the flame shape. In contrast, three-dimensional simulations are able to compute the flame shape in a self-consistent way, but they still need a model for the propagation of the flame in the scales unresolved by the code. Furthermore, in three dimensions the number of degrees of freedom of the initial configuration of the white dwarf at runaway is much larger than in one dimension. Recent simulations have shown that the sensitivity of the explosion output to the initial conditions can be extremely large. New paradigms of thermonuclear supernovae have emerged from this situation, as the Pulsating Reverse Detonation. The resolution of all these issues must rely on the predictions of observational properties of the models, and their comparison with current Type Ia supernova data, including X-ray spectra of Type Ia supernova remnants.

E. Bravo; C. Badenes; D. Garcia-Senz

2004-12-07T23:59:59.000Z

111

RESULTS OF THE LICK OBSERVATORY SUPERNOVA SEARCH FOLLOW-UP PHOTOMETRY PROGRAM: BVRI LIGHT CURVES OF 165 TYPE Ia SUPERNOVAE  

SciTech Connect (OSTI)

We present BVRI light curves of 165 Type Ia supernovae (SNe Ia) from the Lick Observatory Supernova Search follow-up photometry program from 1998 through 2008. Our light curves are typically well sampled (cadence of 3-4 days) with an average of 21 photometry epochs. We describe our monitoring campaign and the photometry reduction pipeline that we have developed. Comparing our data set to that of Hicken et al., with which we have 69 overlapping supernovae (SNe), we find that as an ensemble the photometry is consistent, with only small overall systematic differences, although individual SNe may differ by as much as 0.1 mag, and occasionally even more. Such disagreement in specific cases can have significant implications for combining future large data sets. We present an analysis of our light curves which includes template fits of light-curve shape parameters useful for calibrating SNe Ia as distance indicators. Assuming the B - V color of SNe Ia at 35 days past maximum light can be presented as the convolution of an intrinsic Gaussian component and a decaying exponential attributed to host-galaxy reddening, we derive an intrinsic scatter of {sigma} = 0.076 {+-} 0.019 mag, consistent with the Lira-Phillips law. This is the first of two papers, the second of which will present a cosmological analysis of the data presented herein.

Ganeshalingam, Mohan; Li Weidong; Filippenko, Alexei V.; Anderson, Carmen; Foster, Griffin; Griffith, Christopher V.; Joubert, Niels; Leja, Joel; Macomber, Brent; Pritchard, Tyler; Thrasher, Patrick; Winslow, Dustin [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L.; Grigsby, Bryant J.; Lowe, Thomas B. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States)

2010-10-15T23:59:59.000Z

112

Summary of JD 9 supernovae: Past, present, and future  

E-Print Network [OSTI]

Summary of JD 9 Supernovae: past, present, and futureZwicky (separately! ) that supernovae could serve as better

Trimble, VL

2006-01-01T23:59:59.000Z

113

On the geometry of cosmological model building  

E-Print Network [OSTI]

This article analyzes the present anomalies of cosmology from the point of view of integrable Weyl geometry. It uses P.A.M. Dirac's proposal for a weak extension of general relativity, with some small adaptations. Simple models with interesting geometrical and physical properties, not belonging to the Friedmann-Lema\\^{\\i}tre class, are studied in this frame. Those with positive spatial curvature (Einstein-Weyl universes) go well together with observed mass density $\\Omega_m$, CMB, supernovae Ia data, and quasar frequencies. They suggest a physical role for an equilibrium state of the Maxwell field proposed by I.E. Segal in the 1980s (Segal background) and for a time invariant balancing condition of vacuum energy density. The latter leads to a surprising agreement with the BF-theoretical calculation proposed by C. Castro (2002).

Erhard Scholz

2005-11-21T23:59:59.000Z

114

Towards a Cosmological Hubble Diagram for Type II-PSupernovae  

SciTech Connect (OSTI)

We present the first high-redshift Hubble diagram for Type II-P supernovae (SNe II-P) based upon five events at redshift upto z {approx}0.3. This diagram was constructed using photometry from the Canada-France-Hawaii Telescope Supernova Legacy Survey and absorption line spectroscopy from the Keck observatory. The method used to measure distances to these supernovae is based on recent work by Hamuy&Pinto (2002) and exploits a correlation between the absolute brightness of SNeII-P and the expansion velocities derived from the minimum of the Fe II 516.9 nm P-Cygni feature observed during the plateau phases. We present three refinements to this method which significantly improve the practicality of measuring the distances of SNe II-P at cosmologically interesting redshifts. These are an extinction correction measurement based on the V-I colors at day 50, across-correlation measurement for the expansion velocity and the ability to extrapolate such velocities accurately over almost the entire plateau phase. We apply this revised method to our dataset of high-redshift SNe II-P and find that the resulting Hubble diagram has a scatter of only 0.26 magnitudes, thus demonstrating the feasibility of measuring the expansion history, with present facilities, using a method independent of that based upon supernovae of Type Ia.

Nugent, Peter; Sullivan, Mark; Ellis, Richard; Gal-Yam, Avishay; Leonard, Douglas C.; Howell, D. Andrew; Astier, Pierre; Carlberg, RaymondG.; Conley, Alex; Fabbro, Sebastien; Fouchez, Dominique; Neill, James D.; Pain, Reynald; Perrett, Kathy; Pritchet, Chris J; Regnault, Nicolas

2006-03-20T23:59:59.000Z

115

Supernova Remnants And GLAST  

SciTech Connect (OSTI)

It has long been speculated that supernova remnants represent a major source of cosmic rays in the Galaxy. Observations over the past decade have ceremoniously unveiled direct evidence of particle acceleration in SNRs to energies approaching the knee of the cosmic ray spectrum. Nonthermal X-ray emission from shell-type SNRs reveals multi-TeV electrons, and the dynamical properties of several SNRs point to efficient acceleration of ions. Observations of TeV gamma-ray emission have confirmed the presence of energetic particles in several remnants as well, but there remains considerable debate as to whether this emission originates with high energy electrons or ions. Equally uncertain are the exact conditions that lead to efficient particle acceleration. Based on the catalog of EGRET sources, we know that there is a large population of Galactic gamma-ray sources whose distribution is similar to that of SNRs.With the increased resolution and sensitivity of GLAST, the gamma-ray SNRs from this population will be identified. Their detailed emission structure, along with their spectra, will provide the link between their environments and their spectra in other wavebands to constrain emission models and to potentially identify direct evidence of ion acceleration in SNRs. Here I summarize recent observational and theoretical work in the area of cosmic ray acceleration by SNRs, and discuss the contributions GLAST will bring to our understanding of this problem.

Slane, Patrick; /Harvard-Smithsonian Ctr. Astrophys.

2011-11-29T23:59:59.000Z

116

Lectures on Quantum Cosmology  

E-Print Network [OSTI]

The problems encountered in trying to quantize the various cosmological models, are brought forward by means of a concrete example. The Automorphism groups are revealed as the key element through which G.C.T.'s can be used for a general treatment of these problems. At the classical level, the time dependent automorphisms lead to significant simplifications of the line element for the generic spatially homogeneous geometry, without loss of generality. At the quantum level, the ''frozen'' automorphisms entail an important reduction of the configuration space --spanned by the 6 components of the scale factor matrix-- on which the Wheeler-DeWitt equation, is to be based. In this spirit the canonical quantization of the most general minisuperspace actions --i.e. with all six scale factor as well as the lapse function and the shift vector present-- describing the vacuum type II, I geometries, is considered. The reduction to the corresponding physical degrees of freedom is achieved through the usage of the linear constraints as well as the quantum version of the entire set of all classical integrals of motion.

T. Christodoulakis

2001-09-18T23:59:59.000Z

117

Density Perturbations for Running Cosmological Constant  

E-Print Network [OSTI]

The dynamics of density and metric perturbations is investigated for the previously developed model where the decay of the vacuum energy into matter (or vice versa) is due to the renormalization group (RG) running of the cosmological constant (CC) term. The evolution of the CC depends on the single parameter \

Julio C. Fabris; Ilya L. Shapiro; Joan Sola

2007-01-26T23:59:59.000Z

118

Observational Constraints on Cosmological Models with the Updated Long Gamma-Ray Bursts  

E-Print Network [OSTI]

In the present work, by the help of the newly released Union2 compilation which consists of 557 Type Ia supernovae (SNIa), we calibrate 109 long Gamma-Ray Bursts (GRBs) with the well-known Amati relation, using the cosmology-independent calibration method proposed by Liang {\\it et al.}. We have obtained 59 calibrated high-redshift GRBs which can be used to constrain cosmological models without the circularity problem (we call them ``Hymnium'' GRBs sample for convenience). Then, we consider the joint constraints on 7 cosmological models from the latest observational data, namely, the combination of 557 Union2 SNIa dataset, 59 calibrated Hymnium GRBs dataset (obtained in this work), the shift parameter $R$ from the WMAP 7-year data, and the distance parameter $A$ of the measurement of the baryon acoustic oscillation (BAO) peak in the distribution of SDSS luminous red galaxies. We also briefly consider the comparison of these 7 cosmological models.

Hao Wei

2010-08-16T23:59:59.000Z

119

Averaging Hypotheses in Newtonian Cosmology  

E-Print Network [OSTI]

Average properties of general inhomogeneous cosmological models are discussed in the Newtonian framework. It is shown under which circumstances the average flow reduces to a member of the standard Friedmann--Lema\\^\\i tre cosmologies. Possible choices of global boundary conditions of inhomogeneous cosmologies as well as consequences for the interpretation of cosmological parameters are put into perspective.

T. Buchert

1995-12-20T23:59:59.000Z

120

Testing the consistency between cosmological measurements of distance and age  

E-Print Network [OSTI]

We present a model independent method to test the consistency between cosmological measurements of distance and age, assuming the distance duality relation. We use type Ia supernovae, baryon acoustic oscillations, and observational Hubble data, to reconstruct the luminosity distance D_L(z), the angle averaged distance D_V(z) and the Hubble rate H(z), using Gaussian processes regression technique. We obtain estimate of the distance duality relation in the redshift range 0.1

Nair, Remya; Jain, Deepak

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Cosmological Parameters and the case for Cold Dark Matter  

E-Print Network [OSTI]

Determinations of the main cosmological parameters are reviewed and the implications for cold dark matter discussed. There is no longer an age problem for an $\\Omega_o = 1, \\Lambda = 0$ model and, if anything, there is now an age problem for low $\\Omega_o, \\Lambda > 0$ models. Large scale structure and CMB fluctuation data are best fitted by a mixed dark matter $\\Omega_o$ = 1 universe. Difficulties for this model with cluster evolution, the baryon content of clusters, high z Lyman $\\alpha$ galaxies, and the evidence from Type Ia supernovae favouring low $\\Omega_o, \\Lambda > 0$ models, are discussed critically.

M. Rowan-Robinson

1999-06-16T23:59:59.000Z

122

Workflow management for a cosmology collaboratory  

E-Print Network [OSTI]

nuclear processes in supernovae and to improve our abilityType Ia and Type II supernovae as reference light sources (with the goal of identifying supernovae in their earliest

Loken, Stewart C.; McParland, Charles

2001-01-01T23:59:59.000Z

123

Cosmology and New Physics  

E-Print Network [OSTI]

A comparison of the standard models in particle physics and in cosmology demonstrates that they are not compatible, though both are well established. Basics of modern cosmology are briefly reviewed. It is argued that the measurements of the main cosmological parameters are achieved through many independent physical phenomena and this minimizes possible interpretation errors. It is shown that astronomy demands new physics beyond the frameworks of the (minimal) standard model in particle physics. More revolutionary modifications of the basic principles of the theory are also discussed.

A. D. Dolgov

2006-06-21T23:59:59.000Z

124

Thermonuclear supernova simulations with stochastic ignition  

E-Print Network [OSTI]

We apply an ad hoc model for dynamical ignition in three-dimensional numerical simulations of thermonuclear supernovae assuming pure deflagrations. The model makes use of the statistical description of temperature fluctuations in the pre-supernova core proposed by Wunsch & Woosley (2004). Randomness in time is implemented by means of a Poisson process. We are able to vary the explosion energy and nucleosynthesis depending on the free parameter of the model which controls the rapidity of the ignition process. However, beyond a certain threshold, the strength of the explosion saturates and the outcome appears to be robust with respect to number of ignitions. In the most energetic explosions, we find about 0.75 solar masses of iron group elements. Other than in simulations with simultaneous multi-spot ignition, the amount of unburned carbon and oxygen at radial velocities of a few 1000 km/s tends to be reduced for an ever increasing number of ignition events and, accordingly, more pronounced layering results.

W. Schmidt; J. C. Niemeyer

2005-10-14T23:59:59.000Z

125

Transition redshift in $f(T)$ cosmology and observational constraints  

E-Print Network [OSTI]

We extract constraints on the transition redshift $z_{tr}$, determining the onset of cosmic acceleration, predicted by an effective cosmographic construction, in the framework of $f(T)$ gravity. In particular, employing cosmography we obtain bounds on the viable $f(T)$ forms and their derivatives. Since this procedure is model independent, as long as the scalar curvature is fixed, we are able to determine intervals for $z_{tr}$. In this way we guarantee that the Solar-System constraints are preserved and moreover we extract bounds on the transition time and the free parameters of the scenario. We find that the transition redshifts predicted by $f(T)$ cosmology, although compatible with the standard $\\Lambda$CDM predictions, are slightly smaller. Finally, in order to obtain observational constraints on $f(T)$ cosmology, we perform a Monte Carlo fitting using supernova data, involving the most recent union 2.1 data set.

Capozziello, Salvatore; Saridakis, Emmanuel N

2015-01-01T23:59:59.000Z

126

Reconstructing Dark Energy : A Comparison of Cosmological Parameters  

E-Print Network [OSTI]

A large number of cosmological parameters have been suggested for obtaining information on the nature of dark energy. In this work, we study the efficacy of these different parameters in discriminating theoretical models of dark energy, using both currently available supernova (SNe) data, and simulations of future observations. We find that the current data does not put strong constraints on the nature of dark energy, irrespective of the cosmological parameter used. For future data, we find that the although deceleration parameter can accurately reconstruct some dark energy models, it is unable to discriminate between different models of dark energy, therefore limiting its usefulness. Physical parameters such as the equation of state of dark energy, or the dark energy density do a good job of both reconstruction and discrimination if the matter density is known to high accuracy. However, uncertainty in matter density reduces the efficacy of these parameters. A recently proposed parameter, Om(z), constructed f...

Pan, Alexander V

2010-01-01T23:59:59.000Z

127

Spectropolarimetric diagnostics of thermonuclear supernova explosions  

E-Print Network [OSTI]

Even at extragalactic distances, the shape of supernova ejecta can be effectively diagnosed by spectropolarimetry. We present here results for 17 Type Ia supernovae that allow a statistical study of the correlation among the geometric structures and other observable parameters of Type Ia supernovae. These observations suggest that their ejecta typically consist of a smooth, central iron rich core and an outer layer with chemical asymmetries. The degree of this peripheral asphericity is correlated with the light-curve decline rate of Type Ia supernovae. These observations lend strong support to delayed-detonation models of Type Ia supernovae.

Lifan Wang; Dietrich Baade; Ferdinando Patat

2006-11-29T23:59:59.000Z

128

THE LOCAL HOSTS OF TYPE Ia SUPERNOVAE  

SciTech Connect (OSTI)

We use multi-wavelength, matched aperture, integrated photometry from the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey, and the RC3 to estimate the physical properties of 166 nearby galaxies hosting 168 well-observed Type Ia supernovae (SNe Ia). The ultraviolet (UV) imaging of local SN Ia hosts from GALEX allows a direct comparison with higher-redshift hosts measured at optical wavelengths that correspond to the rest-frame UV. Our data corroborate well-known features that have been seen in other SN Ia samples. Specifically, hosts with active star formation produce brighter and slower SNe Ia on average, and hosts with luminosity-weighted ages older than 1 Gyr produce on average more faint, fast, and fewer bright, slow SNe Ia than younger hosts. New results include that in our sample, the faintest and fastest SNe Ia occur only in galaxies exceeding a stellar mass threshold of approx10{sup 10} M{sub sun}, leading us to conclude that their progenitors must arise in populations that are older and/or more metal rich than the general SN Ia population. A low host extinction subsample hints at a residual trend in peak luminosity with host age, after correcting for light-curve shape, giving the appearance that older hosts produce less-extincted SNe Ia on average. This has implications for cosmological fitting of SNe Ia, and suggests that host age could be useful as a parameter in the fitting. Converting host mass to metallicity and computing {sup 56}Ni mass from the supernova light curves, we find that our local sample is consistent with a model that predicts a shallow trend between stellar metallicity and the {sup 56}Ni mass that powers the explosion, but we cannot rule out the absence of a trend. We measure a correlation between {sup 56}Ni mass and host age in the local universe that is shallower and not as significant as that seen at higher redshifts. The details of the age-{sup 56}Ni mass correlations at low and higher redshift imply a luminosity-weighted age threshold of approx3 Gyr for SN Ia hosts, above which they are less likely to produce SNe Ia with {sup 56}Ni masses above approx0.5 M{sub sun}.

Neill, James D.; Martin, D. Christopher; Barlow, Tom A.; Foster, Karl; Friedman, Peter G.; Morrissey, Patrick; Wyder, Ted K. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Sullivan, Mark [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Howell, D. Andrew [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States); Conley, Alex [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ONM5S3H8 (Canada); Seibert, Mark; Madore, Barry F. [The Observatories of the Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA, 91101 (United States); Neff, Susan G. [Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Schiminovich, David [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Bianchi, Luciana [Center for Astrophysical Sciences, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 (United States); Donas, Jose; Milliard, Bruno [Laboratoire d'Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12 (France); Heckman, Timothy M. [Department of Physics and Astronomy, Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Lee, Young-Wook [Center for Space Astrophysics, Yonsei University, Seoul 120-749 (Korea, Republic of); Rich, R. Michael [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

2009-12-20T23:59:59.000Z

129

Cosmological Ontology and Epistemology  

E-Print Network [OSTI]

In cosmology, we would like to explain our observations and predict future observations from theories of the entire universe. Such cosmological theories make ontological assumptions of what entities exist and what their properties and relationships are. One must also make epistemological assumptions or metatheories of how one can test cosmological theories. Here I shall propose a Bayesian analysis in which the likelihood of a complete theory is given by the normalized measure it assigns to the observation used to test the theory. In this context, a discussion is given of the trade-off between prior probabilities and likelihoods, of the measure problem of cosmology, of the death of Born's rule, of the Boltzmann brain problem, of whether there is a better principle for prior probabilities than mathematical simplicity, and of an Optimal Argument for the Existence of God.

Don N. Page

2014-12-23T23:59:59.000Z

130

Massive neutrinos and cosmology  

E-Print Network [OSTI]

The present experimental results on neutrino flavour oscillations provide evidence for non-zero neutrino masses, but give no hint on their absolute mass scale, which is the target of beta decay and neutrinoless double-beta decay experiments. Crucial complementary information on neutrino masses can be obtained from the analysis of data on cosmological observables, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure. In this review we describe in detail how free-streaming massive neutrinos affect the evolution of cosmological perturbations. We summarize the current bounds on the sum of neutrino masses that can be derived from various combinations of cosmological data, including the most recent analysis by the WMAP team. We also discuss how future cosmological experiments are expected to be sensitive to neutrino masses well into the sub-eV range.

Julien Lesgourgues; Sergio Pastor

2006-05-29T23:59:59.000Z

131

Dark gravity and cosmology  

E-Print Network [OSTI]

The previous version of this article was a first attempt to confront the Dark Gravity theory to cosmological data. However, more recent developments lead to the conclusion that the cosmological principle is probably not valid in Dark Gravity so that this kind of analysis is at best very premature. A more recent and living review of the Dark Gravity theory can be found in gr-qc/0610079

F. Henry-Couannier; A. Tilquin; C. Tao; A. Ealet

2007-10-24T23:59:59.000Z

132

What We Know About Dark Energy From Supernovae  

ScienceCinema (OSTI)

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.

Alex Filippenko

2010-01-08T23:59:59.000Z

133

Supernova neutrinos and explosive nucleosynthesis  

SciTech Connect (OSTI)

Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and ?{sub 13}, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements {sup 11}B and {sup 7}Li encapsulated in the presolar grains. Combining the recent experimental constraints on ?{sub 13}, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

Kajino, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Aoki, W. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Hayakawa, T. [Japan Atomic Energy Agency, Shirakara-Shirane 2-4, Tokai-mura, Ibaraki 319-1195 (Japan); Hidaka, J.; Hirai, Y.; Shibagaki, S. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Nakamura, K. [Faculty of Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Suzuki, T. [Department of Physics, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan)

2014-05-09T23:59:59.000Z

134

Determination of Primordial Metallicity and Mixing in the Type IIP Supernova 1993W  

SciTech Connect (OSTI)

We present the results of a large grid of synthetic spectra and compare them to early spectroscopic observations of SN 1993W. This supernova was discovered close to its explosion date and at a recession velocity of 5400 km/s is located in the Hubble flow. We focus here on two early spectra that were obtained approximately 5 and 9 days after explosion. We parameterize the outer supernova envelope as a power-law density profile in homologous expansion. In order to extract information on the value of the parameters a large number of models was required. We show that very early spectra combined with detailed models can provide constraints on the value of the power law index, the ratio of hydrogen to helium in the surface of the progenitor, the progenitor metallicity and the amount of radioactive nickel mixed into the outer envelope of the supernova. The spectral fits reproduce the observed spectra exceedingly well. The spectral results combined with the early photometry predict that the explosion date was 4.7 {+-} 0.7 days before the first spectrum was obtained. The ability to obtain the metallicity from early spectra make SN IIP attractive probes of chemical evolution in the universe and by showing that we have the ability to pin down the parameters of the progenitor and mixing during the supernova explosion, it is likely to make SN IIP useful cosmological distance indicators which are at the same time complementary to SNe Ia.

Baron, E.; Nugent, Peter E.; Branch, David; Hauschildt, Peter H.; Turatto, M.; Cappellaro, E.

2002-12-11T23:59:59.000Z

135

Could there be a hole in type Ia supernovae?  

E-Print Network [OSTI]

Highlight: The Physics of Supernovae. Pro- ceedings of the EThere Be A Hole In Type l a Supernovae? Daniel Kasen, Peterscenario, Type l a Supernovae (SNe la) arise from a white

Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

2004-01-01T23:59:59.000Z

136

The Photometric Properties of Nearby Type Ia Supernovae  

E-Print Network [OSTI]

The Rise-Time Distribution of Nearby Type Ia Supernovae 3.1Highlight: The Physics of Supernovae, ed. W. Hillebrandt &1.1 Supernovae . . . . . . . . . . . . . . 1.1.1

Ganeshalingam, Mohan

2012-01-01T23:59:59.000Z

137

Signatures of the Late Time Core-Collapse Supernova Environment  

E-Print Network [OSTI]

in K. Weiler (ed. ), Supernovae and Gamma-Ray Bursters, Vol.Recorded observations of supernovae go back almost twoModern observations of supernovae began in the late 1800s

Roberts, Luke Forrest

2012-01-01T23:59:59.000Z

138

Turbulence-Flame Interactions in Type Ia Supernovae  

E-Print Network [OSTI]

Interactions in Type Ia Supernovae A. J. Aspden 1 , J. B.involved in type Ia supernovae (SN Ia) requires the use of ?generated by RT in type Ia supernovae should obey Bolgiano-

Aspden, Andrew J; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (Authors 1, 2 & 3); Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (Author 4); Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (Author 5)

2008-01-01T23:59:59.000Z

139

Reducing Zero-point Systematics in Dark Energy Supernova Experiments  

E-Print Network [OSTI]

Schmidt, B . P. 2003, i n Supernovae a n d G a m m a - R a ynumber of observed supernovae, m a x i m u m surveyObservations of type l a Supernovae (SNe la) have allowed

Faccioli, Lorenzo

2011-01-01T23:59:59.000Z

140

An integral field spectrograph for SNAP supernova studies  

E-Print Network [OSTI]

identification of Type Ia supernovae and to standardize theof the mission. Keywords: SNAP, Supernovae, Integral field,measurement of some 2000 supernovae (SNe) of Type Ia up to a

2002-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Supernovae Spectra (La Jolla Institute, 1980)  

SciTech Connect (OSTI)

The workshop includes talks by invited speakers on observed supernova spectra, plasma conditions in supernova envelopes, on the present status and future requirements of atomic physics and spectroscopy that contribute to the solutions of the supernova problems. Of the 14 papers presented at the workshop, abstracts of two appeared previously in Energy Research Abstracts and abstracts of the remaining 12 were prepared separately for the data base. (GHT)

Meyerott, R.; Gillespie, G.H. (eds.)

1980-01-01T23:59:59.000Z

142

Massive Stars and their Supernovae  

E-Print Network [OSTI]

Massive stars and their supernovae are prominent sources of radioactive isotopes, the observations of which thus can help to improve our astrophysical models of those. Our understanding of stellar evolution and the final explosive endpoints such as supernovae or hypernovae or gamma-ray bursts relies on the combination of magneto-hydrodynamics, energy generation due to nuclear reactions accompanying composition changes, radiation transport, and thermodynamic properties (such as the equation of state of stellar matter). Nuclear energy production includes all nuclear reactions triggered during stellar evolution and explosive end stages, also among unstable isotopes produced on the way. Radiation transport covers atomic physics (e.g. opacities) for photon transport, but also nuclear physics and neutrino nucleon/nucleus interactions in late phases and core collapse. Here we want to focus on the astrophysical aspects, i.e. a description of the evolution of massive stars and their endpoints, with a special emphasis ...

Thielemann, Friedrich-Karl; Liebendörfer, Matthias; Diehl, Roland; 10.1007/978-3-642-12698-7_4

2010-01-01T23:59:59.000Z

143

Environmental impact of Supernova Remnants  

E-Print Network [OSTI]

The explosion of a supernovae (SN) represents the sudden injection of about 10^51 ergs of thermal and mechanical energy in a small region of space, causing the formation of powerful shock waves that propagate through the interstellar medium at speeds of several thousands of km/s. These waves sweep, compress and heat the interstellar material that they encounter, forming the supernova remnants. Their evolution over thousands of years change forever, irreversibly, not only the physical but also the chemical properties of a vast region of space that can span hundreds of parsecs. This contribution briefly analyzes the impact of these explosions, discussing the relevance of some phenomena usually associated with SNe and their remnants in the light of recent theoretical and observational results.

Dubner, Gloria

2015-01-01T23:59:59.000Z

144

The supernova that destroyed a galaxy  

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

scientists and collaborators capture in unprecedented detail extremely powerful supernovae explosions in the early universe and their effect on the nascent galaxies that gave...

145

Supernova Recognition using Support Vector Machines  

E-Print Network [OSTI]

tion Using Support Vector Machines and Neural Networks.using Support Vector Machines Raquel A. Romano Cecilia R.nding supernovae do not employ machine learning techniques.

Romano, Raquel A.; Aragon, Cecilia R.; Ding, Chris

2006-01-01T23:59:59.000Z

146

The late emission of thermonuclear supernovae  

E-Print Network [OSTI]

The subject of late-time emission of Type Ia supernovae and its implications for the understanding of the explosions of C+O WDs is reviewed.

Pilar Ruiz-Lapuente

1996-04-16T23:59:59.000Z

147

Exploring Systematic Effects in Thermonuclear Supernovae.  

E-Print Network [OSTI]

?? Type Ia supernovae (SNe) are bright astrophysical explosions that form a remarkably homogeneous class of objects serving as the premier distance indicators for studying… (more)

Jackson, Aaron Perry

2011-01-01T23:59:59.000Z

148

Turbulent Combustion in Type Ia Supernova Models  

E-Print Network [OSTI]

We review the astrophysical modeling of type Ia supernova explosions and describe numerical methods to implement numerical simulations of these events. Some results of such simulations are discussed.

F. K. Roepke; W. Hillebrandt

2006-09-15T23:59:59.000Z

149

A LUMINOUS AND FAST-EXPANDING TYPE Ib SUPERNOVA SN 2012au  

SciTech Connect (OSTI)

We present a set of photometric and spectroscopic observations of a bright Type Ib supernova SN 2012au from -6 days until {approx} + 150 days after maximum. The shape of its early R-band light curve is similar to that of an average Type Ib/c supernova. The peak absolute magnitude is M{sub R} = -18.7 {+-} 0.2 mag, which suggests that this supernova belongs to a very luminous group among Type Ib supernovae. The line velocity of He I {lambda}5876 is about 15,000 km s{sup -1} around maximum, which is much faster than that in a typical Type Ib supernova. From the quasi-bolometric peak luminosity of (6.7 {+-} 1.3) Multiplication-Sign 10{sup 42} erg s{sup -1}, we estimate the {sup 56}Ni mass produced during the explosion as {approx}0.30 M{sub Sun }. We also give a rough constraint to the ejecta mass 5-7 M{sub Sun} and the kinetic energy (7-18) Multiplication-Sign 10{sup 51} erg. We find a weak correlation between the peak absolute magnitude and He I velocity among Type Ib SNe. The similarities to SN 1998bw in the density structure inferred from the light-curve model as well as the large peak bolometric luminosity suggest that SN 2012au had properties similar to energetic Type Ic supernovae.

Takaki, Katsutoshi; Fukazawa, Yasushi; Itoh, Ryosuke; Ueno, Issei; Ui, Takahiro; Urano, Takeshi [Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Kawabata, Koji S.; Akitaya, Hiroshi; Moritani, Yuki; Ohsugi, Takashi; Uemura, Makoto; Yoshida, Michitoshi [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Yamanaka, Masayuki [Kwasan Observatory, Kyoto University, Ohmine-cho Kita Kazan, Yamashina-ku, Kyoto 607-8471 (Japan); Maeda, Keiichi; Nomoto, Ken'ichi [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Tanaka, Masaomi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Kinugasa, Kenzo [Nobeyama Radio Observatory, National Astronomical Observatory of Japan, 462-2 Nobeyama, Minamimaki, Nagano 384-1305 (Japan); Sasada, Mahito, E-mail: takaki@hep01.hepl.hiroshima-u.ac.jp [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)

2013-08-01T23:59:59.000Z

150

Testing the isotropy of the Universe by using the JLA compilation of type-Ia supernovae  

E-Print Network [OSTI]

We probe the possible anisotropy in the accelerated expanding Universe by using the JLA compilation of type-Ia supernovae. We constrain the amplitude and direction of anisotropy in the anisotropic cosmological models. For the dipole-modulated $\\Lambda$CDM model, the anisotropic amplitude has an upper bound $D<1.04\\times10^{-3}$ at the $68\\%$ confidence level. Similar results are found in the dipole-modulated $w$CDM and CPL models. Our studies show that there are no significant evidence for the anisotropic expansion of the Universe. Thus the Universe is still well compatible with the isotropy.

Lin, Hai-Nan; Chang, Zhe; Li, Xin

2015-01-01T23:59:59.000Z

151

Cosmology and the Bispectrum  

SciTech Connect (OSTI)

The present spatial distribution of galaxies in the Universe is non-Gaussian, with 40% skewness in 50 h{sup -1} Mpc spheres, and remarkably little is known about the information encoded in it about cosmological parameters beyond the power spectrum. In this work they present an attempt to bridge this gap by studying the bispectrum, paying particular attention to a joint analysis with the power spectrum and their combination with CMB data. They address the covariance properties of the power spectrum and bispectrum including the effects of beat coupling that lead to interesting cross-correlations, and discuss how baryon acoustic oscillations break degeneracies. They show that the bispectrum has significant information on cosmological parameters well beyond its power in constraining galaxy bias, and when combined with the power spectrum is more complementary than combining power spectra of different samples of galaxies, since non-Gaussianity provides a somewhat different direction in parameter space. In the framework of flat cosmological models they show that most of the improvement of adding bispectrum information corresponds to parameters related to the amplitude and effective spectral index of perturbations, which can be improved by almost a factor of two. Moreover, they demonstrate that the expected statistical uncertainties in {sigma}s of a few percent are robust to relaxing the dark energy beyond a cosmological constant.

Sefusatti, Emiliano; /Fermilab /CCPP, New York; Crocce, Martin; Pueblas, Sebastian; Scoccimarro, Roman; /CCPP, New York

2006-04-01T23:59:59.000Z

152

Nuclear physics and cosmology  

SciTech Connect (OSTI)

There are important aspects of Cosmology, the scientific study of the large scale properties of the universe as a whole, for which nuclear physics can provide insights. Here, we will focus on Standard Big-Bang Nucleosynthesis and we refer to the previous edition of the School [1] for the aspects concerning the variations of constants in nuclear cosmo-physics.

Coc, Alain [Centre de Sciences Nucléaires et de Sciences de la Matičre (CSNSM), CNRS/IN2P3, Université Paris Sud 11, UMR 8609, Bâtiment 104, F-91405 Orsay Campus (France)

2014-05-09T23:59:59.000Z

153

Relativistic Fractal Cosmologies  

E-Print Network [OSTI]

This article reviews an approach for constructing a simple relativistic fractal cosmology whose main aim is to model the observed inhomogeneities of the distribution of galaxies by means of the Lemaitre-Tolman solution of Einstein's field equations for spherically symmetric dust in comoving coordinates. This model is based on earlier works developed by L. Pietronero and J.R. Wertz on Newtonian cosmology, whose main points are discussed. Observational relations in this spacetime are presented, together with a strategy for finding numerical solutions which approximate an averaged and smoothed out single fractal structure in the past light cone. Such fractal solutions are shown, with one of them being in agreement with some basic observational constraints, including the decay of the average density with the distance as a power law (the de Vaucouleurs' density power law) and the fractal dimension in the range 1 fractal model we find that all Friedmann models look inhomogeneous along the backward null cone, with a departure from the observable homogeneous region at relatively close ranges. It is also shown that with these same observational relations the Einstein-de Sitter model can have an interpretation where it has zero global density, a result consistent with the "zero global density postulate" advanced by Wertz for hierarchical cosmologies and conjectured by Pietronero for fractal cosmological models. The article ends with a brief discussion on the possible link between this model and nonlinear and chaotic dynamics.

Marcelo B. Ribeiro

2009-10-26T23:59:59.000Z

154

Origin of Matter from Vacuum in Conformal Cosmology  

E-Print Network [OSTI]

We introduce the hypothesis that the matter content of the universe can be a product of the decay of primordial vector bosons. The effect of the intensive cosmological creation of these primordial vector $W, ~Z $ bosons from the vacuum is studied in the framework of General Relativity and the Standard Model where the relative standard of measurement identifying conformal quantities with the measurable ones is accepted. The relative standard leads to the conformal cosmology with the z-history of masses with the constant temperature, instead of the conventional z-history of the temperature with constant masses in inflationary cosmology. In conformal cosmology both the latest supernova data and primordial nucleosynthesis are compatible with a stiff equation of state associated with one of the possible states of the infrared gravitation field. The distribution function of the created bosons in the lowest order of perturbation theory exposes a cosmological singularity as a consequence of the theorem about the absence of the massless limit of massive vector fields in quantum theory. This singularity can be removed by taking into account the collision processes leading to a thermalization of the created particles. The cosmic microwave background (CMB) temperature T=(M_W^2H_0)^{1/3} ~ 2.7 K occurs as an integral of motion for the universe in the stiff state. We show that this temperature can be attained by the CMB radiation being the final product of the decay of primordial bosons. The effect of anomalous nonconservation of baryon number due to the polarization of the Dirac sea vacuum by these primordial bosons is considered.

D. Blaschke; V. Pervushin; D. Proskurin; S. Vinitsky; A. Gusev

2002-06-30T23:59:59.000Z

155

Cosmology with Coupled Gravity and Dark Energy  

E-Print Network [OSTI]

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

Ti-Pei Li

2015-01-13T23:59:59.000Z

156

Testing cosmology with cosmic sound waves  

SciTech Connect (OSTI)

Wilkinson Microwave Anisotropy Probe (WMAP) observations have accurately determined the position of the first two peaks and dips in the cosmic microwave background (CMB) temperature power spectrum. These encode information on the ratio of the distance to the last scattering surface to the sound horizon at decoupling. However prerecombination processes can contaminate this distance information. In order to assess the amplitude of these effects, we use the WMAP data and evaluate the relative differences of the CMB peak and dip multipoles. We find that the position of the first peak is largely displaced with respect to the expected position of the sound horizon scale at decoupling. In contrast, the relative spacings of the higher extrema are statistically consistent with those expected from perfect harmonic oscillations. This provides evidence for a scale dependent phase shift of the CMB oscillations which is caused by gravitational driving forces affecting the propagation of sound waves before recombination. By accounting for these effects we have performed a Markov Chain Monte Carlo likelihood analysis of the location of WMAP extrema to constrain, in combination with recent BAO data, a constant dark energy equation of state parameter w. For a flat universe we find a strong 2{sigma} upper limit w<-1.10, and including the Hubble Space Telescope prior, we obtain w<-1.14, which is only marginally consistent with limits derived from the Supernova Legacy Survey sample. On the other hand, we infer larger limits for nonflat cosmologies. From the full CMB likelihood analysis, we also estimate the values of the shift parameter R and the multipole l{sub a} of the acoustic horizon at decoupling for several cosmologies, to test their dependence on model assumptions. Although the analysis of the full CMB spectra should always be preferred, using the position of the CMB peaks and dips provides a simple and consistent method for combining CMB constraints with other data sets.

Corasaniti, Pier Stefano [LUTH, Observatoire de Paris, CNRS UMR 8102, Universite Paris Diderot, 5 Place Jules Janssen, 92195 Meudon Cedex (France); Melchiorri, Alessandro [Dipartimento di Fisica e Sezione INFN, Universita degli Studi di Roma 'La Sapienza', Ple Aldo Moro 5, 00185, Rome (Italy); CERN, Theory Division, CH-1211 Geneva 23 (Switzerland)

2008-05-15T23:59:59.000Z

157

Testing Cosmology with Cosmic Sound Waves  

E-Print Network [OSTI]

WMAP observations have accurately determined the position of the first two peaks and dips in the CMB temperature power spectrum. These encode information on the ratio of the distance to the last scattering surface to the sound horizon at decoupling. However pre-recombination processes can contaminate this distance information. In order to assess the amplitude of these effects we use the WMAP data and evaluate the relative differences of the CMB peaks and dips multipoles. We find that the position of the first peak is largely displaced with the respect to the expected position of the sound horizon scale at decoupling. In contrast the relative spacings of the higher extrema are statistically consistent with those expected from perfect harmonic oscillations. This provides evidence for a scale dependent phase shift of the CMB oscillations which is caused by gravitational driving forces affecting the propagation of sound waves before recombination. By accounting for these effects we have performed a MCMC likelihood analysis to constrain in combination with recent BAO data a constant dark energy equation w. For a flat universe we find at 95% upper limit w<-1.10, and including the HST prior w<-1.14, which are only marginally consistent with limits derived from the supernova SNLS sample. Larger limits are obtained for non-flat cosmologies. From the full CMB likelihood analysis we also estimate the values of the shift parameter R and the multipole l_a of the acoustic horizon at decoupling for several cosmologies to test their dependence on model assumptions. Although the analysis of the full CMB spectra should be always preferred, using the position of the CMB peaks and dips provide a simple and consistent method for combining CMB constraints with other datasets.

Pier Stefano Corasaniti; Alessandro Melchiorri

2008-03-25T23:59:59.000Z

158

Young Supernova Remnants: Issues and Prospects  

E-Print Network [OSTI]

After reviewing recent work on the dynamics of young supernova remnants (YSNRs) and discussing how YSNRs can be used as physics laboratories, I discuss several challenges: Where are the very young SNRs in the Galaxy? Can very young SNRs produce gamma ray bursts? The Connections Challenge: Can one infer the nature of the supernova and its progenitor star from observations of the YSNR?

Christopher F. McKee

2001-01-03T23:59:59.000Z

159

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

E-Print Network [OSTI]

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

Carl H. Gibson

2012-11-02T23:59:59.000Z

160

Petascale Supernova Simulation with CHIMERA  

SciTech Connect (OSTI)

CHIMERA is a multi-dimensional radiation hydrodynamics code designed to study core-collapse supernovae. The code is made up of three essentially independent parts: a hydrodynamics module, a nuclear burning module, and a neutrino transport solver combined within an operator-split approach. We describe some ma jor algorithmic facets of the code and briefly discuss some recent results. The multi-physics nature of the problem, and the specific implementation of that physics in CHIMERA, provide a rather straightforward path to effective use of multi-core platforms in the near future.

Messer, Bronson [ORNL; Bruenn, S. W. [Florida Atlantic University; Blondin, J. M. [North Carolina State University; Mezzacappa, Anthony [ORNL; Hix, William Raphael [ORNL; Dirk, Charlotte [Florida Atlantic University

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Supernova Caught in the Act  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassiveSubmittedStatus TomAbout »Lab (NewportSuccess StoriesNERSC @CenterSupernova

162

MOST POPULATION III SUPERNOVAE ARE DUDS Robert L. Kurucz  

E-Print Network [OSTI]

the ``dark matter'' halo. Subject headings: supernovae --- dark matter Introduction Most of the physics predictions about dud supernovae and about ``dark matter''. Population III stars, dud supernovae, supernovae and primordial gas into a globular cluster. Model atmosphere calculations for oxygen dwarfs show that water

Kurucz, Robert L.

163
164

Quantum cosmology: a review  

E-Print Network [OSTI]

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity: De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting "microscopic" degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.

Bojowald, Martin

2015-01-01T23:59:59.000Z

165

Holography from quantum cosmology  

E-Print Network [OSTI]

The Weyl-Wigner-Groenewold-Moyal formalism of deformation quantization is applied to the closed Friedmann-Lema\\^itre-Robertson-Walker (FLRW) cosmological model. We show that the phase space average for the surface of the apparent horizon is quantized in units of the Planck's surface, and that the total entropy of the universe is also quantized. Taking into account these two concepts, it is shown that 't Hooft conjecture on the cosmological holographic principle (CHP) in radiation and dust dominated quantum universes is satisfied as a manifestation of quantization. This suggests that the entire universe (not only inside the apparent horizon) can be seen as a two-dimensional information structure encoded on the apparent horizon.

M. Rashki; S. Jalalzadeh

2014-12-12T23:59:59.000Z

166

Quantum cosmology: a review  

E-Print Network [OSTI]

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity: De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting "microscopic" degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.

Martin Bojowald

2015-01-20T23:59:59.000Z

167

Cosmology with running parameters  

E-Print Network [OSTI]

The experimental evidence that the equation of state (EOS) of the dark energy (DE) could be evolving with time/redshift (including the possibility that it might behave phantom-like near our time) suggests that there might be dynamical DE fields that could explain this behavior. We propose, instead, that a variable cosmological term (including perhaps a variable Newton's gravitational coupling too) may account in a natural way for all these features.

Joan Sola

2005-12-05T23:59:59.000Z

168

Standard cosmology delayed  

SciTech Connect (OSTI)

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

Choudhury, Debajyoti [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Ghoshal, Debashis [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Sen, Anjan Ananda, E-mail: debajyoti.choudhury@gmail.com, E-mail: dghoshal@mail.jnu.ac.in, E-mail: anjan.ctp@jmi.ac.in [Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi 110025 (India)

2012-02-01T23:59:59.000Z

169

Standard Cosmology Delayed  

E-Print Network [OSTI]

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

Debajyoti Choudhury; Debashis Ghoshal; Anjan Ananda Sen

2012-02-06T23:59:59.000Z

170

Standard Cosmology Delayed  

E-Print Network [OSTI]

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

Choudhury, Debajyoti; Sen, Anjan Ananda

2011-01-01T23:59:59.000Z

171

Cosmological shock waves  

E-Print Network [OSTI]

Large-scale structure formation, accretion and merging processes, AGN activity produce cosmological gas shocks. The shocks convert a fraction of the energy of gravitationally accelerated flows to internal energy of the gas. Being the main gas-heating agent, cosmological shocks could amplify magnetic fields and accelerate energetic particles via the multi-fluid plasma relaxation processes. We first discuss the basic properties of standard single-fluid shocks. Cosmological plasma shocks are expected to be collisionless. We then review the plasma processes responsible for the microscopic structure of collisionless shocks. A tiny fraction of the particles crossing the shock is injected into the non-thermal energetic component that could get a substantial part of the ram pressure power dissipated at the shock. The energetic particles penetrate deep into the shock upstream producing an extended shock precursor. Scaling relations for postshock ion temperature and entropy as functions of shock velocity in strong collisionless multi-fluid shocks are discussed. We show that the multi-fluid nature of collisionless shocks results in excessive gas compression, energetic particle acceleration, precursor gas heating, magnetic field amplification and non-thermal emission. Multi-fluid shocks provide a reduced gas entropy production and could also modify the observable thermodynamic scaling relations for clusters of galaxies.

A. M. Bykov; K. Dolag; F. Durret

2008-01-07T23:59:59.000Z

172

Particle Physics and Cosmology  

E-Print Network [OSTI]

Today, both particle physics and cosmology are described by few parameter Standard Models, i.e. it is possible to deduce consequence of particle physics in cosmology and vice verse. The former is examined in this lecture, in light of the recent systematic exploration of the electroweak scale by the LHC experiments. The two main results of the first phase of the LHC, the discovery of a Higgs-like particle and the absence so far of new particles predicted by "natural" theories beyond the Standard Model (supersymmetry, extra-dimension and composite Higgs) are put in a historical context to enlighten their importance and then presented extensively. To be complete, a short review from the neutrino physics, which can not be probed at LHC, is also given. The ability of all these results to resolve the 3 fundamental questions of cosmology about the nature of dark energy and dark matter as well as the origin of matter-antimatter asymmetry is discussed in each case.

P. Pralavorio

2014-12-04T23:59:59.000Z

173

Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution  

E-Print Network [OSTI]

Number Modeling of Type Ia Supernovae. II. Energy EvolutionIa. Subject headings: supernovae: general — white dwarfs —the ignition of Type Ia supernovae (SNe Ia) is critical to

Almgren, Ann S.; Bell, John B.; Rendleman, Charles A.; Zingale, Mike

2006-01-01T23:59:59.000Z

174

Direct numerical simulations of type Ia supernovae flames I: The landau-darrieus instability  

E-Print Network [OSTI]

Simulations of Type Ia Supernovae Flames I: The Landau-Subject headings: supernovae: general — white dwarfs —could occur in Type Ia supernovae (Niemeyer & Woosley 1997),

Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

2003-01-01T23:59:59.000Z

175

Direct numerical simulations of type Ia supernovae flames II: The rayleigh-taylor instability  

E-Print Network [OSTI]

Weaver, T. A. 1994, in Supernovae, Les Houches, Session LIV,Simulations of Type Ia Supernovae Flames II: The Rayleigh-Subject headings: supernovae: general — white dwarfs —

Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

2004-01-01T23:59:59.000Z

176

A complete analytic inversion of supernova lines in the Sobolev approximation  

E-Print Network [OSTI]

D . & Branch, D . 1990, in Supernovae, ed. J . C . Wheeler &radia­ tive transfer — supernovae Lawrence Berkeley Nationalgradients, such as supernovae. The Sobolev approximation has

Kasen, Daniel; Branch, David; Baron, E.; Jeffery, David

2001-01-01T23:59:59.000Z

177

Spectral Observations and Analyses of Low-Redshift Type Ia Supernovae  

E-Print Network [OSTI]

1.2 Why Study Supernovae? . . . . . . . . . . . . .1.3 What are Supernovae? . . . . . . . .Core-Collapse Supernovae . . . . . . . . 1.3.2 Thermonuclear

Silverman, Jeffrey Michael

2011-01-01T23:59:59.000Z

178

Progress Report on the Berkeley/Anglo-Australian Observatory High-Redshift Supernova Search  

E-Print Network [OSTI]

photometry curve for type Ia supernovae and the redshift vsdistributions for observed supernovae. Figure 5 from Millermain efforts related to supernovae in progress at Berkeley.

Goldhaber, G.

2008-01-01T23:59:59.000Z

179

High-Redshift Type Ia Supernova Rates in Galaxy Cluster and Field Environments  

E-Print Network [OSTI]

29 Candidates classified as supernovae . . . . . . . .1.1 Type Ia Supernovae as Standard Candles . . . . . . . .4.2.3 Supernovae . . . . . . . . . . . . . . . . 4.2.4

Barbary, Kyle Harris

2011-01-01T23:59:59.000Z

180

Long gamma-ray bursts and core-collapse supernovae have different environments  

E-Print Network [OSTI]

and core-collapse supernovae have dif- ferent environmentsObservational Evidence from Supernovae for an Acceleratingfrom 42 High-Redshift Supernovae. Astrophys. J. 517, 565–

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

How to Find More Supernovae with Less Work: Object Classification Techniques for Difference Imaging  

E-Print Network [OSTI]

How to Find More Supernovae with Less Work: Object Classi?methods: statistical — supernovae: general — techniques:for objects such as supernovae, active galactic nuclei,

Bailey, Stephen; Aragon, Cecilia; Romano, Raquel; Thomas, Rollin C.; Weaver, Benjamin A.; Wong, Daniel

2007-01-01T23:59:59.000Z

182

E-Print Network 3.0 - atypical thermonuclear supernovae Sample...  

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

thermonuclear supernovae Search Powered by Explorit Topic List Advanced Search Sample search results for: atypical thermonuclear supernovae Page: << < 1 2 3 4 5 > >> 1 Supernova...

183

Cosmology for high energy physicists  

SciTech Connect (OSTI)

The standard big bang model of cosmology is presented. Although not perfect, its many successes make it a good starting point for most discussions of cosmology. Places are indicated where well understood laboratory physics is incorporated into the big bang, leading to successful predictions. Much less established aspects of high energy physics and some of the new ideas they have introduced into the field of cosmology are discussed, such as string theory, inflation and monopoles. 49 refs., 5 figs.

Albrecht, A.

1987-11-01T23:59:59.000Z

184

Detonating Failed Deflagration Model of Thermonuclear Supernovae I. Explosion Dynamics  

E-Print Network [OSTI]

We present a detonating failed deflagration model of Type Ia supernovae. In this model, the thermonuclear explosion of a massive white dwarf follows an off-center deflagration. We conduct a survey of asymmetric ignition configurations initiated at various distances from the stellar center. In all cases studied, we find that only a small amount of stellar fuel is consumed during deflagration phase, no explosion is obtained, and the released energy is mostly wasted on expanding the progenitor. Products of the failed deflagration quickly reach the stellar surface, polluting and strongly disturbing it. These disturbances eventually evolve into small and isolated shock-dominated regions which are rich in fuel. We consider these regions as seeds capable of forming self-sustained detonations that, ultimately, result in the thermonuclear supernova explosion. Preliminary nucleosynthesis results indicate the model supernova ejecta are typically composed of about 0.1-0.25 Msun of silicon group elements, 0.9-1.2 Msun of iron group elements, and are essentially carbon-free. The ejecta have a composite morphology, are chemically stratified, and display a modest amount of intrinsic asymmetry. The innermost layers are slightly egg-shaped with the axis ratio ~1.2-1.3 and dominated by the products of silicon burning. This central region is surrounded by a shell of silicon-group elements. The outermost layers of ejecta are highly inhomogeneous and contain products of incomplete oxygen burning with only small admixture of unburned stellar material. The explosion energies are ~1.3-1.5 10^51 erg.

Tomasz Plewa

2006-11-24T23:59:59.000Z

185

Theoretical cosmic Type Ia supernova rates  

E-Print Network [OSTI]

The aim of this work is the computation of the cosmic Type Ia supernova rates at very high redshifts (z>2). We adopt various progenitor models in order to predict the number of explosions in different scenarios for galaxy formation and to check whether it is possible to select the best delay time distribution model, on the basis of the available observations of Type Ia supernovae. We also computed the Type Ia supernova rate in typical elliptical galaxies of different initial luminous masses and the total amount of iron produced by Type Ia supernovae in each case. It emerges that: it is not easy to select the best delay time distribution scenario from the observational data and this is because the cosmic star formation rate dominates over the distribution function of the delay times; the monolithic collapse scenario predicts an increasing trend of the SN Ia rate at high redshifts whereas the predicted rate in the hierarchical scheme drops dramatically at high redshift; for the elliptical galaxies we note that the predicted maximum of the Type Ia supernova rate depends on the initial galactic mass. The maximum occurs earlier (at about 0.3 Gyr) in the most massive ellipticals, as a consequence of downsizing in star formation. We find that different delay time distributions predict different relations between the Type Ia supernova rate per unit mass at the present time and the color of the parent galaxies and that bluer ellipticals present higher supernova Type Ia rates at the present time.

R. Valiante; F. Matteucci; S. Recchi; F. Calura

2009-03-16T23:59:59.000Z

186

Inference for the dark energy equation of state using Type IA supernova data  

E-Print Network [OSTI]

The surprising discovery of an accelerating universe led cosmologists to posit the existence of "dark energy"--a mysterious energy field that permeates the universe. Understanding dark energy has become the central problem of modern cosmology. After describing the scientific background in depth, we formulate the task as a nonlinear inverse problem that expresses the comoving distance function in terms of the dark-energy equation of state. We present two classes of methods for making sharp statistical inferences about the equation of state from observations of Type Ia Supernovae (SNe). First, we derive a technique for testing hypotheses about the equation of state that requires no assumptions about its form and can distinguish among competing theories. Second, we present a framework for computing parametric and nonparametric estimators of the equation of state, with an associated assessment of uncertainty. Using our approach, we evaluate the strength of statistical evidence for various competing models of dark energy. Consistent with current studies, we find that with the available Type Ia SNe data, it is not possible to distinguish statistically among popular dark-energy models, and that, in particular, there is no support in the data for rejecting a cosmological constant. With much more supernova data likely to be available in coming years (e.g., from the DOE/NASA Joint Dark Energy Mission), we address the more interesting question of whether future data sets will have sufficient resolution to distinguish among competing theories.

Christopher Genovese; Peter Freeman; Larry Wasserman; Robert Nichol; Christopher Miller

2009-05-18T23:59:59.000Z

187

Uncorrelated Measurements of the Cosmic Expansion History and Dark Energy from Supernovae  

E-Print Network [OSTI]

We present a method for measuring the cosmic expansion history H(z) in uncorrelated redshift bins, and apply it to current and simulated type Ia supernova data assuming spatial flatness. If the matter density parameter Omega_m can be accurately measured from other data, then the dark energy density history X(z)=rho_X(z)/rho_X(0) can trivially be derived from this expansion history H(z). In contrast to customary ``black box'' parameter fitting, our method is transparent and easy to interpret: the measurement of H(z)^{-1} in a redshift bin is simply a linear combination of the measured comoving distances for supernovae in that bin, making it obvious how systematic errors propagate from input to output. We find the Riess et al. (2004) ``gold'' sample to be consistent with the ``vanilla'' concordance model where the dark energy is a cosmological constant. We compare two mission concepts for the NASA/DOE Joint Dark Energy Mission (JDEM), the Joint Efficient Dark-energy Investigation (JEDI), and the Supernova Accelaration Probe (SNAP), using simulated data including the effect of weak lensing (based on numerical simulations) and a systematic bias from K-corrections. Estimating H(z) in seven uncorrelated redshift bins, we find that both provide dramatic improvements over current data: JEDI can measure H(z) to about 10% accuracy and SNAP to 30-40% accuracy.

Yun Wang; Max Tegmark

2005-05-13T23:59:59.000Z

188

Tycho Brahe's 1572 supernova as a standard type Ia explosion revealed from its light echo spectrum  

E-Print Network [OSTI]

Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions are how the explosion actually proceeds and whether accretion occurs from a companion or via the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a SN Ia in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the yet unknown exact spectroscopic type of SN 1572 is crucial to relate these results to the diverse population of SNe Ia. Here we report an optical spectrum of Tycho Brahe's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light of the explosion swept past Earth. We find that SN 1572 belongs to the majority class of normal SNe Ia. The presence of a strong Ca II IR feature at velocities exceeding 20,000 km/s, which is similar to the previously observed polarized features in other SNe Ia, suggests asphericity in SN 1572.

Oliver Krause; Masaomi Tanaka; Tomonori Usuda; Takashi Hattori; Miwa Goto; Stephan Birkmann; Ken'ichi Nomoto

2008-10-28T23:59:59.000Z

189

Tycho Brahe's 1572 supernova as a standard type Ia explosion revealed from its light echo spectrum  

E-Print Network [OSTI]

Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions are how the explosion actually proceeds and whether accretion occurs from a companion or via the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a SN Ia in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the yet unknown exact spectroscopic type of SN 1572 is crucial to relate these results to the diverse population of SNe Ia. Here we report an optical spectrum of Tycho Brahe's supernova near maximum brightness, obtained from a scatter...

Krause, Oliver; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Birkmann, Stephan; Nomoto, Ken'ichi

2008-01-01T23:59:59.000Z

190

SPECTROSCOPY OF TYPE Ia SUPERNOVAE BY THE CARNEGIE SUPERNOVA PROJECT  

SciTech Connect (OSTI)

This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of Almost-Equal-To 0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a Almost-Equal-To 2{sigma}-3{sigma} correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.

Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, 277-8583 Kashiwa (Japan); Morrell, Nidia; Phillips, Mark M.; Hsiao, Eric; Campillay, Abdo; Contreras, Carlos; Castellon, Sergio; Roth, Miguel [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Hamuy, Mario; Anderson, Joseph P. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Krzeminski, Wojtek [N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa (Poland); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Burns, Christopher R.; Freedman, Wendy L.; Madore, Barry F.; Murphy, David; Persson, S. E. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Prieto, Jose L. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Ln., Princeton, NJ 08544 (United States); Suntzeff, Nicholas B.; Krisciunas, Kevin, E-mail: gaston.folatelli@ipmu.jp [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); and others

2013-08-10T23:59:59.000Z

191

Cosmological solutions in bimetric gravity and their observational tests  

SciTech Connect (OSTI)

We obtain the general cosmological evolution equations for a classically consistent theory of bimetric gravity. Their analytic solutions are demonstrated to generically allow for a cosmic evolution starting out from a matter dominated FLRW universe and relaxing towards a de Sitter (anti-de Sitter) phase at late cosmic time. In particular, we examine a subclass of models which contain solutions that are able to reproduce the expansion history of the cosmic concordance model inspite of the nonlinear couplings of the two metrics. This is demonstrated explicitly by fitting these models to observational data from Type Ia supernovae, Cosmic Microwave Background and Baryon Acoustic Oscillations. In the appendix we comment on the relation to massive gravity.

Strauss, Mikael von; Schmidt-May, Angnis; Enander, Jonas; Mörtsell, Edvard; Hassan, S.F., E-mail: mvs@fysik.su.se, E-mail: angnis.schmidt-may@fysik.su.se, E-mail: enander@fysik.su.se, E-mail: edvard@fysik.su.se, E-mail: fawad@fysik.su.se [Department of Physics and The Oskar Klein Centre for Cosmoparticle Physics, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden)

2012-03-01T23:59:59.000Z

192

Archeops: an instrument for present and future cosmology  

E-Print Network [OSTI]

Archeops is a balloon-borne instrument dedicated to measure the cosmic microwave background (CMB) temperature anisotropies. It has, in the millimetre domain (from 143 to 545 GHz), a high angular resolution (about 10 arcminutes) in order to constrain high l multipoles, as well as a large sky coverage fraction (30%) in order to minimize the cosmic variance. It has linked, before WMAP, Cobe large angular scales to the first acoustic peak region. From its results, inflation motivated cosmologies are reinforced with a flat Universe (Omega_tot=1 within 3%). The dark energy density and the baryonic density are in very good agreement with other independent estimations based on supernovae measurements and big bang nucleosynthesis. Important results on galactic dust emission polarization and their implications for Planck are also addressed.

M. Tristram

2003-09-12T23:59:59.000Z

193

String Landscape and Supernovae Ia  

E-Print Network [OSTI]

We present a model for the triggering of Supernovae Ia (SN Ia) by a phase transition to exact supersymmetry (susy) in the core of a white dwarf star. The model, which accomodates the data on SN Ia and avoids the problems of the standard astrophysical accretion based picture, is based on string landscape ideas and assumes that the decay of the false broken susy vacuum is enhanced at high density. In a slowly expanding susy bubble, the conversion of pairs of fermions to pairs of degenerate scalars releases a significant amount of energy which induces fusion in the surrounding normal matter shell. After cooling, the absence of degeneracy pressure causes the susy bubble to collapse to a black hole of about 0.1 solar mass or to some other stable susy object.

L. Clavelli

2011-10-09T23:59:59.000Z

194

Hydrogen in Type Ic Supernovae?  

E-Print Network [OSTI]

By definition, a Type Ic supernova (SN Ic) does not have conspicuous lines of hydrogen or helium in its optical spectrum. SNe Ic usually are modelled in terms of the gravitational collapse of bare carbon-oxygen cores. We consider the possibility that the spectra of ordinary (SN 1994I-like) SNe Ic have been misinterpreted, and that SNe Ic eject hydrogen. An absorption feature usually attributed to a blend of Si II 6355 and C II 6580 may be produced by H-alpha. If SN 1994I-like SNe Ic eject hydrogen, the possibility that hypernova (SN 1998bw-like) SNe Ic, some of which are associated with gamma-ray bursts, also eject hydrogen should be considered. The implications of hydrogen for SN Ic progenitors and explosion models are briefly discussed.

David Branch; David J. Jeffery; Timothy R. Young; E. Baron

2006-05-09T23:59:59.000Z

195

Cosmological models with isotropic singularities  

E-Print Network [OSTI]

In 1985 Goode and Wainwright devised the concept of an isotropic singularity. Since that time, numerous authors have explored the interesting consequences, in mathematical cosmology, of assuming the existence of this type of singularity. In this paper, we collate all examples of cosmological models which are known to admit an isotropic singularity, and make a number of observations regarding their general characteristics.

Susan M. Scott; Geoffery Ericksson

1998-12-07T23:59:59.000Z

196

Supercomputing and the search for supernovae  

SciTech Connect (OSTI)

Berkeley Lab's Peter Nugent discusses "Supercomputing and the search for supernovae" in this Oct. 28, 2013 talk, which is part of a Science at the Theater event entitled Eight Big Ideas.

Nugent, Peter

2013-10-31T23:59:59.000Z

197

Supercomputing and the search for supernovae  

ScienceCinema (OSTI)

Berkeley Lab's Peter Nugent discusses "Supercomputing and the search for supernovae" in this Oct. 28, 2013 talk, which is part of a Science at the Theater event entitled Eight Big Ideas.

Nugent, Peter

2014-06-23T23:59:59.000Z

198

UV Light Curves of Thermonuclear Supernovae  

E-Print Network [OSTI]

Ultraviolet light curves are calculated for several thermonuclear supernova models using a multifrequency radiation hydrodynamic code. It is found that Chandrasekhar-mass models produce very similar light curves both for detonation and deflagration. Sub-Chandrasekhar-mass models essentially differ from ``normal'' Chandrasekhar ones regarding behaviour of their UV fluxes. Differences in absolute brightness and in shape of light curves of thermonuclear supernovae could be detectable up to 300 Mpc with modern UV space telescopes.

S. I. Blinnikov; E. I. Sorokina

2000-03-17T23:59:59.000Z

199

Supernova/Acceleration Probe: A Satellite Experiment to Study the Nature of the Dark Energy  

SciTech Connect (OSTI)

The Supernova/Acceleration Probe (SNAP) is a proposed space-based experiment designed to study the dark energy and alternative explanations of the acceleration of the Universes expansion by performing a series of complementary systematics-controlled astrophysical measurements. We here describe a self-consistent reference mission design that can accomplish this goal with the two leading measurement approaches being the Type Ia supernova Hubble diagram and a wide-area weak gravitational lensing survey. This design has been optimized to first order and is now under study for further modification and optimization. A 2-m three-mirror anastigmat wide-field telescope feeds a focal plane consisting of a 0.7 square-degree imager tiled with equal areas of optical CCDs and near infrared sensors, and a high efficiency low-resolution integral field spectrograph. The instrumentation suite provides simultaneous discovery and light-curve measurements of supernovae and then can target individual objects for detailed spectral characterization. The SNAP mission will discover thousands of Type Ia supernovae out to z = 3 and will obtain high-signal-to-noise calibrated light-curves and spectra for a subset of > 2000 supernovae at redshifts between z = 0.1 and 1.7 in a northern field and in a southern field. A wide-field survey covering one thousand square degrees in both northern and southern fields resolves {approx} 100 galaxies per square arcminute, or a total of more than 300 million galaxies. With the PSF stability afforded by a space observatory, SNAP will provide precise and accurate measurements of gravitational lensing. The high-quality data available in space, combined with the large sample of supernovae, will enable stringent control of systematic uncertainties. The resulting data set will be used to determine the energy density of dark energy and parameters that describe its dynamical behavior. The data also provide a direct test of theoretical models for the dark energy, including discrimination of vacuum energy due to the cosmological constant and various classes of dynamical scalar fields. If we assume we live in a cosmological-constant-dominated Universe, the matter density, dark energy density, and flatness of space can all be measured with SNAP supernova and weak-lensing measurements to a systematics-limited accuracy of 1 percent. For a flat universe, the density-to-pressure ratio of dark energy or equation of state w(z) can be similarly measured to 5 percent for the present value w0 and {approx} 0.1 for the time variation w' is defined as dw/d ln a bar z = 1. For a fiducial SUGRA-inspired universe, w0 and w' can be measured to an even tighter uncertainty of 0.03 and 0.06 respectively. Note that no external priors are needed. As more accurate theoretical predictions for the small-scale weak-lensing shear develop, the conservative estimates adopted here for space-based systematics should improve, allowing even tighter constraints. While the survey strategy is tailored for supernova and weak gravitational lensing observations, the large survey area, depth, spatial resolution, time-sampling, and nine-band optical to NIR photometry will support additional independent and/or complementary dark-energy measurement approaches as well as a broad range of auxiliary science programs.

Aldering, G.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Baltay, C.; Barrelet, E.; Basa, E.; Bebek, C.; Bergstrom, L.; Bernstein, G.; Bester, M.; Bigelow, C.; Blandford, R.; Bohlin, R.; Bonissent, A.; Bower, C.; Brown, M.; Campbell, M.; Carithers, W.; Commins, E.; Craig, W.; Day, C.; DeJongh, F.; Deustua, S.; Diehl, T.; Dodelson, S.; Ealet, A.; Ellis, R.; Emmet, W.; Fouchez, D.; Frieman, J.; Fruchter, A.; Gerdes, D.; Gladney, L.; Goldhaber, G.; Goobar, A.; Groom, D.; Heetderks, H.; Hoff, M.; Holland, S.; Huffer, M.; Hui, L.; Huterer, D.; Jain, B.; Jelinsky, P.; Karcher, A.; Kent, S.; Kahn, S.; Kim, A.; Kolbe, W.; Krieger, B.; Kushner, G.; Kuznetsova, N.; Lafever, R.; Lamoureux, J.; Lampton, M.; Le Fevre, O.; Levi, M.; Limon, P.; Lin, H.; Linder, E.; Loken, S.; Lorenzon, W.; Malina, R.; Marriner, J.; Marshall, P.; Massey, R.; Mazure, A.; McKay, T.; McKee, S.; Miquel, R.; Morgan, N.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Nugent, P.; Oluseyi, H.; Pain, R.; Palaio, N.; Pankow, D.; Peoples, J.; Perlmutter, S.; Prieto, E.; Rabinowitz, D.; Refregier, A.; Rhodes, J.; Roe, N.; Rusin, D.; Scarpine, V.; Schubnell, M.; Sholl, M.; Samdja, G.; Smith, R.M.; Smoot, G.; Snyder, J.; Spadafora, A.; Stebbine, A.; Stoughton, C.; Szymkowiak, A.; Tarle, G.; Taylor, K.; Tilquin, A.; Tomasch, A.; Tucker, D.; Vincent, D.; von der Lippe, H.; Walder, J-P.; Wang, G.; Wester, W.

2004-05-12T23:59:59.000Z

200

The Standard Cosmological Model  

E-Print Network [OSTI]

The Standard Model of Particle Physics (SMPP) is an enormously successful description of high energy physics, driving ever more precise measurements to find "physics beyond the standard model", as well as providing motivation for developing more fundamental ideas that might explain the values of its parameters. Simultaneously, a description of the entire 3-dimensional structure of the present-day Universe is being built up painstakingly. Most of the structure is stochastic in nature, being merely the result of the particular realisation of the "initial conditions" within our observable Universe patch. However, governing this structure is the Standard Model of Cosmology (SMC), which appears to require only about a dozen parameters. Cosmologists are now determining the values of these quantities with increasing precision in order to search for "physics beyond the standard model", as well as trying to develop an understanding of the more fundamental ideas which might explain the values of its parameters. Although it is natural to see analogies between the two Standard Models, some intrinsic differences also exist, which are discussed here. Nevertheless, a truly fundamental theory will have to explain both the SMPP and SMC, and this must include an appreciation of which elements are deterministic and which are accidental. Considering different levels of stochasticity within cosmology may make it easier to accept that physical parameters in general might have a non-deterministic aspect.

Douglas Scott

2005-10-26T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Cosmology with decaying particles  

SciTech Connect (OSTI)

We consider a cosmological model in which an unstable massive relic particle species (denoted by X) has an initial mass density relative to baryons ..beta../sup -1/ identically equal rho/sub X//rho/sub B/ >> 1, and then decays recently (redshift z less than or equal to 1000) into particles which are still relativistic today (denoted by R). We write down and solve the coupled equations for the cosmic scale factor a(t), the energy density in the various components (rho/sub X/, rho/sub R/, rho/sub B/), and the growth of linear density perturbations (delta rho/rho). The solutions form a one parameter (..beta..) family of solutions; physically ..beta../sup -1/ approx. = (..cap omega../sub R//..cap omega../sub NR/) x (1 + z/sub D/) = (ratio today of energy density of relativistic to nonrelativistic particles) x (1 + redshift of (decay)). We discuss the observational implications of such a cosmological model and compare our results to earlier results computed in the simultaneous decay approximation. In an appendix we briefly consider the case where one of the decay products of the X is massive and becomes nonrelativistic by the present epoch. 21 references.

Turner, M.S.

1984-09-01T23:59:59.000Z

202

White dwarf mergers,White dwarf mergers, thermonuclear supernovae,thermonuclear supernovae,  

E-Print Network [OSTI]

White dwarf mergers,White dwarf mergers, thermonuclear supernovae,thermonuclear supernovae fusion is ignited. Degenerate, hence runaway. #12;CO white dwarf accretes, either from companion, or from disk after merger. As it approaches maximum mass, C fusion is ignited. Degenerate, hence runaway. SN Ia

Hinton, Jim

203

Theoretical Clues to the Ultraviolet Diversity of Type Ia Supernovae  

E-Print Network [OSTI]

The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, ^56 Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of t...

Brown, Peter J; Milne, Peter; Roming, Peter W A; Wang, Lifan

2015-01-01T23:59:59.000Z

204

The magnification of SN 1997ff, the farthest known supernova  

SciTech Connect (OSTI)

With a redshift of z {approx} 1.7, SN 1997ff is the most distant type Ia supernova discovered so far. This SN is close to several bright, z = 0.6-0.9 galaxies, and we consider the effects of lensing by those objects on the magnitude of SN 1997ff. We estimate their velocity dispersions using the Tully-Fisher and Faber-Jackson relations corrected for evolution effects, and calculate, applying the multiple-plane lensing formalism, that SN 1997ff is magnified by 0.34{+-}0.12 mag. Due to the spatial configuration of the foreground galaxies, the shear from individual lenses partially cancels out,and the total distortion induced on the host galaxy is considerably smaller than that produced by a single lens having the same magnification. After correction for lensing, the revised distance to SN 1997ff is m-M = 45.49 {+-} 0.34 mag, which improves the agreement with the {Omega}{sub M} = 0.35, {Omega}{Lambda} = 0.65 cosmology expected from lower-redshift SNe Ia, and is inconsistent at the {approx} 3 sigma confidence level with a uniform gray dust model or a simple evolution model.

Benitez, Narciso; Riess, Adam; Nugent, Peter; Dickinson, Mark; Chornock, Ryan; Filippenko, Alexei V.

2002-09-03T23:59:59.000Z

205

Cosmological perturbations on local systems  

E-Print Network [OSTI]

We study the effect of cosmological expansion on orbits--galactic, planetary, or atomic--subject to an inverse-square force law. We obtain the laws of motion for gravitational or electrical interactions from general relativity--in particular, we find the gravitational field of a mass distribution in an expanding universe by applying perturbation theory to the Robertson-Walker metric. Cosmological expansion induces an ($\\ddot a/a) \\vec r$ force where $a(t)$ is the cosmological scale factor. In a locally Newtonian framework, we show that the $(\\ddot a/a) \\vec r$ term represents the effect of a continuous distribution of cosmological material in Hubble flow, and that the total force on an object, due to the cosmological material plus the matter perturbation, can be represented as the negative gradient of a gravitational potential whose source is the material actually present. We also consider the effect on local dynamics of the cosmological constant. We calculate the perihelion precession of elliptical orbits due to the cosmological constant induced force, and work out a generalized virial relation applicable to gravitationally bound clusters.

Gregory S. Adkins; Jordan McDonnell; Richard N. Fell

2006-12-22T23:59:59.000Z

206

The Effect of Supercritical String Cosmology on the Relic Density of Dark Matter  

E-Print Network [OSTI]

. 3 As various type Ia supernovae projects [4,5] and the WMAP data [1,2] have continually confirmed the existence of dark energy, the cause of universe expansion, Supercritical String Cosmology (SSC) [6,7] arises as a model attempting to formulate... imply that exotic matter has negative pressure, acting like a dark energy term. Also, notice that the factor R increases as ?? decreases. When ?? = 0, ???? = 3.8 ? 1014. Such high enhancement factor is obviously ruled out by observational data, so...

Truong, Phuongmai N

2009-06-09T23:59:59.000Z

207

Protein folding and cosmology  

E-Print Network [OSTI]

Protein denaturing induced by supercooling is interpreted as a process where some or all internal symmetries of the native protein are spontaneously broken. Hence, the free-energy potential corresponding to a folding-funnel landscape becomes temperature-dependent and describes a phase transition. The idea that deformed vortices could be produced in the transition induced by temperature quenching, from native proteins to unfolded conformations is discussed in terms of the Zurek mechanism that implements the analogy between vortices, created in the laboratory at low energy, and the cosmic strings which are thought to have been left after symmetry breaking phase transitions in the early universe. An experiment is proposed to test the above idea which generalizes the cosmological analogy to also encompass biological systems and push a step ahead the view that protein folding is a biological equivalent of the big bang.

González-Diáz, P F

1997-01-01T23:59:59.000Z

208

Cosmological Collider Physics  

E-Print Network [OSTI]

We study the imprint of new particles on the primordial cosmological fluctuations. New particles with masses comparable to the Hubble scale produce a distinctive signature on the non-gaussianities. This feature arises in the squeezed limit of the correlation functions of primordial fluctuations. It consists of particular power law, or oscillatory, behavior that contains information about the masses of new particles. There is an angular dependence that gives information about the spin. We also have a relative phase that crucially depends on the quantum mechanical nature of the fluctuations and can be viewed as arising from the interference between two processes. While some of these features were noted before in the context of specific inflationary scenarios, here we give a general description emphasizing the role of symmetries in determining the final result.

Arkani-Hamed, Nima

2015-01-01T23:59:59.000Z

209

Protein folding and cosmology  

E-Print Network [OSTI]

Protein denaturing induced by supercooling is interpreted as a process where some or all internal symmetries of the native protein are spontaneously broken. Hence, the free-energy potential corresponding to a folding-funnel landscape becomes temperature-dependent and describes a phase transition. The idea that deformed vortices could be produced in the transition induced by temperature quenching, from native proteins to unfolded conformations is discussed in terms of the Zurek mechanism that implements the analogy between vortices, created in the laboratory at low energy, and the cosmic strings which are thought to have been left after symmetry breaking phase transitions in the early universe. An experiment is proposed to test the above idea which generalizes the cosmological analogy to also encompass biological systems and push a step ahead the view that protein folding is a biological equivalent of the big bang.

P. F. Gonzalez-Diaz; C. L. Siguenza

1997-06-04T23:59:59.000Z

210

Cosmology and the weak interaction  

SciTech Connect (OSTI)

The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs.

Schramm, D.N. (Fermi National Accelerator Lab., Batavia, IL (USA)):(Chicago Univ., IL (USA))

1989-12-01T23:59:59.000Z

211

COSMOLOGICAL FAST RADIO BURSTS FROM BINARY WHITE DWARF MERGERS  

SciTech Connect (OSTI)

Recently, Thornton et al. reported the detection of four fast radio bursts (FRBs). The dispersion measures indicate that the sources of these FRBs are at cosmological distance. Given the large full sky event rate ?10{sup 4} sky{sup –1} day{sup –1}, the FRBs are a promising target for multi-messenger astronomy. Here we propose double degenerate, binary white-dwarf (WD) mergers as the source of FRBs, which are produced by coherent emission from the polar region of a rapidly rotating, magnetized massive WD formed after the merger. The basic characteristics of the FRBs, such as the energetics, emission duration and event rate, can be consistently explained in this scenario. As a result, we predict that some FRBs can accompany type Ia supernovae (SNe Ia) or X-ray debris disks. Simultaneous detection could test our scenario and probe the progenitors of SNe Ia, and moreover would provide a novel constraint on the cosmological parameters. We strongly encourage future SN and X-ray surveys that follow up FRBs.

Kashiyama, Kazumi; Mészáros, Peter [Department of Astronomy and Astrophysics, Department of Physics, Center for Particle and Gravitational Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)] [Department of Astronomy and Astrophysics, Department of Physics, Center for Particle and Gravitational Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Ioka, Kunihito, E-mail: kzk15@psu.edu, E-mail: nnp@psu.edu, E-mail: kunihito.ioka@kek.jp [Theory Center, Institute of Particle and Nuclear Studies, KEK, Department of Particle and Nuclear Physics, the Graduate University for Advanced Studies (Sokendai), Tsukuba 305-0801 (Japan)] [Theory Center, Institute of Particle and Nuclear Studies, KEK, Department of Particle and Nuclear Physics, the Graduate University for Advanced Studies (Sokendai), Tsukuba 305-0801 (Japan)

2013-10-20T23:59:59.000Z

212

Signatures of Explosion Models for SN ~Ia & Cosmology  

E-Print Network [OSTI]

We give an overview of the current understanding of Type Ia supernovae relevant for their use as cosmological distance indicators. We present the physical basis to understand their homogeneity of the observed light curves and spectra and the observed correlations. SNe Ia have been well established as distance indicators on the 10 % level. However, the quest for the nature of the dark energy requires improvements in the accuracy to the 2 to 3 % level, we must understand the diversity within the SNe Ia population, and its evolution with redshift. Based on detailed models for the progenitors, explosions, light curves and spectra, we discuss signatures of thermonuclear explosions, and the implications for cosmology. We emphasize the relation between LC properties and spectra because, for local SNe~Ia, the diversity becomes apparent the combination of spectra and LCs whereas, by enlarge, we have to for high-z objects. At some examples, we show how we can actually probe the properties of the progenitor, its environment, and details of the explosion physics.

P. Hoeflich

2004-09-07T23:59:59.000Z

213

Combustion Group Group members  

E-Print Network [OSTI]

Combustion Group Group members: Thierry Poinsot, Emilien Courtine, Luc Vervisch, Benjamin Farcy 2014 #12;Combustion Group Combustion Physics and Modeling Pollutants, Emissions, and Soot Formation Thermoacoustics and Combustion Dynamics Research focus § Examine mechanisms responsible for flame stabilization

Wang, Wei

214

The Nuclear Equation of State and Supernovae James M. Lattimer  

E-Print Network [OSTI]

type of supernova is powered by thermonuclear energy. This type of event involves the end product will be devoted to them. We will point out, however, that because thermonuclear supernovae occur from a quite

Lattimer, James M.

215

Dark-energy dependent test of general relativity at cosmological scales  

E-Print Network [OSTI]

The $\\Lambda$CDM framework offers a remarkably good description of our universe with a very small number of free parameters, which can be determined with high accuracy from currently available data. However, this does not mean that the associated physical quantities, such as the curvature of the universe, have been directly measured. Similarly, general relativity is assumed, but not tested. Testing the relevance of general relativity for cosmology at the background level includes a verification of the relation between its energy contents and the curvature of space. Using an extended Newtonian formulation, we propose an approach where this relation can be tested. Using the recent measurements on cosmic microwave background, baryonic acoustic oscillations and the supernova Hubble diagram, we show that the prediction of general relativity is well verified in the framework of standard $\\Lambda$CDM assumptions, i.e. an energy content only composed of matter and dark energy, in the form of a cosmological constant o...

Zolnierowski, Yves

2015-01-01T23:59:59.000Z

216

Supernova rates and stellar populations  

E-Print Network [OSTI]

We discuss the results about the nature of type Ia Supernovae that can be derived by studying their rates in different stellar populations. While the evolution of SN photometry and spectra can constrain the explosion mechanism, the SN rate depends on the progenitor system. We review the current available data on rates as a function of parent galaxy color, morphology, star formation rate, radio luminosity and environment. By studying the variation of the rates with the color of the parent galaxy, a strong evidence was established that type Ia SNe come from both young and old stars. The dependence of the rates with the radio power of the parent galaxy is best reproduced by a bimodal distribution of delay time between the formation of the progenitor and its explosion as a SN. Cluster early-type galaxies show higher type Ia SN rate with respect to field galaxies, and this effect can be due either to traces of young stars or to differences in the delay time distribution.

F. Mannucci

2007-08-03T23:59:59.000Z

217

Planck Scale Cosmology and Asymptotic Safety in Resummed Quantum Gravity  

E-Print Network [OSTI]

In Weinberg's asymptotic safety approach, a finite dimensional critical surface for a UV stable fixed point generates a theory of quantum gravity with a finite number of physical parameters. We argue that, in an extension of Feynman's original formulation of the theory, we recover this fixed-point UV behavior from an exact re-arrangement of the respective perturbative series. Our results are consistent with the exact field space Wilsonian renormalization group results of Reuter {\\it et al.} and with recent Hopf- algebraic Dyson-Schwinger renormalization theory results of Kreimer. We obtain the first "first principles" predictions of the dimensionless gravitational and cosmological constants and our results support the Planck scale cosmology of Bonanno and Reuter. We conclude with an estimate for the currently observed value of the cosmological constant.

B. F. L. Ward

2010-12-13T23:59:59.000Z

218

Thermodynamics in Loop Quantum Cosmology  

E-Print Network [OSTI]

Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. And the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but are actually also found to be the thermodynamic quantities. This result comes from the energy definition in cosmology (the Misner-Sharp gravitational energy) and is consistent with thermodynamic laws. We prove that within the framework of loop quantum cosmology, the elementary equation of equilibrium thermodynamics is still valid.

Li-Fang Li; Jian-Yang Zhu

2008-12-18T23:59:59.000Z

219

Cosmology with the SKA -- overview  

E-Print Network [OSTI]

The new frontier of cosmology will be led by three-dimensional surveys of the large-scale structure of the Universe. Based on its all-sky surveys and redshift depth, the SKA is destined to revolutionize cosmology, in combination with future optical/ infrared surveys such as Euclid and LSST. Furthermore, we will not have to wait for the full deployment of the SKA in order to see transformational science. In the first phase of deployment (SKA1), all-sky HI intensity mapping surveys and all-sky continuum surveys are forecast to be at the forefront on the major questions of cosmology. We give a broad overview of the major contributions predicted for the SKA. The SKA will not only deliver precision cosmology -- it will also probe the foundations of the standard model and open the door to new discoveries on large-scale features of the Universe.

Maartens, Roy; Jarvis, Matt; Santos, Mario G

2015-01-01T23:59:59.000Z

220

Inflationary Cosmology: Theory and Phenomenology  

E-Print Network [OSTI]

This article gives a brief overview of some of the theory behind the inflationary cosmology, and discusses prospects for constraining inflation using observations. Particular care is given to the question of falsifiability of inflation or of subsets of inflationary models.

Andrew R Liddle

2001-10-18T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Precision Cosmology and the Landscape  

E-Print Network [OSTI]

After reviewing the cosmological constant problem - why is Lambda not huge? - I outline the two basic approaches that had emerged by the late 1980s, and note that each made a clear prediction. Precision cosmological experiments now indicate that the cosmological constant is nonzero. This result strongly favors the environmental approach, in which vacuum energy can vary discretely among widely separated regions in the universe. The need to explain this variation from first principles constitutes an observational constraint on fundamental theory. I review arguments that string theory satisfies this constraint, as it contains a dense discretuum of metastable vacua. The enormous landscape of vacua calls for novel, statistical methods of deriving predictions, and it prompts us to reexamine our description of spacetime on the largest scales. I discuss the effects of cosmological dynamics, and I speculate that weighting vacua by their entropy production may allow for prior-free predictions that do not resort to explicitly anthropic arguments.

Raphael Bousso

2006-11-03T23:59:59.000Z

222

Bimetric gravity is cosmologically viable  

E-Print Network [OSTI]

Bimetric theory describes gravitational interactions in the presence of an extra spin-2 field. Previous work has suggested that its cosmological solutions are generically plagued by instabilities. We show that by taking the Planck mass for the second metric, $M_f$, to be small, these instabilities can be pushed back to unobservably early times. In this limit, the theory approaches general relativity with an effective cosmological constant which is, remarkably, determined by the spin-2 interaction scale. This provides a late-time expansion history which is extremely close to $\\Lambda$CDM, but with a technically-natural value for the cosmological constant. We find $M_f$ should be no larger than the electroweak scale in order for cosmological perturbations to be stable by big-bang nucleosynthesis.

Akrami, Yashar; Könnig, Frank; Schmidt-May, Angnis; Solomon, Adam R

2015-01-01T23:59:59.000Z

223

Investigations of supernovae and supernova remnants in the era of SKA  

E-Print Network [OSTI]

Two main physical mechanisms are used to explain supernova explosions: thermonuclear explosion of a white dwarf(Type Ia) and core collapse of a massive star (Type II and Type Ib/Ic). Type Ia supernovae serve as distance indicators that led to the discovery of the accelerating expansion of the Universe. The exact nature of their progenitor systems however remain unclear. Radio emission from the interaction between the explosion shock front and its surrounding CSM or ISM provides an important probe into the progenitor star's last evolutionary stage. No radio emission has yet been detected from Type Ia supernovae by current telescopes. The SKA will hopefully detect radio emission from Type Ia supernovae due to its much better sensitivity and resolution. There is a 'supernovae rate problem' for the core collapse supernovae because the optically dim ones are missed due to being intrinsically faint and/or due to dust obscuration. A number of dust-enshrouded optically hidden supernovae should be discovered via SKA1-...

Wang, Lingzhi; Zhu, Hui; Tian, Wenwu; Wang, Xiaofeng

2015-01-01T23:59:59.000Z

224

An inhomogeneous fractal cosmological model  

E-Print Network [OSTI]

We present a cosmological model in which the metric allows for an inhomogeneous Universe with no intrinsic symmetries (Stephani models), providing the ideal features to describe a fractal distribution of matter. Constraints on the metric functions are derived using the expansion and redshift relations and allowing for scaling number counts, as expected in a fractal set. The main characteristics of such a cosmological model are discussed.

Fulvio Pompilio; Marco Montuori

2001-11-28T23:59:59.000Z

225

?CDM cosmology from matter only  

E-Print Network [OSTI]

I discuss a matter-only interpretation of {\\Lambda}CDM cosmology, based on conservation of energy and assuming a Machian definition of inertia. {\\Lambda}CDM cosmology can be linked to a Newtonian cosmic potential, subject to a propagating gravitational horizon. In a matter-only universe where total energy is conserved, Machian inertia related to the evolving potential may cause both deceleration and acceleration of recession.

Herman Telkamp

2015-04-08T23:59:59.000Z

226

Cosmological implications of baryon acoustic oscillation (BAO) measurements  

E-Print Network [OSTI]

We derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) and Type Ia supernova (SN) data. We take advantage of high-precision BAO measurements from galaxy clustering and the Ly-alpha forest (LyaF) in the BOSS survey of SDSS-III. BAO data alone yield a high confidence detection of dark energy, and in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Combining BAO and SN data into an "inverse distance ladder" yields a 1.7% measurement of $H_0=67.3 \\pm1.1$ km/s/Mpc. This measurement assumes standard pre-recombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat LCDM cosmology is an important corroboration of this minimal cosmological model. For open LCDM, our BAO+SN+CMB combination yields $\\Omega_m=0.301 \\pm 0.008$ and curvature $\\Omega_k=-0.003 \\pm 0.003$. When we allow more general forms of evolving dark energy, the BAO+SN+CMB parameter constraints remain consistent with flat LCDM. While the overall $\\chi^2$ of model fits is satisfactory, the LyaF BAO measurements are in moderate (2-2.5 sigma) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshifts remain consistent with our constraints, but models where dark matter decays into radiation are sharply limited. Expansion history alone yields an upper limit of 0.56 eV on the summed mass of neutrino species, improving to 0.26 eV if we include Planck CMB lensing. Standard dark energy models constrained by our data predict a level of matter clustering that is high compared to most, but not all, observational estimates. (Abridged)

Éric Aubourg; Stephen Bailey; Julian E. Bautista; Florian Beutler; Vaishali Bhardwaj; Dmitry Bizyaev; Michael Blanton; Michael Blomqvist; Adam S. Bolton; Jo Bovy; Howard Brewington; J. Brinkmann; Joel R. Brownstein; Angela Burden; Nicolás G. Busca; William Carithers; Chia-Hsun Chuang; Johan Comparat; Antonio J. Cuesta; Kyle S. Dawson; Timothée Delubac; Daniel J. Eisenstein; Andreu Font-Ribera; Jian Ge; J. -M. Le Goff; Satya Gontcho A Gontcho; J. Richard Gott III; James E. Gunn; Hong Guo; Julien Guy; Jean-Christophe Hamilton; Shirley Ho; Klaus Honscheid; Cullan Howlett; David Kirkby; Francisco S. Kitaura; Jean-Paul Kneib; Khee-Gan Lee; Dan Long; Robert H. Lupton; Mariana Vargas Magańa; Viktor Malanushenko; Elena Malanushenko; Marc Manera; Claudia Maraston; Daniel Margala; Cameron K. McBride; Jordi Miralda-Escudé; Adam D. Myers; Robert C. Nichol; Pasquier Noterdaeme; Sebastián E. Nuza; Matthew D. Olmstead; Daniel Oravetz; Isabelle Pâris; Nikhil Padmanabhan; Nathalie Palanque-Delabrouille; Kaike Pan; Marcos Pellejero-Ibanez; Will J. Percival; Patrick Petitjean; Matthew M. Pieri; Francisco Prada; Beth Reid; Natalie A. Roe; Ashley J. Ross; Nicholas P. Ross; Graziano Rossi; Jose Alberto Rubińo-Martín; Ariel G. Sánchez; Lado Samushia; Ricardo Tanausú Génova Santos; Claudia G. Scóccola; David J. Schlegel; Donald P. Schneider; Hee-Jong Seo; Erin Sheldon; Audrey Simmons; Ramin A. Skibba; Anže Slosar; Michael A. Strauss; Daniel Thomas; Jeremy L. Tinker; Rita Tojeiro; Jose Alberto Vazquez; Matteo Viel; David A. Wake; Benjamin A. Weaver; David H. Weinberg; W. M. Wood-Vasey; Christophe Yčche; Idit Zehavi; Gong-Bo Zhao

2014-11-18T23:59:59.000Z

227

Radioactive Probes of the Supernova-Contaminated Solar Nebula: Evidence that the Sun was Born in a Cluster  

E-Print Network [OSTI]

We construct a simple model for radioisotopic enrichment of the protosolar nebula by injection from a nearby supernova, based on the inverse square law for ejecta dispersion. We find that the presolar radioisotopes abundances (i.e., in solar masses) demand a nearby supernova: its distance can be no larger than 66 times the size of the protosolar nebula, at a 90% confidence level, assuming 1 solar mass of protosolar material. The relevant size of the nebula depends on its state of evolution at the time of radioactivity injection. In one scenario, a collection of low-mass stars, including our sun, formed in a group or cluster with an intermediate- to high-mass star that ended its life as a supernova while our sun was still a protostar, a starless core, or perhaps a diffuse cloud. Using recent observations of protostars to estimate the size of the protosolar nebula constrains the distance of the supernova at 0.02 to 1.6 pc. The supernova distance limit is consistent with the scales of low-mass stars formation around one or more massive stars, but it is closer than expected were the sun formed in an isolated, solitary state. Consequently, if any presolar radioactivities originated via supernova injection, we must conclude that our sun was a member of such a group or cluster that has since dispersed, and thus that solar system formation should be understood in this context. In addition, we show that the timescale from explosion to the creation of small bodies was on the order of 1.8 Myr (formal 90% confidence range of 0 to 2.2 Myr), and thus the temporal choreography from supernova ejecta to meteorites is important. Finally, we can not distinguish between progenitor masses from 15 to 25 solar masses in the nucleosynthesis models; however, the 20 solar mass model is somewhat preferred.

Leslie W. Looney; John J. Tobin; Brian D. Fields

2006-08-19T23:59:59.000Z

228

Tidally-induced thermonuclear Supernovae  

E-Print Network [OSTI]

We discuss the results of 3D simulations of tidal disruptions of white dwarfs by moderate-mass black holes as they may exist in the cores of globular clusters or dwarf galaxies. Our simulations follow self-consistently the hydrodynamic and nuclear evolution from the initial parabolic orbit over the disruption to the build-up of an accretion disk around the black hole. For strong enough encounters (pericentre distances smaller than about 1/3 of the tidal radius) the tidal compression is reversed by a shock and finally results in a thermonuclear explosion. These explosions are not restricted to progenitor masses close to the Chandrasekhar limit, we find exploding examples throughout the whole white dwarf mass range. There is, however, a restriction on the masses of the involved black holes: black holes more massive than 2 × 10 5 M? swallow a typical 0.6 M ? white dwarf before their tidal forces can overwhelm the star’s selfgravity. Therefore, this mechanism is characteristic for black holes of moderate masses. The material that remains bound to the black hole settles into an accretion disk and produces an X-ray flare close to the Eddington limit of LEdd ? 10 41 erg/s (Mbh/1000M?), typically lasting for a few months. The combination of a peculiar thermonuclear supernova together with an X-ray flare thus whistle-blows the existence of such moderate-mass black holes. The next generation of wide field space-based instruments should be able to detect such events. 1.

Stephan Rosswog; Enrico Ramirez-ruiz; W. Raphael Hix

229

Tidally-induced thermonuclear Supernovae  

E-Print Network [OSTI]

We discuss the results of 3D simulations of tidal disruptions of white dwarfs by moderate-mass black holes as they may exist in the cores of globular clusters or dwarf galaxies. Our simulations follow self-consistently the hydrodynamic and nuclear evolution from the initial parabolic orbit over the disruption to the build-up of an accretion disk around the black hole. For strong enough encounters (pericentre distances smaller than about 1/3 of the tidal radius) the tidal compression is reversed by a shock and finally results in a thermonuclear explosion. These explosions are not restricted to progenitor masses close to the Chandrasekhar limit, we find exploding examples throughout the whole white dwarf mass range. There is, however, a restriction on the masses of the involved black holes: black holes more massive than $2\\times 10^5$ M$_\\odot$ swallow a typical 0.6 M$_\\odot$ dwarf before their tidal forces can overwhelm the star's self-gravity. Therefore, this mechanism is characteristic for black holes of moderate masses. The material that remains bound to the black hole settles into an accretion disk and produces an X-ray flare close to the Eddington limit of $L_{\\rm Edd} \\simeq 10^{41} {\\rm erg/s} M_{\\rm bh}/1000 M$_\\odot$), typically lasting for a few months. The combination of a peculiar thermonuclear supernova together with an X-ray flare thus whistle-blows the existence of such moderate-mass black holes. The next generation of wide field space-based instruments should be able to detect such events.

S. Rosswog; E. Ramirez-Ruiz; W. R. Hix

2008-11-13T23:59:59.000Z

230

CONDITIONS FOR SUPERNOVAE-DRIVEN GALACTIC WINDS  

SciTech Connect (OSTI)

We point out that the commonly assumed condition for galactic outflows, that supernovae (SNe) heating is efficient in the central regions of starburst galaxies, suffers from invalid assumptions. We show that a large filling factor of hot (?10{sup 6} K) gas is difficult to achieve through SNe heating, irrespective of the SN's initial gas temperature and density, its uniformity, or its clumpiness. We instead suggest that correlated supernovae from OB associations in molecular clouds in the central region can drive powerful outflows if the molecular surface density is >10{sup 3} M {sub ?} pc{sup –2}.

Nath, Biman B. [Raman Research Institute, Sadashiva Nagar, Bangalore 560080 (India)] [Raman Research Institute, Sadashiva Nagar, Bangalore 560080 (India); Shchekinov, Yuri, E-mail: biman@rri.res.in, E-mail: yus@sfedu.ru [Department of Physics, Southern Federal University, Rostov on Don, 344090 (Russian Federation)] [Department of Physics, Southern Federal University, Rostov on Don, 344090 (Russian Federation)

2013-11-01T23:59:59.000Z

231

Deflagrations and Detonations in Thermonuclear Supernovae  

E-Print Network [OSTI]

We study a type Ia supernova explosion using three-dimensional numerical simulations based on reactive fluid dynamics. We consider a delayed-detonation model that assumes a deflagration-to-detonation transition. In contrast to the pure deflagration model, the delayed-detonation model releases enough energy to account for a healthy explosion, and does not leave carbon, oxygen, and intermediate-mass elements in central parts of a white dwarf. This removes the key disagreement between simulations and observations, and makes a delayed detonation the mostly likely mechanism for type Ia supernovae.

Vadim N. Gamezo; Alexei M. Khokhlov; Elaine S. Oran

2004-06-03T23:59:59.000Z

232

Hydrogen issue in Core Collapse Supernovae  

E-Print Network [OSTI]

We discuss results of analyzing a time series of selected photospheric-optical spectra of core collapse supernovae (CCSNe). This is accomplished by means of the parameterized supernovae synthetic spectrum (SSp) code ``SYNOW''. Special attention is addressed to traces of hydrogen at early phases, especially for the stripped-envelope SNe (i.e. SNe Ib-c). A thin low mass hydrogen layer extending to very high ejection velocities above the helium shell, is found to be the most likely scenario for Type Ib SNe.

A. Elmhamdi; I. J. Danziger; D. Branch; B. Leibundgut

2006-11-06T23:59:59.000Z

233

Varying constants quantum cosmology  

E-Print Network [OSTI]

We discuss minisuperspace models within the framework of varying physical constants theories including $\\Lambda$-term. In particular, we consider the varying speed of light (VSL) theory and varying gravitational constant theory (VG) using the specific ans\\"atze for the variability of constants: $c(a) = c_0 a^n$ and $G(a)=G_0 a^q$. We find that most of the varying $c$ and $G$ minisuperspace potentials are of the tunneling type which allows to use WKB approximation of quantum mechanics. Using this method we show that the probability of tunneling of the universe "from nothing" ($a=0)$ to a Friedmann geometry with the scale factor $a_t$ is large for growing $c$ models and is strongly suppressed for diminishing $c$ models. As for $G$ varying, the probability of tunneling is large for $G$ diminishing, while it is small for $G$ increasing. In general, both varying $c$ and $G$ change the probability of tunneling in comparison to the standard matter content (cosmological term, dust, radiation) universe models.

Katarzyna Leszczynska; Adam Balcerzak; Mariusz P. Dabrowski

2015-01-26T23:59:59.000Z

234

Composite dark energy: cosmon models with running cosmological term and gravitational coupling  

E-Print Network [OSTI]

In the recent literature on dark energy (DE) model building we have learnt that cosmologies with variable cosmological parameters can mimic more traditional DE pictures exclusively based on scalar fields (e.g. quintessence and phantom). In a previous work we have illustrated this situation within the context of a renormalization group running cosmological term, Lambda. Here we analyze the possibility that both the cosmological term and the gravitational coupling, G, are running parameters within a more general framework (a variant of the so-called ``LXCDM models'') in which the DE fluid can be a mixture of a running Lambda and another dynamical entity X (the ``cosmon'') which may behave quintessence-like or phantom-like. We compute the effective EOS parameter, w, of this composite fluid and show that the LXCDM can mimic to a large extent the standard LCDM model while retaining features hinting at its potential composite nature (such as the smooth crossing of the cosmological constant boundary w=-1). We further argue that the LXCDM models can cure the cosmological coincidence problem. All in all we suggest that future experimental studies on precision cosmology should take seriously the possibility that the DE fluid can be a composite medium whose dynamical features are partially caused and renormalized by the quantum running of the cosmological parameters.

Javier Grande; Joan Sola; Hrvoje Stefancic

2006-12-16T23:59:59.000Z

235

SALT2: using distant supernovae to improve the use of Type Ia supernovae as distance indicators  

E-Print Network [OSTI]

We present an empirical model of Type Ia supernovae spectro-photometric evolution with time. The model is built using a large data set including light-curves and spectra of both nearby and distant supernovae, the latter being observed by the SNLS collaboration. We derive the average spectral sequence of Type Ia supernovae and their main variability components including a color variation law. The model allows us to measure distance moduli in the spectral range 2500-8000 A with calculable uncertainties, including those arising from variability of spectral features. Thanks to the use of high-redshift SNe to model the rest-frame UV spectral energy distribution, we are able to derive improved distance estimates for SNe Ia in the redshift range 0.8supernovae.

J. Guy; P. Astier; S. Baumont; D. Hardin; R. Pain; N. Regnault; S. Basa; R. G. Carlberg; A. Conley; S. Fabbro; D. Fouchez; I. M. Hook; D. A. Howell; K. Perrett; C. J. Pritchet; J. Rich; M. Sullivan; P. Antilogus; E. Aubourg; G. Bazin; J. Bronder; M. Filiol; N. Palanque-Delabrouille; P. Ripoche; V. Ruhlmann-Kleider

2007-01-29T23:59:59.000Z

236

Type Ia supernova rate studies from the SDSS-II Supernova Study  

SciTech Connect (OSTI)

The author presents new measurements of the type Ia SN rate from the SDSS-II Supernova Survey. The SDSS-II Supernova Survey was carried out during the Fall months (Sept.-Nov.) of 2005-2007 and discovered {approx} 500 spectroscopically confirmed SNe Ia with densely sampled (once every {approx} 4 days), multi-color light curves. Additionally, the SDSS-II Supernova Survey has discovered several hundred SNe Ia candidates with well-measured light curves, but without spectroscopic confirmation of type. This total, achieved in 9 months of observing, represents {approx} 15-20% of the total SNe Ia discovered worldwide since 1885. The author describes some technical details of the SN Survey observations and SN search algorithms that contributed to the extremely high-yield of discovered SNe and that are important as context for the SDSS-II Supernova Survey SN Ia rate measurements.

Dilday, Benjamin; /Chicago U.

2008-08-01T23:59:59.000Z

237

A New Determination of the High Redshift Type Ia Supernova Rates with the Hubble Space Telescope Advanced Camera for Surveys  

E-Print Network [OSTI]

Schmidt, B. P. , 2003, in Supernovae and Gamma Ray Bursts,for identifying Type Ia supernovae (although spectroscopicfor future high-statistics supernovae searches in which

2008-01-01T23:59:59.000Z

238

The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star  

E-Print Network [OSTI]

magnitudes of Type IA supernovae. Astrophys. J. Lett. 413,from 42 High-Redshift Supernovae. Astrophys. J. 517, 565–Observational Evidence from Supernovae for an Accelerating

2008-01-01T23:59:59.000Z

239

Galaxy Cosmological Mass Function  

E-Print Network [OSTI]

We study the galaxy cosmological mass function (GCMF) in a semi-empirical relativistic approach using observational data provided by galaxy redshift surveys. Starting from the theory of Ribeiro & Stoeger (2003, arXiv:astro-ph/0304094) between the mass-to-light ratio, the selection function obtained from the luminosity function (LF) data and the luminosity density, the average luminosity $L$ and the average galactic mass $\\mathcal{M}_g$ are computed in terms of the redshift. $\\mathcal{M}_g$ is also alternatively estimated by a method that uses the galaxy stellar mass function (GSMF). Comparison of these two forms of deriving the average galactic mass allows us to infer a possible bias introduced by the selection criteria of the survey. We used the FORS Deep Field galaxy survey sample of 5558 galaxies in the redshift range $0.5 light ratio and its GSMF data. Assuming ${\\mathcal{M}_{g_0}} \\approx 10^{11} \\mathcal{M}_\\odot$ as the local value of the average galactic mass, the LF approach results in $L_{B} \\propto (1+z)^{(2.40 \\pm 0.03)}$ and $\\mathcal{M}_g \\propto (1+z)^{(1.1\\pm0.2)}$. However, using the GSMF results produces $\\mathcal{M}_g \\propto (1+z)^{(-0.58 \\pm 0.22)}$. We chose the latter result as it is less biased. We then obtained the theoretical quantities of interest, such as the differential number counts, to calculate the GCMF, which can be fitted by a Schechter function. The derived GCMF follows theoretical predictions in which the less massive objects form first, being followed later by more massive ones. In the range $0.5 < z < 2.0$ the GCMF has a strong variation that can be interpreted as a higher rate of galaxy mergers or as a strong evolution in the star formation history of these galaxies.

Amanda R. Lopes; Alvaro Iribarrem; Marcelo B. Ribeiro; William R. Stoeger

2014-12-03T23:59:59.000Z

240

Plasma Redshift, Time Dilation, and Supernovas Ia  

E-Print Network [OSTI]

The measurements of the absolute magnitudes and redshifts of supernovas Ia show that conventional physics, which includes plasma redshift, fully explains the observed magnitude-redshift relation of the supernovas. The only parameter that is required is the Hubble constant, which in principle can be measured independently. The contemporary theory of the expansion of the universe (Big Bang) requires in addition to the Hubble constant several adjustable parameters, such as an initial explosion, the dark matter parameter, and a time adjustable dark energy parameter for explaining the supernova Ia data. The contemporary Big Bang theory also requires time dilation of distant events as an inherent premise. The contention is usually that the light curves of distant supernovas show or even prove the time dilation. In the present article, we challenge this assertion. We document and show that the previously reported data in fact indicate that there is no time dilation. The data reported by Riess et al. in the Astrophysical Journal in June 2004 confirm the plasma redshift, the absence of time dilation, dark matter, and dark energy.

Ari Brynjolfsson

2004-07-20T23:59:59.000Z

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241

GRAVITATIONAL FIELD SHIELDING AND SUPERNOVA EXPLOSIONS  

SciTech Connect (OSTI)

A new mechanism for supernova explosions called gravitational field shielding is proposed, in accord with a five-dimensional fully covariant Kaluza-Klein theory with a scalar field that unifies the four-dimensional Einsteinian general relativity and Maxwellian electromagnetic theory. It is shown that a dense compact collapsing core of a star will suddenly turn off or completely shield its gravitational field when the core collapses to a critical density, which is inversely proportional to the square of mass of the core. As the core suddenly turns off its gravity, the extremely large pressure immediately stops the core collapse and pushes the mantle material of supernova moving outward. The work done by the pressure in the expansion can be the order of energy released in a supernova explosion. The gravity will resume and stop the core from a further expansion when the core density becomes less than the critical density. Therefore, the gravitational field shielding leads a supernova to impulsively explode and form a compact object such as a neutron star as a remnant. It works such that a compressed spring will shoot the oscillator out when the compressed force is suddenly removed.

Zhang, T. X. [Physics Department, Alabama A and M University, Normal, AL 35762 (United States)

2010-12-20T23:59:59.000Z

242

Null geodesics and observational cosmology  

E-Print Network [OSTI]

The Universe is not isotropic or spatially homogeneous on local scales. The averaging of local inhomogeneities in general relativity can lead to significant dynamical effects on the evolution of the Universe, and even if the effects are at the 1% level they must be taken into account in a proper interpretation of cosmological observations. We discuss the effects that averaging (and inhomogeneities in general) can have on the dynamical evolution of the Universe and the interpretation of cosmological data. All deductions about cosmology are based on the paths of photons. We discuss some qualitative aspects of the motion of photons in an averaged geometry, particularly within the context of the luminosity distance-redshift relation in the simple case of spherical symmetry.

A. A. Coley

2008-12-24T23:59:59.000Z

243

Explosion Models for Type Ia Supernovae: A Comparison with Observed Light Curves, distances, H_o and q_o  

E-Print Network [OSTI]

Theoretical monochromatic light curves and photospheric expansion velocities are compared with observations of 27 Type Ia supernovae (SNe Ia). A set of 37 models has been considered which encompasses all currently discussed explosion scenarios for Type Ia supernovae including deflagrations, detonations, delayed detonations, pulsating delayed detonations and tamped detonations of Chandra- mass, and Helium detonations of low mass white dwarfs. The explosions are calculated using one-dimensional Lagrangian hydro and radiation-hydro codes with incorporated nuclear networks. Subsequently, light curves are constructed using our LC scheme which includes an implicit radiation transport, expansion opacities, a Monte-Carlo $\\gamma $-ray transport, and molecular and dust formation. For some supernovae, results of detailed non-LTE calculations have been considered. Observational properties of our series of models are discussed, the relation between the absolute brightness, post-maximum decline rates, the colors at several moments of time, etc. All models with a Ni production larger than 0.4 solar masses produce light curves of similar brightness. The influence of the cosmological red shift on the light curves and on the correction for interstellar reddening is discussed. Based on data rectification of the standard deviation, a quantitative procedure to fit the observations has been used to the determine the free parameters, i.e. the correct model, the distance, the reddening, and the time of the explosion. The results are discussed in detail and applied to determine Ho and qo.

P. Hoeflich; A. Khokkhlov

1996-02-06T23:59:59.000Z

244

SUPERNOVA LIGHT CURVES POWERED BY FALLBACK ACCRETION  

SciTech Connect (OSTI)

Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time ({approx}>days) power potentially associated with the accretion of this 'fallback' material could significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as M-dot {proportional_to}t{sup -5/3} at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse out efficiently. The resulting light curves are different and more diverse than previous fallback supernova models which ignored the input of accretion power and produced short-lived, dim transients. The possible outcomes when fallback accretion power is significant include super-luminous ({approx}> 10{sup 44} erg s{sup -1}) Type II events of both short and long durations, as well as luminous Type I events from compact stars that may have experienced significant mass loss. Accretion power may unbind the remaining infalling material, causing a sudden decrease in the brightness of some long duration Type II events. This scenario may be relevant for explaining some of the recently discovered classes of peculiar and rare supernovae.

Dexter, Jason; Kasen, Daniel, E-mail: jdexter@berkeley.edu [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States)

2013-07-20T23:59:59.000Z

245

Probing thermonuclear supernova explosions with neutrinos  

E-Print Network [OSTI]

Aims: We present neutrino light curves and energy spectra for two representative type Ia supernova explosion models: a pure deflagration and a delayed detonation. Methods: We calculate the neutrino flux from $\\beta$ processes using nuclear statistical equilibrium abundances convoluted with approximate neutrino spectra of the individual nuclei and the thermal neutrino spectrum (pair+plasma). Results: Although the two considered thermonuclear supernova explosion scenarios are expected to produce almost identical electromagnetic output, their neutrino signatures appear vastly different, which allow an unambiguous identification of the explosion mechanism: a pure deflagration produces a single peak in the neutrino light curve, while the addition of the second maximum characterizes a delayed-detonation. We identified the following main contributors to the neutrino signal: (1) weak electron neutrino emission from electron captures (in particular on the protons Co55 and Ni56) and numerous beta-active nuclei produced by the thermonuclear flame and/or detonation front, (2) electron antineutrinos from positron captures on neutrons, and (3) the thermal emission from pair annihilation. We estimate that a pure deflagration supernova explosion at a distance of 1 kpc would trigger about 14 events in the future 50 kt liquid scintillator detector and some 19 events in a 0.5 Mt water Cherenkov-type detector. Conclusions: While in contrast to core-collapse supernovae neutrinos carry only a very small fraction of the energy produced in the thermonuclear supernova explosion, the SN Ia neutrino signal provides information that allows us to unambiguously distinguish between different possible explosion scenarios. These studies will become feasible with the next generation of proposed neutrino observatories.

A. Odrzywolek; T. Plewa

2011-03-27T23:59:59.000Z

246

Cosmological dark energy effects from entanglement  

E-Print Network [OSTI]

The thorny issue of relating information theory to cosmology is here addressed by assuming a possible connection between quantum entanglement measures and observable universe. In particular, we propose a cosmological toy model, where the equation of state of the cosmological fluid, which drives the today observed cosmic acceleration, can be inferred from quantum entanglement between different cosmological epochs. In such a way the dynamical dark energy results as byproduct of quantum entanglement.

S. Capozziello; O. Luongo; S. Mancini

2013-02-24T23:59:59.000Z

247

Cosmological science enabled by Planck  

E-Print Network [OSTI]

Planck will be the first mission to map the entire cosmic microwave background (CMB) sky with mJy sensitivity and resolution better than 10'. The science enabled by such a mission spans many areas of astrophysics and cosmology. In particular it will lead to a revolution in our understanding of primary and secondary CMB anisotropies, the constraints on many key cosmological parameters will be improved by almost an order of magnitude (to sub-percent levels) and the shape and amplitude of the mass power spectrum at high redshift will be tightly constrained.

Martin White

2006-06-27T23:59:59.000Z

248

Quasar Structure and Cosmological Feedback  

E-Print Network [OSTI]

Feedback from quasars and AGNs is being invoked frequently in several cosmological settings. Currently, order of magnitude, or more, uncertainties in the structure of both the wind and the 'obscuring torus' make predictions highly uncertain. To make testable models of this 'cosmological feedback' it is essential to understand the detailed structure of AGNs sufficiently well to predict their properties for the whole quasar population, at all redshifts. Progress in both areas is rapid, and I describe the near-term prospects for reducing these uncertainties for 'slow' (non-relativistic) AGN winds and the obscuring torus.

Martin Elvis

2006-06-05T23:59:59.000Z

249

Stringy Model of Cosmological Dark Energy  

E-Print Network [OSTI]

A string field theory(SFT) nonlocal model of the cosmological dark energy providing w<-1 is briefly surveyed. We summarize recent developments and open problems, as well as point out some theoretical issues related with others applications of the SFT nonlocal models in cosmology, in particular, in inflation and cosmological singularity.

Irina Ya. Aref'eva

2007-10-16T23:59:59.000Z

250

A theoretician's analysis of the supernova data and the limitations in determining the nature of dark energy  

E-Print Network [OSTI]

Current cosmological observations show a strong signature of the existence of a dark energy component with negative pressure. The most obvious candidate for this dark energy is the cosmological constant (with the equation of state w_X=p/\\rho=-1), which, however, raises several theoretical difficulties. This has led to models for dark energy component which evolves with time. We discuss certain questions related to the determination of the nature of dark energy component from observations of high redshift supernova. The main results of our analysis are: (i) Even if the precise value of w_X is known from observations, it is not possible to determine the nature of the unknown dark energy source using only kinematical and geometrical measurements. We have given explicit examples to show that different types of sources can give rise to a given w_X. (ii) Although the full data set of supernova observations (which are currently available) strongly rule out models without dark energy, the high (z>0.25) and low (z<0.25) redshift data sets, individually, admit decelerating models with zero dark energy. Any possible evolution in the absolute magnitude of the supernovae, if detected, might allow the decelerating models to be consistent with the data. (iii) We have introduced two parameters, which can be obtained entirely from theory, to study the sensitivity of the luminosity distance on w_X. Using these two parameters, we have argued that although one can determine the present value of w_X accurately from the data, one cannot constrain the evolution of w_X.

T. Padmanabhan; T. Roy Choudhury

2003-06-18T23:59:59.000Z

251

PECULIAR OPTICAL AND IR BEHAVIOUR IN TYPE I SUPERNOVAE, AND THE ORIGIN OF THE 1.2 ABSORPTION  

E-Print Network [OSTI]

Wheeler, le. , 1984. In "Supernovae as distance indicators",lR. , 1985. In "Dust in supernovae and supernova remnants",and IR behaviour in type I supernovae, and the origin of the

Graham, J.R.

2011-01-01T23:59:59.000Z

252

Gravitational Instability of Yang-Mills Cosmologies  

E-Print Network [OSTI]

The gravitational instability of Yang-Mills cosmologies is numerically studied with the hamiltonian formulation of the spherically symmetric Einstein-Yang-Mills equations with SU(2) gauge group. On the short term, the expansion dilutes the energy densities of the Yang-Mills fluctuations due to their conformal invariance. In this early regime, the gauge potentials appear oscillating quietly in an interaction potential quite similar to the one of the homogeneous case. However, on the long term, the expansion finally becomes significantly inhomogeneous and no more mimics a conformal transformation of the metric. Thereafter, the Yang-Mills fluctuations enter a complex non-linear regime, accompanied by diffusion, while their associated energy contrasts grow.

A. Fuzfa

2003-10-06T23:59:59.000Z

253

Asymmetric cyclic evolution in polymerised cosmology  

SciTech Connect (OSTI)

The dynamical systems methods are used to study evolution of the polymerised scalar field cosmologies with the cosmological constant. We have found all evolutional paths admissible for all initial conditions on the two-dimensional phase space. We have shown that the cyclic solutions are generic. The exact solution for polymerised cosmology is also obtained. Two basic cases are investigated, the polymerised scalar field and the polymerised gravitational and scalar field part. In the former the division on the cyclic and non-cyclic behaviour is established following the sign of the cosmological constant. The value of the cosmological constant is upper bounded purely from the dynamical setting.

Hrycyna, Orest [Department of Theoretical Physics, Faculty of Philosophy, The John Paul II Catholic University of Lublin, Al. Rac?awickie 14, 20-950 Lublin (Poland); Mielczarek, Jakub; Szyd?owski, Marek, E-mail: hrycyna@kul.lublin.pl, E-mail: jakub.mielczarek@uj.edu.pl, E-mail: uoszydlo@cyf-kr.edu.pl [Astronomical Observatory, Jagiellonian University, Orla 171, 30-244 Kraków (Poland)

2009-12-01T23:59:59.000Z

254

Electric Time in Quantum Cosmology  

E-Print Network [OSTI]

Effective quantum cosmology is formulated with a realistic global internal time given by the electric vector potential. New possibilities for the quantum behavior of space-time are found, and the high-density regime is shown to be very sensitive to the specific form of state realized.

Stephon Alexander; Martin Bojowald; Antonino Marciano; David Simpson

2012-12-10T23:59:59.000Z

255

Numerical Simulations in Cosmology I  

E-Print Network [OSTI]

The purpose of these lectures is to give a short introduction into a very vast field of numerical simulations for cosmological applications. I focus on major features of the simulations: the equations, main numerical techniques, effects of resolution, and methods of halo identification.

A. Klypin

1996-05-30T23:59:59.000Z

256

UV Spectroscopy of Type Ia Supernovae at Low- and High-Redshift  

E-Print Network [OSTI]

Spectroscopy of Type Ia Supernovae at Low- and High-RedshiftUV properties of Type Ia Supernovae. The low-redshift studyULDA Access Guide No. 6: Supernovae, The Netherlands: ESA

Nugent, Peter

2005-01-01T23:59:59.000Z

257

Measuring Type Ia Supernova Distances and Redshifts From Their Multi-band Light Curves  

E-Print Network [OSTI]

curve, http://supernovae.in2p3.fr/ ? guy/salt/index.htmlfor large numbers of supernovae; so many that it would becosmology:distance scale, supernovae:general Introduction

Kim, Alex G.; Miquel, Ramon

2007-01-01T23:59:59.000Z

258

Type Ia supernova rate at a redshift of ~;0.1  

E-Print Network [OSTI]

since the Big Bang: Supernovae and Gamma-Ray Bursts, held 3-rst the EROS search for supernovae is reviewed in Sect. 2.2. The EROS search for supernovae The EROS experiment used a

2004-01-01T23:59:59.000Z

259

A Progress Report on the Berkeley Search for Distant Supernovae to Measure {Omega}  

E-Print Network [OSTI]

Search for Distant Supernovae to Measure Q C. Pennypacker,Search for Distant Supernovae to Measure n C. Pennypacker,Search for Distant Supernovae to Measure Q Carl Pennypacker,

Pennypacker, Carl R.

2008-01-01T23:59:59.000Z

260

GRB 020410: A Gamma-ray burst afterglow discovered by its supernova light  

E-Print Network [OSTI]

high-velocity Type Ib/c supernovae such as SN 1998bw. Otherwith the luminous Type Ic supernovae 1998bw (Galama et al.a link between GRBs and supernovae. However GRB 980425 was a

2004-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Three-dimensional numerical simulations of Rayleigh-Taylor unstable flames in type Ia supernovae  

E-Print Network [OSTI]

Unstable Flames in Type Ia Supernovae M. Zingale 1 , S. E.Subject headings: supernovae: general — white dwarfs —ame in Type Ia supernovae (SNe Ia) is well recognized (M¨

Zingale, M.; Woosley, S.E.; Rendleman, C.A.; Day, M.S.; Bell, J.B.

2005-01-01T23:59:59.000Z

262

Discovery of the Most Distant Supernovae and the Quest for Omega  

E-Print Network [OSTI]

of the Most Distant Supernovae and the Quest for .Q G.Discovery of the Most Distant Supernovae and the Quest for QOF THE MOST DISTANT SUPERNOVAE AND THE QUEST FOR fl* GERSON

Goldhaber, G.

2008-01-01T23:59:59.000Z

263

Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study  

E-Print Network [OSTI]

Highlight - The Physics of Supernovae, ESO/MPA/MPE Workshop,Evolution in high-redshift supernovae Fig. 8 “Ca ii H&K”SN 1991T/SN 1999aa-like supernovae. 1. Introduction Type Ia

Garavini, G.; Supernova Cosmology Project

2008-01-01T23:59:59.000Z

264

THE CARNEGIE SUPERNOVA PROJECT: FIRST NEAR-INFRARED HUBBLE DIAGRAM TO z approx 0.7  

SciTech Connect (OSTI)

The Carnegie Supernova Project (CSP) is designed to measure the luminosity distance for Type Ia supernovae (SNe Ia) as a function of redshift, and to set observational constraints on the dark energy contribution to the total energy content of the universe. The CSP differs from other projects to date in its goal of providing an I-band rest-frame Hubble diagram. Here, we present the first results from near-infrared observations obtained using the Magellan Baade telescope for SNe Ia with 0.1 supernova cosmology programs. Finally, we conclude that either the dust affecting the luminosities of SNe Ia has a different extinction law (R{sub V} = 1.8) than that in the Milky Way (where R{sub V} = 3.1), or that there is an additional intrinsic color term with luminosity for SNe Ia, independent of the decline rate. Understanding and disentangling these effects is critical for minimizing the systematic uncertainties in future SN Ia cosmology studies.

Freedman, Wendy L.; Burns, Christopher R.; Wyatt, Pamela; Persson, S. E.; Madore, Barry F.; Kelson, Daniel D.; Murphy, D. C.; Sturch, Laura [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Phillips, M. M.; Contreras, Carlos; Folatelli, Gaston; Gonzalez, E. Sergio; Morrell, Nidia; Roth, Miguel; Stritzinger, Maximilian [Carnegie Institution of Washington, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Hamuy, Mario [Universidad de Chile, Departmento de Astronomia, Casilla 36-D, Santiago (Chile); Hsiao, Eric [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Stn CSC, Victoria, BC V8W 3P6 (Canada); Suntzeff, Nick B. [Physics Department, Texas A and M University, College Station, TX 77843 (United States); Astier, P.; Balland, C. [LPNHE, CNRS-IN2P3 and Universites Paris VI and VII, 4 place Jussieu, 75252 Paris Cedex 05 (France)

2009-10-20T23:59:59.000Z

265

Semi-supervised Learning for Photometric Supernova Classification  

E-Print Network [OSTI]

We present a semi-supervised method for photometric supernova typing. Our approach is to first use the nonlinear dimension reduction technique diffusion map to detect structure in a database of supernova light curves and subsequently employ random forest classification on a spectroscopically confirmed training set to learn a model that can predict the type of each newly observed supernova. We demonstrate that this is an effective method for supernova typing. As supernova numbers increase, our semi-supervised method efficiently utilizes this information to improve classification, a property not enjoyed by template based methods. Applied to supernova data simulated by Kessler et al. (2010b) to mimic those of the Dark Energy Survey, our methods achieve (cross-validated) 96% Type Ia purity and 86% Type Ia efficiency on the spectroscopic sample, but only 56% Type Ia purity and 48% efficiency on the photometric sample due to their spectroscopic followup strategy. To improve the performance on the photometric sample...

Richards, Joseph W; Freeman, Peter E; Schafer, Chad M; Poznanski, Dovi

2011-01-01T23:59:59.000Z

266

THE DISCOVERY OF THE MOST DISTANT KNOWN TYPE Ia SUPERNOVA AT REDSHIFT 1.914  

SciTech Connect (OSTI)

We present the discovery of a Type Ia supernova (SN) at redshift z = 1.914 from the CANDELS multi-cycle treasury program on the Hubble Space Telescope (HST). This SN was discovered in the infrared using the Wide-Field Camera 3, and it is the highest-redshift Type Ia SN yet observed. We classify this object as a SN Ia by comparing its light curve and spectrum with those of a large sample of Type Ia and core-collapse SNe. Its apparent magnitude is consistent with that expected from the {Lambda}CDM concordance cosmology. We discuss the use of spectral evidence for classification of z > 1.5 SNe Ia using HST grism simulations, finding that spectral data alone can frequently rule out SNe II, but distinguishing between SNe Ia and SNe Ib/c can require prohibitively long exposures. In such cases, a quantitative analysis of the light curve may be necessary for classification. Our photometric and spectroscopic classification methods can aid the determination of SN rates and cosmological parameters from the full high-redshift CANDELS SN sample.

Jones, David O.; Rodney, Steven A.; Riess, Adam G. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Dahlen, Tomas; Casertano, Stefano; Koekemoer, Anton [Space Telescope Science Institute, Baltimore, MD 21218 (United States); McCully, Curtis; Keeton, Charles R.; Patel, Brandon [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); Frederiksen, Teddy F.; Hjorth, Jens [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Strolger, Louis-Gregory [Department of Physics, Western Kentucky University, Bowling Green, KY 42101 (United States); Wiklind, Tommy G. [Joint ALMA Observatory, ESO, Santiago (Chile); Challis, Peter [Harvard/Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Graur, Or [School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Hayden, Brian; Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Weiner, Benjamin J. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); and others

2013-05-10T23:59:59.000Z

267

Towards simulating star formation in turbulent high-z galaxies with mechanical supernova feedback  

E-Print Network [OSTI]

Feedback from supernovae is essential to understanding the self-regulation of star formation in galaxies. However, the efficacy of the process in a cosmological context remains unclear due to excessive radiative losses during the shock propagation. To better understand the impact of SN explosions on the evolution of galaxies, we perform a suite of high-resolution (12 pc), zoom-in cosmological simulations of a Milky Way-like galaxy at z=3 with adaptive mesh refinement. We find that SN explosions can efficiently regulate star formation, leading to the stellar mass and metallicity consistent with the observed mass-metallicity relation and stellar mass-halo mass relation at z~3. This is achieved by making three important changes to the classical feedback scheme: i) the different phases of SN blast waves are modelled directly by injecting radial momentum expected at each stage, ii) the realistic time delay of SNe, commencing at as early as 3 Myr, is required to disperse very dense gas before a runaway collapse set...

Kimm, Taysun; Devriendt, Julien; Dubois, Yohan; Slyz, Adrianne

2015-01-01T23:59:59.000Z

268

Tycho Brahe's supernova: light from centuries past  

E-Print Network [OSTI]

The light curve of SN 1572 is described in the terms used nowadays to characterize SNeIa. By assembling the records of the observations done in 1572--74 and evaluating their uncertainties, it is possible to recover the light curve and the color evolution of this supernova. It is found that, within the SNe Ia family, the event should have been a SNIa with a normal rate of decline, its stretch factor being {\\it s} $\\sim$ 0.9. Visual light curve near maximum, late--time decline and the color evolution sustain this conclusion. After correcting for extinction, the luminosity of this supernova is found to be M$_{V}$ $=$ --19.58 --5 log (D/3.5 kpc) $\\pm$ 0.42.

Pilar Ruiz-Lapuente

2003-08-30T23:59:59.000Z

269

Tycho Brahe's supernova: light from centuries past  

E-Print Network [OSTI]

The light curve of SN 1572 is described in the terms used nowadays to characterize SNeIa. By assembling the records of the observations done in 1572--74 and evaluating their uncertainties, it is possible to recover the light curve and the color evolution of this supernova. It is found that, within the SNe Ia family, the event should have been a SNIa with a normal rate of decline, its stretch factor being {\\it s} $\\sim$ 0.9. Visual light curve near maximum, late--time decline and the color evolution sustain this conclusion. After correcting for extinction, the luminosity of this supernova is found to be M$_{V}$ $=$ --19.58 --5 log (D/3.5 kpc) $\\pm$ 0.42.

Ruiz-Lapuente, P

2003-01-01T23:59:59.000Z

270

Reverse-Shock in Tycho's Supernova Remnant  

E-Print Network [OSTI]

Thermal X-ray emission from young supernova remnants (SNRs) is usually dominated by the emission lines of the supernova (SN) ejecta, which are widely believed being crossed and thus heated by the inwards propagating reverse shock (RS). Previous works using imaging X-ray data have shown that the ejecta are heated by the RS by locating the peak emission region of the most recently ionized matter, which is found well separated towards the inside from the outermost boundary. Here we report the discovery of a systematic increase of the Sulfur (S) to Silicon (Si) K$\\alpha$ line flux ratio with radius in Tycho's SNR. This allows us, for the first time, to present continuous radial profiles of the ionization age and, furthermore, the elapsed ionization time since the onset of the ionization, which tells the propagation history of the ionization front into the SNR ejecta.

Lu, F J; Zheng, S J; Zhang, S N; Long, X; Aschenbach, B

2015-01-01T23:59:59.000Z

271

Merging White Dwarfs and Thermonuclear Supernovae  

E-Print Network [OSTI]

Thermonuclear supernovae result when interaction with a companion reignites nuclear fusion in a carbon-oxygen white dwarf, causing a thermonuclear runaway, a catastrophic gain in pressure, and the disintegration of the whole white dwarf. It is usually thought that fusion is reignited in near-pycnonuclear conditions when the white dwarf approaches the Chandrasekhar mass. I briefly describe two long-standing problems faced by this scenario, and our suggestion that these supernovae instead result from mergers of carbon-oxygen white dwarfs, including those that produce sub-Chandrasekhar mass remnants. I then turn to possible observational tests, in particular those that test the absence or presence of electron captures during the burning.

van Kerkwijk, Marten H

2012-01-01T23:59:59.000Z

272

X-rays from Supernova Remnants  

E-Print Network [OSTI]

A summary of X-ray observations of supernova remnants is presented including the explosion fragment A of the Vela SNR, Tycho, N132D, RX J0852-4622, the Crab Nebula and the 'bulls eye', and SN 1987A, high-lighting the progress made with Chandra and XMM-Newton and touching upon the questions which arise from these observations and which might inspire future research.

B. Aschenbach

2002-08-28T23:59:59.000Z

273

Nucleosynthesis in O-Ne-Mg Supernovae  

SciTech Connect (OSTI)

We have studied detailed nucleosynthesis in the shocked surface layers of an oxygen-neon-magnesium core collapse supernova with an eye to determining whether the conditions are suitable for r-process nucleosynthesis. We find no such conditions in an unmodified model, but do find overproduction of N=50 nuclei (previously seen in early neutron-rich neutrino winds) in amounts that, if ejected, would pose serious problems for Galactic chemical evolution.

Hoffman, R D; Janka, H; Muller, B

2007-12-18T23:59:59.000Z

274

Type Ia Supernovae M100 in Early 2006  

E-Print Network [OSTI]

://rsdwww.nrl.navy.mil/7212/montes/snetax.html 2.) http://www.lbl.gov/ScienceArticles/Archive/sabl/2005/October/04supernovae.html

Crenshaw, Michael

275

Confirmed: Stellar Behemoth Self-Destructs in Type IIb Supernova  

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

National Laboratory (Berkeley Lab), to expose fleeting cosmic events such as supernovae. For the first time ever, scientists have direct confirmation that a Wolf-Rayet...

276

Acquiring information about neutrino parameters by detecting supernova neutrinos  

SciTech Connect (OSTI)

We consider the supernova shock effects, the Mikheyev-Smirnov-Wolfenstein effects, the collective effects, and the Earth matter effects in the detection of type II supernova neutrinos on the Earth. It is found that the event number of supernova neutrinos depends on the neutrino mass hierarchy, the neutrino mixing angle {theta}{sub 13}, and neutrino masses. Therefore, we propose possible methods to identify the mass hierarchy and acquire information about {theta}{sub 13} and neutrino masses by detecting supernova neutrinos. We apply these methods to some current neutrino experiments.

Huang, Ming-Yang; Guo, Xin-Heng [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Young, Bing-Lin [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 5001 (United States); Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2010-08-01T23:59:59.000Z

277

Earth Matter Effects in Detection of Supernova Neutrinos  

E-Print Network [OSTI]

We calculated the matter effect, including both the Earth and supernova, on the detection of neutrinos from type II supernovae at the proposed Daya Bay reactor neutrino experiment. It is found that apart from the dependence on the flip probability P_H inside the supernova and the mass hierarchy of neutrinos, the amount of the Earth matter effect depends on the direction of the incoming supernova neutrinos, and reaches the biggest value when the incident angle of neutrinos is around 93^\\circ. In the reaction channel \\bar{\

X. -H. Guo; Bing-Lin Young

2006-05-11T23:59:59.000Z

278

Massive binaries, Wolf-Rayet stars and supernova progenitors  

E-Print Network [OSTI]

Binary stars are important for a full understanding of stellar evolution. We present a summary of how predictions of the relative supernova rates varies between single and binary stars. We also show how the parameter space of different supernova types differs between single and binary stars. We then consider an important question of how to infer a supernova progenitor's properties from pre-explosion imaging and present rescent work of producing synthe tic colours for our stellar models to make a direct comparison with any detections or limits obtained on supernova progentiors from pre-explosion images.

J. J. Eldridge

2006-12-17T23:59:59.000Z

279

THE POWER OF THERMONUCLEAR SUPERNOVAE AFTER ONE YEAR.  

E-Print Network [OSTI]

??Type Ia supernovae (SNe Ia), the thermonuclear explosion of a white dwarf, shape our understanding of the expansion of the universe with the use of… (more)

Bryngelson, Ginger

2012-01-01T23:59:59.000Z

280

The Carnegie Supernova Project: The Low-Redshift Survey  

E-Print Network [OSTI]

Supernovae are essential to understanding the chemical evolution of the Universe. Type Ia supernovae also provide the most powerful observational tool currently available for studying the expansion history of the Universe and the nature of dark energy. Our basic knowledge of supernovae comes from the study of their photometric and spectroscopic properties. However, the presently available data sets of optical and near-infrared light curves of supernovae are rather small and/or heterogeneous, and employ photometric systems that are poorly characterized. Similarly, there are relatively few supernovae whose spectral evolution has been well sampled, both in wavelength and phase, with precise spectrophotometric observations. The low-redshift portion of the Carnegie Supernova Project (CSP) seeks to remedy this situation by providing photometry and spectrophotometry of a large sample of supernovae taken on telescope/filter/detector systems that are well understood and well characterized. During a five-year program which began in September 2004, we expect to obtain high-precision u'g'r'i'BVYJHKs light curves and optical spectrophotometry for about 250 supernovae of all types. In this paper we provide a detailed description of the CSP survey observing and data reduction methodology. In addition, we present preliminary photometry and spectra obtained for a few representative supernovae during the first observing campaign.

Mario Hamuy; Gastón Folatelli; Nidia I. Morrell; Mark M. Phillips; Nicholas B. Suntzeff; S. E. Persson; Miguel Roth; Sergio Gonzalez; Wojtek Krzeminski; Carlos Contreras; Wendy L. Freedman; D. C. Murphy; Barry F. Madore; P. Wyatt; José Maza; Alexei V. Filippenko; Weidong Li; P. A. Pinto

2005-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Optical Spectra of Thermonuclear Supernovae in the Local and Distant Universe.  

E-Print Network [OSTI]

??This thesis is devoted to the study of optical spectra of thermonuclear supernovae, known as ``Type Ia'' supernovae (SN Ia). These violent stellar explosions, visible… (more)

Blondin, Stephane

2005-01-01T23:59:59.000Z

282

E-Print Network 3.0 - aspherical core-collapse supernovae Sample...  

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

supernovae: New challenges and perspectives 12;Outline Introduction... Gamma-ray bursts Nucleosynthesis, etc.. Up to now only SN1987A TAMA300 Core-collapse Supernovae...

283

Dark Matter Balls Help Supernovae to Explode  

E-Print Network [OSTI]

As a solution to the well-known problem that the shock wave potentially responsible for the explosion of a supernova actually tends to stall, we propose a new energy source arising from our model for dark matter. Our earlier model proposed that dark matter should consist of cm-large white dwarf-like objects kept together by a skin separating two different sorts of vacua. These dark matter balls or pearls will collect in the middle of any star throughout its lifetime. At some stage during the development of a supernova the balls will begin to take in neutrons and then other surrounding material. By passing into a ball nucleons fall through a potential of order 10 MeV, causing a severe production of heat - of order 10 foe for a solar mass of material eaten by the balls. The temperature in the iron core will thereby be raised, splitting up the iron into smaller nuclei. This provides a mechanism for reviving the shock wave when it arrives and making the supernova explosion really occur. The onset of the heating d...

Froggatt, Colin D

2015-01-01T23:59:59.000Z

284

SUPERNOVA EXPLOSIONS OF SUPER-ASYMPTOTIC GIANT BRANCH STARS: MULTICOLOR LIGHT CURVES OF ELECTRON-CAPTURE SUPERNOVAE  

SciTech Connect (OSTI)

An electron-capture supernova (ECSN) is a core-collapse supernova (CCSN) explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M{sub MS} {approx} 7-9.5 M{sub Sun }. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curve of a CCSN. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 Multiplication-Sign 10{sup 50} erg and the small {sup 56}Ni mass of 2.5 Multiplication-Sign 10{sup -3} M{sub Sun }, we perform a multi-group radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope masses and hydrogen abundances. We demonstrate that a shock breakout has a peak luminosity of L {approx} 2 Multiplication-Sign 10{sup 44} erg s{sup -1} and can evaporate circumstellar dust up to R {approx} 10{sup 17} cm for the case of carbon dust, that the plateau luminosity and plateau duration of ECSNe are L {approx} 10{sup 42} erg s{sup -1} and t {approx} 60-100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by {approx}4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by the spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires an ECSN model with a significantly low explosion energy of E {approx} 10{sup 48} erg.

Tominaga, Nozomu [Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501 (Japan); Blinnikov, Sergei I. [Institute for Theoretical and Experimental Physics (ITEP), Moscow 117218 (Russian Federation); Nomoto, Ken'ichi, E-mail: tominaga@konan-u.ac.jp, E-mail: Sergei.Blinnikov@itep.ru, E-mail: nomoto@astron.s.u-tokyo.ac.jp [Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)

2013-07-01T23:59:59.000Z

285

Real time cosmology - A direct measure of the expansion rate of the Universe  

E-Print Network [OSTI]

In recent years cosmology has undergone a revolution, with precise measurements of the microwave background radiation, large galaxy redshift surveys, and the discovery of the recent accelerated expansion of the Universe using observations of distant supernovae. In this light, the SKA enables us to do an ultimate test in cosmology by measuring the expansion rate of the Universe in real time. This can be done by a rather simple experiment of observing the neutral hydrogen (HI) signal of galaxies at two different epochs. The signal will encounter a change in frequency imprinted as the Universe expands over time and thus monitoring the drift in frequencies will provide a real time measure of the cosmic acceleration. Over a period of 12 years one would expected a frequency shift of the order of 0.1 Hz assuming a standard Lambda-CDM cosmology. Based on the sensitivity estimates of the SKA and the number counts of the expected HI galaxies, it is shown that the number counts are sufficiently high to compensate for th...

Klöckner, H -R; Martins, C; Raccanelli, A; Champion, D; Roy, A; Lobanov, A; Wagner, J; Keller, R

2015-01-01T23:59:59.000Z

286

Cosmographic bounds on the cosmological deceleration-acceleration transition redshift in $f(\\mathcal{R})$ gravity  

E-Print Network [OSTI]

We examine the observational viability of a class of $f(\\mathcal{R})$ gravity cosmological models. Particular attention is devoted to constraints from the recent observational determination of the redshift of the cosmological deceleration-acceleration transition. Making use of the fact that the Ricci scalar is a function of redshift $z$ in these models, $\\mathcal {R=R}(z)$, and so is $f(z)$, we use cosmography to relate a $f(z)$ test function evaluated at higher $z$ to late-time cosmographic bounds. First, we consider a model independent procedure to build up a numerical $f(z)$ by requiring that at $z=0$ the corresponding cosmological model reduces to standard $\\Lambda$CDM. We then infer late-time observational constraints on $f(z)$ in terms of bounds on the Taylor expansion cosmographic coefficients. In doing so we parameterize possible departures from the standard $\\Lambda$CDM model in terms of a two-parameter logarithmic correction. The physical meaning of the two parameters is also discussed in terms of the post Newtonian approximation. Second, we provide numerical estimates of the cosmographic series terms by using Type Ia supernova apparent magnitude data and Hubble parameter measurements. Finally, we use these estimates to bound the two parameters of the logarithmic correction. We find that the deceleration parameter in our model changes sign at a redshift consistent with what is observed.

Salvatore Capozziello; Omer Farooq; Orlando Luongo; Bharat Ratra

2014-03-06T23:59:59.000Z

287

Cosmological Analysis of Pilgrim Dark Energy in Loop Quantum Cosmology  

E-Print Network [OSTI]

The proposal of pilgrim dark energy is based on speculation that phantom-like dark energy (with strong enough resistive force) can prevent black hole formation in the universe. We explore this phenomenon in loop quantum cosmology framework by taking Hubble horizon as an infra-red cutoff in pilgrim dark energy. We evaluate the cosmological parameters such as Hubble, equation of state parameter, squared speed of sound and also cosmological planes like $\\omega_{\\vartheta}-\\omega'_{\\vartheta}$ and $r-s$ on the basis of pilgrim dark energy parameter ($u$) and interacting parameter ($d^2$). It is found that values of Hubble parameter lies in the range $74^{+0.005}_{-0.005}$. It is mentioned here that equation state parameter lies within the ranges $-1\\mp0.00005$ for $u=2, 1$ and $(-1.12,-1), (-5,-1)$ for $u=-1,-2$, respectively. Also, $\\omega_{\\vartheta}-\\omega'_{\\vartheta}$ planes provide $\\Lambda$CDM limit, freezing and thawing regions for all cases of $u$. It is also interesting to mention here that $\\omega_{\\va...

Jawad, Abdul

2015-01-01T23:59:59.000Z

288

STATISTICS GROUP  

E-Print Network [OSTI]

2 MOTIVATION Kyle Cranmer (NYU) CERN School HEP, Romania, Sept. 2011 What do these plots mean? 0 1 2 for Cosmology and Particle Physics CERN School HEP, Romania, Sept. 2011 The Likelihood Function A Poisson Kyle Cranmer): MARKED POISSON Kyle Cranmer (NYU) CERN School HEP, Romania, Sept. 2011 and use Monte

289

The Schwarzschild Static Cosmological Model  

E-Print Network [OSTI]

The present work describes an immersion in 5D of the interior Schwarzschild solution of the general relativity equations. The model theory is defined in the context of a flat 5D space time matter Minkowski model, using a Tolman like technique, which shows via Lorentz transformations that the solution is compatible with homogeneity and isotropy,thus obeying the cosmological principle. These properties permit one to consider the solution in terms of a cosmological model. In this model, the Universe may be treated as an idealized star with constant density and variable pressure, where each observer can be the center of the same. The observed redshift appears as a static gravitational effect which obeys the sufficiently verified and generally accepted square distance law. The Buchdahl stability theorem establishes a limit of distance observation with density dependence.

P. H. Pereyra

2009-04-16T23:59:59.000Z

290

Cosmology: a bird's eye view  

E-Print Network [OSTI]

In this essay we discuss the difference in views of the Universe as seen by two different observers. While one of the observers follows a geodesic congruence defined by the geometry of the cosmological model, the other observer follows the fluid flow lines of a perfect fluid with a linear equation of state. We point out that the information these observers collect regarding the state of the Universe can be radically different; while one observes a non-inflating ever-expanding ever-lasting universe, the other observer can experience a dynamical behaviour reminiscent to that of quintessence or even that of a phantom cosmology leading to a 'big rip' singularity within finite time (but without the need for exotic forms of matter).

Alan A. Coley; Sigbjorn Hervik; Woei Chet Lim

2006-05-15T23:59:59.000Z

291

Cosmology, Thermodynamics and Matter Creation  

E-Print Network [OSTI]

Several approaches to the matter creation problem in the context of cosmological models are summarily reviewed. A covariant formulation of the general relativistic imperfect simple fluid endowed with a process of matter creation is presented. By considering the standard big bang model, it is shown how the recent results of Prigogine et alii \\cite{1} can be recovered and, at the same time their limits of validity are explicited.

J. A. S. Lima; M. O. Calvao; I. Waga

2007-08-24T23:59:59.000Z

292

Disformal transformation of cosmological perturbations  

E-Print Network [OSTI]

We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar-tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar-tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (non)conservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame.

Masato Minamitsuji

2014-09-04T23:59:59.000Z

293

Emergent cosmological constant from colliding electromagnetic waves  

E-Print Network [OSTI]

In this study we advocate the view that the cosmological constant is of electromagnetic (em) origin, which can be generated from the collision of em shock waves coupled with gravitational shock waves. The wave profiles that participate in the collision have different amplitudes. It is shown that, circular polarization with equal amplitude waves does not generate cosmological constant. We also prove that the generation of the cosmological constant is related to the linear polarization. The addition of cross polarization generates no cosmological constant. Depending on the value of the wave amplitudes, the generated cosmological constant can be positive or negative. We show additionally that, the collision of nonlinear em waves in a particular class of Born-Infeld theory also yields a cosmological constant.

M. Halilsoy; S. Habib Mazharimousavi; O. Gurtug

2014-10-15T23:59:59.000Z

294

String Gas Cosmology and Non-Gaussianities  

E-Print Network [OSTI]

Recently it has been shown that string gas cosmology, an alternative model of the very early universe which does not involve a period of cosmological inflation, can give rise to an almost scale invariant spectrum of metric perturbations. Here we calculate the non-Gaussianities of the spectrum of cosmological fluctuations in string gas cosmology, and find that these non-Gaussianities depend linearly on the wave number and that their amplitude depends sensitively on the string scale. If the string scale is at the TeV scale, string gas cosmology could lead to observable non-Gaussianities, if it is close to the Planck scale, then the non-Gaussianities on current cosmological scales are negligible.

Bin Chen; Yi Wang; Wei Xue; Robert Brandenberger

2008-03-05T23:59:59.000Z

295

Synthetic Spectrum Methods for Three-Dimensional Supernova Models  

E-Print Network [OSTI]

Current observations stimulate the production of fully three-dimensional explosion models, which in turn motivates three-dimensional spectrum synthesis for supernova atmospheres. We briefly discuss techniques adapted to address the latter problem, and consider some fundamentals of line formation in supernovae without recourse to spherical symmetry. Direct and detailed extensions of the technique are discussed, and future work is outlined.

R. C. Thomas

2003-10-21T23:59:59.000Z

296

The Berry phase in inflationary cosmology  

E-Print Network [OSTI]

We derive an analogue of the Berry phase associated with inflationary cosmological perturbations of quantum mechanical origin by obtaining the corresponding wavefunction. We have further shown that cosmological Berry phase can be completely envisioned through the observable parameters, viz. spectral indices. Finally, physical significance of this phase is discussed from the point of view of theoretical and observational aspects with some possible consequences of this quantity in inflationary cosmology.

Barun Kumar Pal; Supratik Pal; B. Basu

2013-04-25T23:59:59.000Z

297

Diversity of Type Ia Supernovae Imprinted in Chemical Abundances  

E-Print Network [OSTI]

A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit a SN Ia-like elemental feature including a very low [Mg/Fe] (~-1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr,Mn,Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth, and gives a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nice...

Tsujimoto, Takuji

2012-01-01T23:59:59.000Z

298

First trillion particle cosmological simulation completed  

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

trillion particle cosmological simulation completed A team of astrophysicists and computer scientists has created high-resolution cyber images of our cosmos. December 3, 2014...

299

Landscape Predictions from Cosmological Vacuum Selection  

E-Print Network [OSTI]

In BP models with hundreds of fluxes, we compute the effects of cosmological dynamics on the probability distribution of landscape vacua. Starting from generic initial conditions, we find that most fluxes are dynamically driven into a different and much narrower range of values than expected from landscape statistics alone. Hence, cosmological evolution will access only a tiny fraction of the vacua with small cosmological constant. This leads to a host of sharp predictions. Unlike other approaches to eternal inflation, the holographic measure employed here does not lead to "staggering", an excessive spread of probabilities that would doom the string landscape as a solution to the cosmological constant problem.

Raphael Bousso; I-Sheng Yang

2007-05-09T23:59:59.000Z

300

Variable cosmological term - geometry and physics  

E-Print Network [OSTI]

We describe the dynamics of a cosmological term in the spherically symmetric case by an r-dependent second rank symmetric tensor \\Lambda_{\\mu\

Irina Dymnikova

2000-10-04T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Diffuse supernova neutrinos: oscillation effects, stellar cooling and progenitor mass dependence  

SciTech Connect (OSTI)

We estimate the diffuse supernova neutrino background (DSNB) using the recent progenitor-dependent, long-term supernova simulations from the Basel group and including neutrino oscillations at several post-bounce times. Assuming multi-angle matter suppression of collective effects during the accretion phase, we find that oscillation effects are dominated by the matter-driven MSW resonances, while neutrino-neutrino collective effects contribute at the 5–10% level. The impact of the neutrino mass hierarchy, of the time-dependent neutrino spectra and of the diverse progenitor star population is 10% or less, small compared to the uncertainty of at least 25% of the normalization of the supernova rate. Therefore, assuming that the sign of the neutrino mass hierarchy will be determined within the next decade, the future detection of the DSNB will deliver approximate information on the MSW-oscillated neutrino spectra. With a reliable model for neutrino emission, its detection will be a powerful instrument to provide complementary information on the star formation rate and for learning about stellar physics.

Lunardini, Cecilia [Arizona State University, Tempe, AZ, 85287-1504 (United States); Tamborra, Irene, E-mail: Cecilia.Lunardini@asu.edu, E-mail: tamborra@mpp.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6, 80805 München (Germany)

2012-07-01T23:59:59.000Z

302

Flavor Changing Supersymmetry Interactions in a Supernova  

E-Print Network [OSTI]

We consider for the first time R-parity violating interactions of the Minimal Standard Supersymmetric Model involving neutrinos and quarks (``flavor changing neutral currents'', FCNC's) in the infall stage of stellar collapse. Our considerations extend to other kinds of flavor changing neutrino reactions as well. We examine non-forward neutrino scattering processes on heavy nuclei and free nucleons in the supernova core. This investigation has led to four principal original discoveries/products: (1) first calculation of neutrino flavor changing cross sections for spin one half (e.g. free nucleon) and spin zero nuclear targets; (2) discovery of nuclear mass number squared (A squared) coherent amplification of neutrino-quark FCNC's; (3) analysis of FCNC-induced alteration of electron capture and weak/nuclear equilibrium in the collapsing core; and (4) generalization of the calculated cross sections (mentioned in 1) for the case of hot heavy nuclei to be used in collapse/supernova and neutrino transport simulations. The scattering processes that we consider allow electron neutrinos to change flavor during core collapse, thereby opening holes in the electron neutrino sea, which allows electron capture to proceed and results in a lower core electron fraction. A lower electron fraction implies a lower homologous core mass, a lower shock energy, and a greater nuclear photo-disintegration burden for the shock. In addition, unlike the standard supernova model, the core now could have net muon and/or tau lepton numbers. These effects could be significant even for supersymmetric couplings below current experimental bounds.

Philip S. Amanik; George M. Fuller; Benjamin Grinstein

2005-10-14T23:59:59.000Z

303

Pair-Production Supernovae: Theory and Observation  

E-Print Network [OSTI]

I review the physical properties of pair-production supernovae (PPSNe) as well as the prospects for them to be constrained observationally. In very massive (140-260 solar mass) stars, much of the pressure support comes from the radiation field, meaning that they are loosely bound, with an adiabatic coefficient that is close to the minimum stable value. Near the end of C/O burning, the central temperature increases to the point that photons begin to be converted into electron-positron pairs, softening gamma below this critical value. The result is a runaway collapse, followed by explosive burning that completely obliterates the star. While these explosions can be up to 100 times more energetic that core collapse and Type Ia supernovae, their peak luminosities are only slightly greater. However, due both to copious Ni-56 production and hydrogen recombination, they are brighter much longer, and remain observable for ~ 1 year. Since metal enrichment is a local process, PPSNe should occur in pockets of metal-free gas over a broad range of redshifts, greatly enhancing their detectability, and distributing their nucleosyntehtic products about the Milky Way. This means that measurements of the abundances of metal-free stars should be thought of as directly constraining these objects. It also means that ongoing supernova searches, already provide weak constraints for PPSN models. A survey with the NIRCam instrument on JWST, on the other hand, would be able to extend these limits to z ~ 10. Observing a 0.3 deg^2 patch of sky for one week per year for three consecutive years, such a program would either detect or rule out the existence of these remarkable objects.

Evan Scannapieco

2006-09-07T23:59:59.000Z

304

Cosmographic Hubble fits to the supernova data  

E-Print Network [OSTI]

The Hubble relation between distance and redshift is a purely cosmographic relation that depends only on the symmetries of a FLRW spacetime, but does not intrinsically make any dynamical assumptions. This suggests that it should be possible to estimate the parameters defining the Hubble relation without making any dynamical assumptions. To test this idea, we perform a number of inter-related cosmographic fits to the legacy05 and gold06 supernova datasets. Based on this supernova data, the "preponderance of evidence" certainly suggests an accelerating universe. However we would argue that (unless one uses additional dynamical and observational information) this conclusion is not currently supported "beyond reasonable doubt". As part of the analysis we develop two particularly transparent graphical representations of the redshift-distance relation -- representations in which acceleration versus deceleration reduces to the question of whether the relevant graph slopes up or down. Turning to the details of the cosmographic fits, three issues in particular concern us: First, the fitted value for the deceleration parameter changes significantly depending on whether one performs a chi^2 fit to the luminosity distance, proper motion distance or other suitable distance surrogate. Second, the fitted value for the deceleration parameter changes significantly depending on whether one uses the traditional redshift variable z, or what we shall argue is on theoretical grounds an improved parameterization y=z/(1+z). Third, the published estimates for systematic uncertainties are sufficiently large that they certainly impact on, and to a large extent undermine, the usual purely statistical tests of significance. We conclude that the supernova data should be treated with some caution.

Celine Cattoen; Matt Visser

2008-09-03T23:59:59.000Z

305

The supernova that destroyed a galaxy  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layered NbS2 andThe MolecularPlaceTheofThebatteryTheThe supernova

306

Neutrino signal of supernova shock wave propagation:MSW distortion of the spectra and neucleosynthesis  

E-Print Network [OSTI]

Neutrino signal of supernova shock wave propagation:MSW distortion of the spectra and neucleosynthesis

Kawagoe, S; Sumiyoshi, K; Yamada, H; Kajino, T

2006-01-01T23:59:59.000Z

307

Supersymmetric quantum solution for FRW cosmological model with matter  

E-Print Network [OSTI]

Using technique of supersymmetric quantum mechanics we present new cosmological quantum solution, in the regime for FRW cosmological model using a barotropic perfect fluid as matter field.

J. Socorro

2001-08-09T23:59:59.000Z

308

Measurement of Omega_m, Omega_Lambda from a blind analysis of Type Ia supernovae with CMAGIC: Using color information to verify the acceleration of the Universe  

E-Print Network [OSTI]

analysis of Type Ia supernovae with CMAGIC: Using colorof 21 high redshift supernovae using a new technique (lightcurves of Type Ia supernovae, ?rst introduced in Wang

2006-01-01T23:59:59.000Z

309

Mapping the Heavens: Probing Cosmology with the Sloan Digital Sky Survey  

SciTech Connect (OSTI)

This talk will provide an overview of results from the on-going Sloan Digital Sky Survey (SDSS), the most ambitious mapping of the Universe yet undertaken, focusing on those with implications for cosmology. It will include a virtual fly-through of the survey that reveals the 3-dimensional large-scale structure of the galaxy distribution. Recent measurements of this large-scale structure, in combination with observations of the cosmic microwave background, have provided independent evidence for a Universe dominated by dark matter and dark energy as well as insights into how galaxies and larger-scale structures formed. I will also describe early results from the SDSS Supernova Survey, which aims to provide more precise constraints on the nature of dark energy. Future planned surveys from the ground and from space will build on these foundations to probe the history of the cosmic expansion--and thereby the dark energy--with even greater precision.

Frieman, Josh (University of Chicago) [University of Chicago

2006-12-04T23:59:59.000Z

310

Cosmological constraints on a dark energy model with a non-linear scalar field  

E-Print Network [OSTI]

In the present work we study a dark energy model in which a non-linear scalar field (tachyon) with a Born-Infeld type of action is responsible for the observed cosmic acceleration. The potential of the tachyon is well-motivated since it comes from open string theory and the model is subjected to various cosmological constraints with data coming from supernovae as well as from microwave background radiation. Our analysis shows that in the particular model under study the tachyon can be an excellent candidate for dark energy in the universe, as the model agrees with a series of observational data and for a wide range of the parameters of the model.

G. Panotopoulos

2006-06-16T23:59:59.000Z

311

Distance-Redshift in Inhomogeneous $Omega_0=1$ Friedmann-Lemaitre-Robertson-Walker Cosmology  

E-Print Network [OSTI]

Distance--redshift relations are given in terms of associated Legendre functions for partially filled beam observations inspatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmologies. These models are dynamically pressure-free, flat FLRW on large scales but, due to mass inhomogeneities, differ in their optical properties. The partially filled beam area-redshift equation is a Lame$^{\\prime}$ equation for arbitrary FLRW and is shown to simplify to the associated Legendre equation for the spatially flat, i.e. $\\Omega_0=1$ case. We fit these new analytic Hubble curves to recent supernovae (SNe) data in an attempt to determine both the mass parameter $\\Omega_m$ and the beam filling parameter $\

R. Kantowski; R. C. Thomas

2001-06-18T23:59:59.000Z

312

Quasilocal Energy in FRW Cosmology  

E-Print Network [OSTI]

This paper presents a calculation of the quasilocal energy of a generic FRW model of the universe. The results have the correct behavior in the small-sphere limit and vanish for the empty Milne universe. Higher order corrections are found when comparing these results to classical calculations of cosmological energy. This case is different from others in the literature chiefly in that it involves a non-stationary spacetime. This fact can be used to differentiate between the various formulations of quasilocal energy. In particular, the formulation due to Brown and York is compared to that of Epp. Only one of these is seen to have the correct classical limit.

M. M. Afshar

2009-10-03T23:59:59.000Z

313

Surface brightness in plasma-redshift cosmology  

E-Print Network [OSTI]

In 2001 Lori M. Lubin and Allan Sandage, using big-bang cosmology for interpreting the data, found the surface brightness of galaxies to be inversely proportional to about the third power of (1+z), while the contemporary big-bang cosmology predicts that the surface brightness is inversely proportional to the fourth power of (1+z). In contrast, these surface brightness observations are in agreement with the predictions of the plasma-redshift cosmology. Lubin and Sandage (2001) and Barden et al. (2005), who surmised the big-bang expansion, interpreted the observations to indicate that the diameters of galaxies are inversely proportional to (1+z). In contrast, when assuming plasma-redshift cosmology, the diameters of galaxies are observed to be constant independent of redshift and any expansion. Lubin and Sandage (2001) and Barden et al. (2005), when using big-bang cosmology, observed the average absolute magnitude of galaxies to decrease with redshift; while in plasma redshift cosmology it is a constant. Lubin and Sandage and Barden et al. suggested that a coherent evolution could explain the discrepancy between the observed relations and those predicted in the big-bang cosmology. We have failed to find support for this explanation. We consider the observed relations between the redshift and the surface-brightness, the galaxy diameter, and the absolute magnitude to be robust confirmations of plasma-redshift cosmology.

Ari Brynjolfsson

2006-05-31T23:59:59.000Z

314

A Time-dependent Cosmological Constant Phenomenology  

E-Print Network [OSTI]

We construct a cosmological toy model in which a step-function ``cosmological constant'' is taken into consideration beside ordinary matter. We assume that $\\Lambda$ takes two values depending on the epoch, and matter goes from a radiation dominated era to a dust dominated era. The model is exactly solvable and it can be compared with recent observations.

Salvatore Capozziello; Ruggiero de Ritis; Alma Angela Marino

1996-05-29T23:59:59.000Z

315

Planck Scale Cosmology in Resummed Quantum Gravity  

E-Print Network [OSTI]

We show that, by using resummation techniques based on the extension of the methods of Yennie, Frautschi and Suura to Feynman's formulation of Einstein's theory, we get quantum field theoretic predictions for the UV fixed-point values of the dimensionless gravitational and cosmological constants. Connections to the phenomenological asymptotic safety analysis of Planck scale cosmology by Bonanno and Reuter are discussed.

B. F. L. Ward

2008-08-23T23:59:59.000Z

316

Planck Scale Cosmology and Resummed Quantum Gravity  

E-Print Network [OSTI]

We show that, by using amplitude-based resummation techniques for Feynman's formulation of Einstein's theory, we get quantum field theoretic 'first principles' predictions for the UV fixed-point values of the dimensionless gravitational and cosmological constants. Connections to the phenomenological asymptotic safety analysis of Planck scale cosmology by Bonanno and Reuter are discussed.

B. F. L. Ward

2009-10-13T23:59:59.000Z

317

Incompatibility of a comoving Ly-alpha forest with supernova-Ia luminosity distances  

E-Print Network [OSTI]

Recently Perlmutter et al. suggested a positive value of Einstein's cosmological constant Lambda on the basis of luminosity distances from type-Ia supernovae. However, Lambda world models had earlier been proposed by Hoell & Priester and Liebscher et al. on the basis of quasar absorption-line data. Employing more general repulsive fluids ("dark energy") encompassing the Lambda component we quantitatively compare both approaches with each other. Fitting the SN-data by a minimum-component model consisting of dark energy + dust yields a closed universe with a large amount of dust exceeding the baryonic content constrained by big-bang nucleosynthesis. The nature of the dark energy is hardly constrained. Only when enforcing a flat universe there is a clear tendency to a dark-energy Lambda fluid and the `canonical' value Omega_M = 0.3 for dust. Conversely, fitting the quasar-data by a minimum-component model yields a sharply defined, slightly closed model with a low dust density ruling out significant pressureless dark matter. The dark-energy component obtains an equation-of-state P = -0.96 epsilon close to that of a Lambda-fluid. Omega_M = 0.3 or a precisely flat spatial geometry are inconsistent with minimum-component models. It is found that quasar and supernova data sets cannot be reconciled with each other via (repulsive ideal fluid+dust+radiation)-world models. Compatibility could be reached by drastic expansion of the parameter space with at least two exotic fluids added to dust and radiation as world constituents. If considering such solutions as far-fetched one has to conclude that the quasar absorption line and the SN-Ia constraints are incompatible.

Jens Thomas; Hartmut Schulz

2001-03-18T23:59:59.000Z

318

Could there be a hole in type Ia supernovae?  

SciTech Connect (OSTI)

In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity.

Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

2004-04-23T23:59:59.000Z

319

COSMOLOGICAL SIMULATIONS OF INTERGALACTIC MEDIUM EVOLUTION. I. TEST OF THE SUBGRID CHEMICAL ENRICHMENT MODEL  

SciTech Connect (OSTI)

We present a one-zone galactic chemical enrichment model that takes into account the contribution of stellar winds from massive stars under the effect of rotation, Type II supernovae, hypernovae, stellar winds from low- and intermediate-mass stars, and Type Ia supernovae. This enrichment model will be implemented in a galactic model designed to be used as a subgrid treatment for galaxy evolution and outflow generation in large-scale cosmological simulations, in order to study the evolution of the intergalactic medium. We test our enrichment prescription by comparing its predictions with the metallicity distribution function and the abundance patterns of 14 chemical elements observed in the Milky Way stars. To do so, we combine the effect of many stellar populations created from the star formation history of the Galaxy in the solar neighborhood. For each stellar population, we keep track of its specific mass, initial metallicity, and age. We follow the time evolution of every population in order to respect the time delay between the various stellar phases. Our model is able to reproduce the observed abundances of C, O, Na, Mg, Al, S, and Ca. For Si, Cr, Mn, Ni, Cu, and Zn, the fits are still reasonable, but improvements are needed. We marginally reproduce the nitrogen abundance in very low metallicity stars. Overall, our results are consistent with the predicted abundance ratios seen in previous studies of the enrichment history of the Milky Way. We have demonstrated that our semi-analytic one-zone model, which cannot deal with spatial information such as the metallicity gradient, can nevertheless successfully reproduce the global Galactic enrichment evolution obtained by more complex models, at a fraction of the computational cost. This model is therefore suitable for a subgrid treatment of chemical enrichment in large-scale cosmological simulations.

Côté, Benoit; Martel, Hugo; Drissen, Laurent [Département de physique, de Génie Physique et d'Optique, Université Laval, Québec, QC G1V 0A6 (Canada)

2013-11-10T23:59:59.000Z

320

Vacuum energy and cosmological evolution  

E-Print Network [OSTI]

An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary description of a true dynamical vacuum energy variable that is evolving from the inflationary epoch to the present day. We can compare the evolving vacuum energy with a Casimir device where the parallel plates slowly move apart ("expand"). The total vacuum energy density cannot be measured, only the effect associated to the presence of the plates, and then also their increasing separation with time. In the universe there is a nonvanishing spacetime curvature $R$ as compared to Minkowskian spacetime that is changing with the expansion. The vacuum energy density must change accordingly, and we naturally expect $\\delta\\Lambda\\sim R\\sim H^2$. A class of dynamical vacuum models that trace such rate of change can be constructed. They are compatible with the current cosmological data, and conveniently extended can account for the complete cosmic evolution from the inflationary epoch till the present days. These models are very close to the $\\Lambda$CDM model for the late universe, but very different from it at the early times. Traces of the inherent vacuum dynamics could be detectable in our recent past.

Joan Sola

2014-03-03T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Relaxing a large cosmological constant  

E-Print Network [OSTI]

The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times, it has been rephrased as the dark energy problem in order to encompass a wider spectrum of possibilities. It is, in any case, a polyhedric puzzle with many faces, including the cosmic coincidence problem, i.e. why the density of matter is presently so close to the CC density. However, the oldest, toughest and most intriguing face of this polyhedron is the big CC problem, namely why the measured value of the CC at present is so small as compared to any typical density scale existing in high energy physics, especially taking into account the many phase transitions that our Universe has undergone since the early times, including inflation. In this letter, we propose to extend the field equations of General Relativity by including a class of invariant terms that automatically relax the value of the CC irrespective of the initial size of the vacuum energy in the early epochs. We show that, at late times, the Universe enters an eternal de Sitter stage mimicking a tiny positive cosmological constant. Thus, these models could solve the big CC problem and have also a bearing on the cosmic coincidence problem. Remarkably, they mimic the LCDM model to a large extent, but they still leave some characteristic imprints that should be testable in the next generation of experiments.

Florian Bauer; Joan Sola; Hrvoje Stefancic

2009-07-23T23:59:59.000Z

322

Statistical Mechanics and Quantum Cosmology  

E-Print Network [OSTI]

Statistical mechanical concepts and processes such as decoherence, correlation, and dissipation can prove to be of basic importance to understanding some fundamental issues of quantum cosmology and theoretical physics such as the choice of initial states, quantum to classical transition and the emergence of time. Here we summarize our effort in 1) constructing a unified theoretical framework using techniques in interacting quantum field theory such as influence functional and coarse-grained effective action to discuss the interplay of noise, fluctuation, dissipation and decoherence; and 2) illustrating how these concepts when applied to quantum cosmology can alter the conventional views on some basic issues. Two questions we address are 1) the validity of minisuperspace truncation, which is usually assumed without proof in most discussions, and 2) the relevance of specific initial conditions, which is the prevailing view of the past decade. We also mention how some current ideas in chaotic dynamics, dissipative collective dynamics and complexity can alter our view of the quantum nature of the universe.

B. L. Hu

1995-11-29T23:59:59.000Z

323

Analogue models for FRW cosmologies  

E-Print Network [OSTI]

It is by now well known that various condensed matter systems may be used to mimic many of the kinematic aspects of general relativity, and in particular of curved-spacetime quantum field theory. In this essay we will take a look at what would be needed to mimic a cosmological spacetime -- to be precise a spatially flat FRW cosmology -- in one of these analogue models. In order to do this one needs to build and control suitable time dependent systems. We discuss here two quite different ways to achieve this goal. One might rely on an explosion, physically mimicking the big bang by an outflow of whatever medium is being used to carry the excitations of the analogue model, but this idea appears to encounter dynamical problems in practice. More subtly, one can avoid the need for any actual physical motion (and avoid the dynamical problems) by instead adjusting the propagation speed of the excitations of the analogue model. We shall focus on this more promising route and discuss its practicality.

Carlos Barcelo; Stefano Liberati; Matt Visser

2003-05-16T23:59:59.000Z

324

Particle acceleration at supernova shocks in young stellar clusters  

E-Print Network [OSTI]

We briefly discuss models of energetic particle acceleration by supernova shock in active starforming regions at different stages of their evolution. Strong shocks may strongly amplify magnetic fields due to cosmic ray driven instabilities. We discuss the magnetic field amplification emphasizing the role of the long-wavelength instabilities. Supernova shock propagating in the vicinity of a powerful stellar wind in a young stellar cluster is argued to increase the maximal CR energies at a given evolution stage of supernova remnant (SNR) and can convert a sizeable fraction of the kinetic energy release into energetic particles.

Bykov, A M; Osipov, S M

2011-01-01T23:59:59.000Z

325

Thermonuclear supernova explosions and their remnants: the case of Tycho  

E-Print Network [OSTI]

We propose to use the thermal X-ray emission from young supernova remnants (SNRs) originated in Type Ia supernovae (SNe) to extract relevant information concerning the explosion mechanism. We focus on the differences between numerical 1D and 3D explosion calculations, and the impact that these differences could have on young SNRs. We use the remnant of the Tycho supernova (SN 1572) as a test case to compare with our predictions, discussing the observational features that allow to accept or discard a given model.

Carles Badenes; Eduardo Bravo; Kazimierz J. Borkowski

2003-09-03T23:59:59.000Z

326

The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-masswhite dwarf star  

SciTech Connect (OSTI)

The acceleration of the expansion of the universe, and theneed for Dark Energy, were inferred from the observations of Type Iasupernovae (SNe Ia) 1;2. There is consensus that SNeIa are thermonuclearexplosions that destroy carbon-oxygen white dwarf stars that accretematter from a companion star3, although the nature of this companionremains uncertain. SNe Ia are thought to be reliable distance indicatorsbecause they have a standard amount of fuel and a uniform trigger theyare predicted to explode when the mass of the white dwarf nears theChandrasekhar mass 4 - 1.4 solar masses. Here we show that the highredshift supernova SNLS-03D3bb has an exceptionally high luminosity andlow kinetic energy that both imply a super-Chandrasekhar mass progenitor.Super-Chandrasekhar mass SNeIa shouldpreferentially occur in a youngstellar population, so this may provide an explanation for the observedtrend that overluminous SNe Ia only occur in young environments5;6. Sincethis supernova does not obey the relations that allow them to becalibrated as standard candles, and since no counterparts have been foundat low redshift, future cosmology studies will have to considercontamination from such events.

Howell, D.Andrew; Sullivan, Mark; Nugent, Peter E.; Ellis,Richard S.; Conley, Alexander J.; Le Borgne, Damien; Carlberg, RaymondG.; Guy, Julien; Balam, David; Basa, Stephane; Fouchez, Dominique; Hook,Isobel M.; Hsiao, Eric Y.; Neill, James D.; Pain, Reynald; Perrett,Kathryn M.; Pritchet, Christopher J.

2006-02-01T23:59:59.000Z

327

CARBON DEFLAGRATION IN TYPE Ia SUPERNOVA. I. CENTRALLY IGNITED MODELS  

SciTech Connect (OSTI)

A leading model for Type Ia supernovae (SNe Ia) begins with a white dwarf near the Chandrasekhar mass that ignites a degenerate thermonuclear runaway close to its center and explodes. In a series of papers, we shall explore the consequences of ignition at several locations within such dwarfs. Here we assume central ignition, which has been explored before, but is worth revisiting, if only to validate those previous studies and to further elucidate the relevant physics for future work. A perturbed sphere of hot iron ash with a radius of {approx}100 km is initialized at the middle of the star. The subsequent explosion is followed in several simulations using a thickened flame model in which the flame speed is either fixed-within the range expected from turbulent combustion-or based on the local turbulent intensity. Global results, including the explosion energy and bulk nucleosynthesis (e.g., {sup 56}Ni of 0.48-0.56 M{sub Sun }) turn out to be insensitive to this speed. In all completed runs, the energy released by the nuclear burning is adequate to unbind the star, but not enough to give the energy and brightness of typical SNe Ia. As found previously, the chemical stratification observed in typical events is not reproduced. These models produce a large amount of unburned carbon and oxygen in central low velocity regions, which is inconsistent with spectroscopic observations, and the intermediate mass elements and iron group elements are strongly mixed during the explosion.

Ma, H.; Woosley, S. E.; Malone, C. M. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Almgren, A.; Bell, J. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Lab, Berkeley, CA 94720 (United States)

2013-07-01T23:59:59.000Z

328

Numerical simulations of super-luminous supernovae of type IIn  

E-Print Network [OSTI]

We present numerical simulations that include 1-D Eulerian multi-group radiation-hydrodynamics, 1-D non-LTE radiative transfer, and 2-D polarised radiative transfer for super-luminous interacting supernovae (SNe). Our reference model is a ~10Msun inner shell with 10^51erg ramming into a ~3Msun cold outer shell (the circumstellar-medium, or CSM) that extends from 10^15cm to 2x10^16cm and moves at 100km/s. We discuss the light curve evolution, which cannot be captured adequately with a grey approach. In these interactions, the shock-crossing time through the optically-thick CSM is much longer than the photon diffusion time. Radiation is thus continuously leaking from the shock through the CSM, in disagreement with the shell-shocked model that is often invoked. Our spectra redden with time, with a peak distribution in the near-UV during the first month gradually shifting to the optical range over the following year. Initially Balmer lines exhibit a narrow line core and the broad line wings that are characteristi...

Dessart, Luc; Hillier, D John

2015-01-01T23:59:59.000Z

329

INTERPLAY OF NEUTRINO OPACITIES IN CORE-COLLAPSE SUPERNOVA SIMULATIONS  

SciTech Connect (OSTI)

We have conducted a series of numerical experiments using spherically symmetric, general relativistic, neutrino radiation hydrodynamics with the code Agile-BOLTZTRAN to examine the effects of modern neutrino opacities on the development of supernova simulations. We test the effects of opacities by removing opacities or by undoing opacity improvements for individual opacities and groups of opacities. We find that improvements to electron capture (EC) on nuclei, namely EC on an ensemble of nuclei using modern nuclear structure models rather than the simpler independent-particle approximation (IPA) for EC on a mean nucleus, plays the most important role during core collapse of all tested neutrino opacities. Low-energy neutrinos emitted by modern nuclear EC preferentially escape during collapse without the energy downscattering on electrons required to enhance neutrino escape and deleptonization for the models with IPA nuclear EC. During shock breakout the primary influence on the emergent neutrinos arises from non-isoenergetic scattering (NIS) on electrons. For the accretion phase, NIS on free nucleons and pair emission by e {sup +} e {sup -} annihilation have the largest impact on the neutrino emission and shock evolution. Other opacities evaluated, including nucleon-nucleon bremsstrahlung and especially neutrino-positron scattering, have little measurable impact on neutrino emission or shock dynamics. Modern treatments of nuclear EC, e {sup +} e {sup -}-annihilation pair emission, and NIS on electrons and free nucleons are critical elements of core-collapse simulations of all dimensionality.

Lentz, Eric J. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Mezzacappa, Anthony; Hix, W. Raphael [Physics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6354 (United States); Messer, O. E. Bronson [National Center for Computational Sciences, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6164 (United States); Bruenn, Stephen W., E-mail: elentz@utk.edu [Department of Physics, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991 (United States)

2012-11-20T23:59:59.000Z

330

Interplay of Neutrino Opacities in Core-collapse Supernova Simulations  

SciTech Connect (OSTI)

We have conducted a series of numerical experiments using spherically symmetric, general relativistic, neutrino radiation hydrodynamics with the code Agile-BOLTZTRAN to examine the effects of including, and improving, the calculation of neutrino opacities on the development of supernova simulations by removing, or replacing, each opacity individually, or removing opacities in groups. We find that during core collapse improvements to electron capture (EC) on nuclei, namely EC on an ensemble of nuclei based on the hybrid model, relative to the simpler independent-particle approximation (IPA) for a mean nucleus, plays the most important role of all tested neutrino opacities. Low-energy neutrinos emitted by nuclear EC preferentially escape during collapse leading to larger deleptonization of the collapsing core, without the energy downscattering via non-isoenergetic scattering (NIS) on electrons required for the models with IPA nuclear EC. During shock breakout the primary influence on the emergent neutrinos arises from NIS on electrons. For the accretion phase NIS on free nucleons and pair emission by $e^+e^-$-annihilation have the largest impact on the neutrino emission and shock evolution. Other opacities evaluated including nucleon-nucleon bremsstrahlung and especially neutrino-positron scattering have little measurable impact on neutrino emission or shock dynamics. Modern treatments of nuclear electron capture, $e^+e^-$-annihilation pair emission, and non-isoenergetic scattering on electrons and free nucleons are critical elements of core-collapse simulations of all dimensionality.

Lentz, Eric J [ORNL; Mezzacappa, Anthony [ORNL; Messer, Bronson [ORNL; Hix, William Raphael [ORNL; Bruenn, S. W. [Florida Atlantic University

2012-01-01T23:59:59.000Z

331

Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054  

SciTech Connect (OSTI)

An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M{sub Ms} ? 7 - 9.5M{sub ?}. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 10{sup 50} erg and the small {sup 56}Ni mass of 2.5 × 10{sup ?3} M{sub ?}, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ? 2 × 10{sup 44} erg s{sup ?1} and can evaporate circumstellar dust up to R ? 10{sup 17} cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ? 10{sup 42} erg s{sup ?1} and {sup t} ? 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ? 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ? 10{sup 48} erg.

Nomoto, Ken'ichi [Kavli Institute for Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Tominaga, Nozomu [Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501, Japan and Kavli Institute for Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Blinnikov, Sergei I. [Institute for Theoretical and Experimental Physics (ITEP), Moscow 117218, Russia and Kavli Institute for Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)

2014-05-02T23:59:59.000Z

332

Are Models for Core-Collapse Supernova Progenitors Consistent with the Properties of Supernova Remnants?  

E-Print Network [OSTI]

The recent discovery that the Fe-K line luminosities and energy centroids observed in nearby SNRs are a strong discriminant of both progenitor type and circumstellar environment has implications for our understanding of supernova progenitor evolution. Using models for the chemical composition of core-collapse supernova ejecta, we model the dynamics and thermal X-ray emission from shocked ejecta and circumstellar material, modeled as an $r^{-2}$ wind, to ages of 3000 years. We compare the X-ray spectra expected from these models to observations made with the Suzaku satellite. We also model the dynamics and X-ray emission from Type Ia progenitor models. We find a clear distinction in Fe-K line energy centroid between core-collapse and Type Ia models. The core-collapse supernova models predict higher Fe-K line centroid energies than the Type Ia models, in agreement with observations. We argue that the higher line centroids are a consequence of the increased densities found in the circumstellar environment create...

Patnaude, Daniel J; Slane, Patrick O; Badenes, Carles; Heger, Alexander; Ellison, Donald C; Nagataki, Shigehiro

2015-01-01T23:59:59.000Z

333

Closest Type Ia Supernova in Decades Solves a Cosmic Mystery  

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

PTF 11kly as it appeared in the nearby M101 galaxy. (Images: Peter Nugent) Type Ia supernovae (SN Ia's) are the extraordinarily bright and remarkably similar "standard candles"...

334

A Critique of Core-Collapse Supernova Theory Circa 1997  

E-Print Network [OSTI]

There has been a new infusion of ideas in the study of the mechanism and early character of core--collapse supernovae. However, despite recent conceptual and computational progress, fundamental questions remain. Some are summarize herein.

Burrows, A

1998-01-01T23:59:59.000Z

335

A Critique of Core--Collapse Supernova Theory Circa 1997  

E-Print Network [OSTI]

There has been a new infusion of ideas in the study of the mechanism and early character of core--collapse supernovae. However, despite recent conceptual and computational progress, fundamental questions remain. Some are summarize herein.

Adam Burrows

1997-03-02T23:59:59.000Z

336

Supernova deleptonization asymmetry: Impact on self-induced flavor conversion  

E-Print Network [OSTI]

During the accretion phase of a core-collapse supernova (SN), the deleptonization flux has recently been found to develop a global dipole pattern (LESA---Lepton Emission Self-sustained Asymmetry). The $\

Sovan Chakraborty; Georg Raffelt; Hans-Thomas Janka; Bernhard Mueller

2014-12-01T23:59:59.000Z

337

Neutrino signatures of the supernova - gamma ray burst relationship  

E-Print Network [OSTI]

We calculate the TeV-PeV neutrino fluxes of gamma-ray bursts associated with supernovae, based on the observed association between GRB 030329 and supernova SN 2003dh. The neutrino spectral flux distributions can test for possible delays between the supernova and the gamma-ray burst events down to much shorter timescales than what can be resolved with photons. As an illustrative example, we calculate the probability of neutrino induced muon and electron cascade events in a km scale under-ice detector at the South Pole, from the GRB 030329. Our calculations demonstrate that km scale neutrino telescopes are expected to detect signals that will allow to constrain supernova-GRB models.

Soebur Razzaque; Peter Meszaros; Eli Waxman

2003-10-14T23:59:59.000Z

338

Gravitational wave astronomy and cosmology  

E-Print Network [OSTI]

The first direct observation of gravitational waves' action upon matter has recently been reported by the BICEP2 experiment. Advanced ground-based gravitational-wave detectors are being installed. They will soon be commissioned, and then begin searches for high-frequency gravitational waves at a sensitivity level that is widely expected to reach events involving compact objects like stellar mass black holes and neutron stars. Pulsar timing arrays continue to improve the bounds on gravitational waves at nanohertz frequencies, and may detect a signal on roughly the same timescale as ground-based detectors. The science case for space-based interferometers targeting millihertz sources is very strong. The decade of gravitational-wave discovery is poised to begin. In this writeup of a talk given at the 2013 TAUP conference, we will briefly review the physics of gravitational waves and gravitational-wave detectors, and then discuss the promise of these measurements for making cosmological measurements in the near future.

Scott A. Hughes

2014-05-02T23:59:59.000Z

339

Island Cosmology in the Landscape  

E-Print Network [OSTI]

In the eternally inflationary background driven by the metastable vacua of the landscape, it is possible that some local quantum fluctuations with the null energy condition violation can be large enough to stride over the barriers among different vacua, so that create some islands full of radiation in new vacua, and then these emergently thermalized islands will enter into the evolution of standard big bang cosmology. In this paper, we calculate the spectrum of curvature perturbation generated during the emergence of island. We find that generally the spectrum obtained is nearly scale invariant, which can be well related to that of slow roll inflation by a simple duality. This in some sense suggests a degeneracy between their scalar spectra. In addition, we also simply estimate the non-Gaussianity of perturbation, which is naturally large, yet, can lie well in the observational bound. The results shown here indicate that the island emergently thermalized in the landscape can be consistent with our observable universe.

Yun-Song Piao

2008-06-11T23:59:59.000Z

340

Introductory Lectures on Quantum Cosmology (1990)  

E-Print Network [OSTI]

We describe the modern approach to quantum cosmology, as initiated by Hartle and Hawking, Linde, Vilenkin and others. The primary aim is to explain how one determines the consequences for the late universe of a given quantum theory of cosmological initial or boundary conditions. An extensive list of references is included, together with a guide to the literature. It also includes a detailed treatment of the WKB interpretation, which is relevant to a forthcoming article by the author on the decoherent histories approach to quantum cosmology.

J. J. Halliwell

2009-09-14T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
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341

Cosmological Solutions of Emergent Noncommutative Gravity  

SciTech Connect (OSTI)

Matrix models of the Yang-Mills type lead to an emergent gravity theory, which does not require fine-tuning of a cosmological constant. We find cosmological solutions of the Friedmann-Robertson-Walker type. They generically have a big bounce, and an early inflationlike phase with graceful exit. The mechanism is purely geometrical; no ad hoc scalar fields are introduced. The solutions are stabilized through vacuum fluctuations and are thus compatible with quantum mechanics. This leads to a Milne-like universe after inflation, which appears to be in remarkably good agreement with observation and may provide an alternative to standard cosmology.

Klammer, Daniela; Steinacker, Harold [Fakultaet fuer Physik, Universitaet Wien, A-1090 Wien (Austria)

2009-06-05T23:59:59.000Z

342

Isotropic cosmological singularities: other matter models  

E-Print Network [OSTI]

Isotropic cosmological singularities are singularities which can be removed by rescaling the metric. In some cases already studied (gr-qc/9903008, gr-qc/9903009, gr-qc/9903018) existence and uniqueness of cosmological models with data at the singularity has been established. These were cosmologies with, as source, either perfect fluids with linear equations of state or massless, collisionless particles. In this article we consider how to extend these results to a variety of other matter models. These are scalar fields, massive collisionless matter, the Yang-Mills plasma of Choquet-Bruhat, or matter satisfying the Einstein-Boltzmann equation.

K. P. Tod

2002-09-20T23:59:59.000Z

343

DIVERSITY OF TYPE Ia SUPERNOVAE IMPRINTED IN CHEMICAL ABUNDANCES  

SciTech Connect (OSTI)

A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit an SN-Ia-like elemental feature including a very low [Mg/Fe] ( Almost-Equal-To - 1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr, Mn, Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth and give a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nicely explains the different [Cr, Mn, Ni/Fe] features between the two galaxies as well as the puzzling feature seen in the LMC stars exhibiting very low Ca but normal Mg abundances. Furthermore, the corresponding channel of slow SN Ia is exemplified by performing detailed nucleosynthesis calculations in the scheme of SNe Ia resulting from a 0.8 + 0.6 M{sub Sun} white dwarf merger.

Tsujimoto, Takuji [National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan); Shigeyama, Toshikazu, E-mail: taku.tsujimoto@nao.ac.jp [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2012-12-01T23:59:59.000Z

344

A Search for Fallback Disks in Four Young Supernova Remnants  

E-Print Network [OSTI]

We report on our search for the optical/infrared counterparts to the central compact objects in four young supernova remnants: Puppis A, PKS 1209-52, RCW 103, and Cassiopeia A. The X-ray point sources in these supernova remnants, likely members of a new class (or classes) of young neutron stars, are attractive targets for probing the existence of supernova ``fallback'' disks. Such disks, which are a general prediction of many supernova models, can form from supernova ejecta that fails to reach escape velocity during the initial explosion. Irradiation of the disk by a central X-ray source may lead to detectable optical/infrared emission from such a disk. We used imaging observations from ground-based telescopes in the optical and near-infrared regimes and from the Spitzer Space Telescope at 4.5 and 8.0 micron, to search for optical/infrared counterparts at the X-ray point source positions measured in these supernova remnants by the Chandra X-Ray Observatory. We did not detect any counterparts, and hence find n...

Wang, Z; Chakraborty, D; Wang, Zhongxiang; Kaplan, David L.; Chakrabarty, Deepto

2006-01-01T23:59:59.000Z

345

A Newly Recognized Very Young Supernova Remnant in M83  

E-Print Network [OSTI]

As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and GMOS, we have discovered one object whose spectrum shows very broad lines at H$\\alpha$, [O~I] 6300,6363, and [O~III] 4959,5007, similar to those from other objects classified as `late time supernovae.' Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was missed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 $\\rm M_{sun}$, and the presence of broad H$\\alpha$ in the spectrum makes a type II supernova likely....

Blair, William P; Long, Knox S; Whitmore, Bradley C; Kim, Hwihyun; Soria, Roberto; Kuntz, K D; Plucinsky, Paul P; Dopita, Michael A; Stockdale, Christopher

2015-01-01T23:59:59.000Z

346

Sloan Digital Sky Survey II (SDSS-II) Supernova Data  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

The Sloan Digital Sky Survey (SDSS) is a series of three interlocking imaging and spectroscopic surveys, carried out over an eight-year period with a dedicated 2.5m telescope located at Apache Point Observatory in Southern New Mexico. The SDSS Supernova Survey was one of those three components of SDSS and SDSS-II, a 3-year extension of the original SDSS that operated from July 2005 to July 2008. The Supernova Survey was a time-domain survey, involving repeat imaging of the same region of sky every other night, weather permitting. The primary scientific motivation was to detect and measure light curves for several hundred supernovae through repeat scans of the SDSS Southern equatorial stripe 82 (about 2.5? wide by ~120? long). Over the course of three 3-month campaigns SDSS-II SN discovered and measured multi-band lightcurves for ~500 spectroscopically confirmed Type Ia supernovae in the redshift range z=0.05-0.4. In addition, the project harvested a few hundred light curves for SNe Ia and discovered about 80 spectroscopically confirmed core-collapse supernovae (supernova types Ib/c and II).

347

Restframe I-band Hubble diagram for type Ia supernovae up to redshift z ~; 0.5  

E-Print Network [OSTI]

in STScI Symposium Ser. 13, Supernovae and gamma-ray bursts:Highlight: The Physics of Supernovae, ed. W. Hillebrandt &diagram for type Ia supernovae up to redshift z ? 0.5 ? S.

2005-01-01T23:59:59.000Z

348

Confronting the relaxation mechanism for a large cosmological constant with observations  

E-Print Network [OSTI]

In order to deal with a large cosmological constant a relaxation mechanism based on modified gravity has been proposed recently. By virtue of this mechanism the effect of the vacuum energy density of a given quantum field/string theory (no matter how big is its initial value in the early universe) can be neutralized dynamically, i.e. without fine tuning, and hence a Big Bang-like evolution of the cosmos becomes possible. Remarkably, a large class F^n_m of models of this kind, namely capable of dynamically adjusting the vacuum energy irrespective of its value and size, has been identified. In this paper, we carefully put them to the experimental test. By performing a joint likelihood analysis we confront these models with the most recent observational data on type Ia supernovae (SNIa), the Cosmic Microwave Background (CMB), the Baryonic Acoustic Oscillations (BAO) and the high redshift data on the expansion rate, so as to determine which ones are the most favored by observations. We compare the optimal relaxation models F^n_m found by this method with the standard or concordance LambdaCDM model, and find that some of these models may appear as almost indistinguishable from it. Interestingly enough, this shows that it is possible to construct viable solutions to the tough cosmological fine tuning problem with models that display the same basic phenomenological features as the concordance model.

Spyros Basilakos; Florian Bauer; Joan Sola

2012-01-03T23:59:59.000Z

349

Nuclear & Particle Physics, Astrophysics & Cosmology, Group T-2 Group Leader: Joseph A. Carlson (7-6245)  

E-Print Network [OSTI]

Arthur N. Cox 013664 anc@lanl.gov Off-site Off-site Off-site Huiayu Duan 179390 duan@unm.edu Off-site Off-site Off-site James L. Friar 080393 friar@lanl.gov 7-6184 123 129 Alexander Friedland 187483 friedland@restmass.com Off-site Off-site Off-site Nicolas Jarrett 2055914 njarret@lanl.gov 123 173 Gerard Jungman 121969

350

Inflation with stable anisotropic hair: is it cosmologically viable?  

E-Print Network [OSTI]

Recently an inflationary model with a vector field coupled to the inflaton was proposed and the phenomenology studied for the Bianchi type I spacetime. It was found that the model demonstrates a counter-example to the cosmic no-hair theorem since there exists a stable anisotropically inflationary fix-point. One of the great triumphs of inflation, however, is that it explains the observed flatness and isotropy of the universe today without requiring special initial conditions. Any acceptable model for inflation should thus explain these observations in a satisfactory way. To check whether the model meets this requirement, we introduce curvature to the background geometry and consider axisymmetric spacetimes of Bianchi type II,III and the Kantowski-Sachs metric. We show that the anisotropic Bianchi type I fix-point is an attractor for the entire family of such spacetimes. The model is predictive in the sense that the universe gets close to this fix-point after a few e-folds for a wide range of initial conditions. If inflation lasts for N e-folds, the curvature at the end of inflation is typically of order exp(-2N). The anisotropy in the expansion rate at the end of inflation, on the other hand, while being small on the one-percent level, is highly significant. We show that after the end of inflation there will be a period of isotropization lasting for about 2N/3 e-folds. After that the shear scales as the curvature and becomes dominant around N e-folds after the end of inflation. For plausible bounds on the reheat temperature the minimum number of e-folds during inflation, required for consistency with the isotropy of the supernova Ia data, lays in the interval (21,48). Thus the results obtained for our restricted class of spacetimes indicates that inflation with anisotropic hair is cosmologically viable.

Sigbjřrn Hervik; David F. Mota; Mikjel Thorsrud

2011-12-21T23:59:59.000Z

351

Simulating galactic outflows with kinetic supernova feedback  

E-Print Network [OSTI]

Feedback from star formation is thought to play a key role in the formation and evolution of galaxies, but its implementation in cosmological simulations is currently hampered by a lack of numerical resolution. We present and test a sub-grid recipe to model feedback from massive stars in cosmological smoothed particle hydrodynamics simulations. The energy is distributed in kinetic form among the gas particles surrounding recently formed stars. The impact of the feedback is studied using a suite of high-resolution simulations of isolated disc galaxies embedded in dark halos with total mass 10^{10} and 10^{12} Msol/h. We focus in particular on the effect of pressure forces on wind particles within the disc, which we turn off temporarily in some of our runs to mimic a recipe that has been widely used in the literature. We find that this popular recipe gives dramatically different results because (ram) pressure forces on expanding superbubbles determine both the structure of the disc and the development of large-scale outflows. Pressure forces exerted by expanding superbubbles puff up the disc, giving the dwarf galaxy an irregular morphology and creating a galactic fountain in the massive galaxy. Hydrodynamic drag within the disc results in a strong increase of the effective mass loading of the wind for the dwarf galaxy, but quenches much of the outflow in the case of the high-mass galaxy.

Claudio Dalla Vecchia; Joop Schaye

2008-05-07T23:59:59.000Z

352

Cosmology on the Beach - George Smoot  

SciTech Connect (OSTI)

The lecture was delivered as part of the "Cosmology at the Beach" winter school organized by Berkeley Lab's George Smoot in Los Cabos, Mexico from Jan. 12-16, 2009.

George Smoot

2009-05-06T23:59:59.000Z

353

Cosmology at the Beach Lecture: Anne Green  

ScienceCinema (OSTI)

The lecture was delivered as part of the "Cosmology at the Beach" winter school organized by Berkeley Lab's George Smoot in Los Cabos, Mexico from Jan. 12-16, 2009.  

Ann Green

2010-01-08T23:59:59.000Z

354

Cosmology at the Beach Lecture: David Hughes  

ScienceCinema (OSTI)

The lecture was delivered as part of the "Cosmology at the Beach" winter school organized by Berkeley Lab's George Smoot in Los Cabos, Mexico from Jan. 12-16, 2009.

David Hughes

2010-01-08T23:59:59.000Z

355

Cosmology at the Beach Lecture: Simon White  

ScienceCinema (OSTI)

The lecture was delivered as part of the "Cosmology at the Beach" winter school organized by Berkeley Lab's George Smoot in Los Cabos, Mexico from Jan. 12-16, 2009.

Simon White

2010-01-08T23:59:59.000Z

356

Cosmology on the Beach: Kendrick Smith  

ScienceCinema (OSTI)

The lecture was delivered as part of the "Cosmology at the Beach" winter school organized by Berkeley Lab's George Smoot in Los Cabos, Mexico from Jan. 12-16, 2009.

George Smoot

2010-01-08T23:59:59.000Z

357

Cosmology on the Beach - George Smoot  

ScienceCinema (OSTI)

The lecture was delivered as part of the "Cosmology at the Beach" winter school organized by Berkeley Lab's George Smoot in Los Cabos, Mexico from Jan. 12-16, 2009.

George Smoot

2010-01-08T23:59:59.000Z

358

Group X  

SciTech Connect (OSTI)

This project is currently under contract for research through the Department of Homeland Security until 2011. The group I was responsible for studying has to remain confidential so as not to affect the current project. All dates, reference links and authors, and other distinguishing characteristics of the original group have been removed from this report. All references to the name of this group or the individual splinter groups has been changed to 'Group X'. I have been collecting texts from a variety of sources intended for the use of recruiting and radicalizing members for Group X splinter groups for the purpose of researching the motivation and intent of leaders of those groups and their influence over the likelihood of group radicalization. This work included visiting many Group X websites to find information on splinter group leaders and finding their statements to new and old members. This proved difficult because the splinter groups of Group X are united in beliefs, but differ in public opinion. They are eager to tear each other down, prove their superiority, and yet remain anonymous. After a few weeks of intense searching, a list of eight recruiting texts and eight radicalizing texts from a variety of Group X leaders were compiled.

Fields, Susannah

2007-08-16T23:59:59.000Z

359

COMPARING THE LIGHT CURVES OF SIMULATED TYPE Ia SUPERNOVAE WITH OBSERVATIONS USING DATA-DRIVEN MODELS  

SciTech Connect (OSTI)

We propose a robust, quantitative method to compare the synthetic light curves of a Type Ia supernova (SN Ia) explosion model with a large set of observed SNe Ia, and derive a figure of merit for the explosion model's agreement with observations. The synthetic light curves are fit with the data-driven model SALT2 which returns values for stretch, color, and magnitude at peak brightness, as well as a goodness-of-fit parameter. Each fit is performed multiple times with different choices of filter bands and epoch range in order to quantify the systematic uncertainty on the fitted parameters. We use a parametric population model for the distribution of observed SN Ia parameters from large surveys, and extend it to represent red, dim, and bright outliers found in a low-redshift SN Ia data set. We discuss the potential uncertainties of this population model and find it to be reliable given the current uncertainties on cosmological parameters. Using our population model, we assign each set of fitted parameters a likelihood of being observed in nature, and a figure of merit based on this likelihood. We define a second figure of merit based on the quality of the light curve fit, and combine the two measures into an overall figure of merit for each explosion model. We compute figures of merit for a variety of one-, two-, and three-dimensional explosion models and show that our evaluation method allows meaningful inferences across a wide range of light curve quality and fitted parameters.

Diemer, Benedikt; Kessler, Richard; Graziani, Carlo; Jordan, George C. IV; Lamb, Donald Q.; Long, Min; Van Rossum, Daniel R., E-mail: bdiemer@oddjob.uchicago.edu [Flash Center for Computational Science, University of Chicago, Chicago, IL 60637 (United States)

2013-08-20T23:59:59.000Z

360

THE IMPACT OF METALLICITY ON THE RATE OF TYPE Ia SUPERNOVAE  

SciTech Connect (OSTI)

The metallicity of a star strongly affects both its evolution and the properties of the stellar remnant that results from its demise. It is generally accepted that stars with initial masses below {approx}8 M{sub Sun} leave behind white dwarfs and that some sub-population of these lead to Type Ia supernovae (SNe Ia). However, it is often tacitly assumed that metallicity has no effect on the rate of SNe Ia. We propose that a consequence of the effects of metallicity is to significantly increase the SN Ia rate in lower-metallicity galaxies, in contrast to previous expectations. This is because lower-metallicity stars leave behind higher-mass white dwarfs, which should be easier to bring to explosion. We first model SN Ia rates in relation to galaxy masses and ages alone, finding that the elevation in the rate of SNe Ia in lower-mass galaxies measured by Lick Observatory SN Search is readily explained. However, we then see that models incorporating this effect of metallicity agree just as well. Using the same parameters to estimate the cosmic SN Ia rate, we again find good agreement with data up to z Almost-Equal-To 2. We suggest that this degeneracy warrants more detailed examination of host galaxy metallicities. We discuss additional implications, including for hosts of high-z SNe Ia, the SN Ia delay time distribution, super-Chandrasekhar SNe, and cosmology.

Kistler, Matthew D. [California Institute of Technology, Mail Code 350-17, Pasadena, CA 91125 (United States); Stanek, K. Z.; Kochanek, Christopher S.; Thompson, Todd A. [Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Prieto, Jose L. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2013-06-20T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


361

Phenomenology for Supernova Ia Data Based on a New Cosmic Time  

E-Print Network [OSTI]

A new phenomenological theory for the expansion of our universe is presented. Because fundamental supporting theory is still in development, its discussion is not presented in this paper. The theory is based on a new algebraic expression for cosmic time G Rho t^2=3/32Pi, which correctly predicts the WMAP measured cosmological constants and the fundamental Hubble parameter H(t) for the expansion of the universe. A replacement for dark matter, called here "dark mass", is proposed which scales as with the expansion and incorporated. It does not react with ordinary matter, except gravitationally, and produces flat rotational curves for spiral galaxies. Also a new expression for the approaching velocity of radiation in a closed 3-sphere expanding universe is given that accounts for the early degrading negative approach of radiation for z > 1.7. The expression is v = Hr-c. Combining these three elements produces a luminosity distance dL that successfully predicts the apparent magnitude of exploding supernova Ia stars and even the new gamma ray bursts with no need for dark energy or acceleration of the expansion of the universe.

Charles B. Leffert

2007-07-26T23:59:59.000Z

362

Low-Metallicity Inhibition of Type Ia Supernovae and Galactic and Cosmic Chemical Evolution  

E-Print Network [OSTI]

We introduce a metallicity dependence of Type Ia supernova (SN Ia) rate into the Galactic and cosmic chemical evolution models. In our SN Ia progenitor scenario, the accreting white dwarf (WD) blows a strong wind to reach the Chandrasekhar mass limit. If the iron abundance of the progenitors is as low as [Fe/H] 1-2, SNe Ia can be found only in the environments where the timescale of metal enrichment is sufficiently short as in starburst galaxies and ellipticals. The low-metallicity inhibition of SNe Ia can shed new light on the following issues: 1) The limited metallicity range of the SN Ia progenitors would imply that ``evolution effects'' are relatively small for the use of high redshift SNe Ia to determine the cosmological parameters. 2) WDs of halo populations are poor producers of SNe Ia, so that the WD contribution to the halo mass is not constrained from the iron abundance in the halo. 3) The abundance patterns of globular clusters and field stars in the Galactic halo lack of SN Ia signatures in spite of their age difference of several Gyrs, which can be explained by the low-metallicity inhibition of SNe Ia. 4) It could also explain why the SN Ia contamination is not seen in the damped Ly\\alpha systems for over a wide range of redshift.

Chiaki Kobayashi; Takuji Tsujimoto; Ken'ich Nomoto; Izumi Hachisu; Mariko Kato

1998-06-25T23:59:59.000Z

363

An Inertial Reaction to Cosmological Accelerations  

E-Print Network [OSTI]

Mach's "fixed stars" are actually not fixed at all. The distant clusters of galaxies are not only receding from each observer but they are also accelerating since the rate of cosmological expansion is not constant. If the distant cosmic masses in someway constitute the frame of inertial reference then an additional force should be generated among local bodies in reaction to the apparent cosmological accelerations of the distant galaxies.

Scott Funkhouser

2005-05-17T23:59:59.000Z

364

Mass Spectrum, Actons and Cosmological Landscape  

E-Print Network [OSTI]

It is suggested that the properties of the mass spectrum of elementary particles could be related with cosmology. Solutions of the Klein-Gordon equation on the Friedmann type manifold with the finite action are constructed. These solutions (actons) have a discrete mass spectrum. We suggest that such solutions could select a universe from cosmological landscape. In particular the solutions with the finite action on de Sitter space are investigated.

V. V. Kozlov; I. V. Volovich

2006-12-13T23:59:59.000Z

365

{\\Lambda}CDM cosmology from matter only  

E-Print Network [OSTI]

I discuss a matter-only interpretation of {\\Lambda}CDM cosmology, based on conservation of energy and assuming a Machian definition of inertia. {\\Lambda}CDM cosmology can be linked to a Newtonian cosmic potential, subject to a propagating gravitational horizon. In a matter-only universe where total energy is conserved, Machian inertia related to the evolving potential may cause both deceleration and acceleration of recession.

Telkamp, Herman

2015-01-01T23:59:59.000Z

366

Cosmological Acceleration: Dark Energy or Modified Gravity?  

E-Print Network [OSTI]

We review the evidence for recently accelerating cosmological expansion or "dark energy", either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any Dark Energy constituent. If constituent Dark Energy does not exist, so that our universe is now dominated by pressure-free matter, Einstein gravity must be modified at low curvature. The vacuum symmetry of any Robertson-Walker universe then characterizes Dark Gravity as low- or high-curvature modifications of Einstein gravity. The dynamics of either kind of "dark energy" cannot be derived from the homogeneous expansion alone, but requires also observing the growth of inhomogeneities. Present and projected observations are all consistent with a small fine tuned cosmological constant, with nearly static Dark Energy, or with gravity modified at cosmological scales. The growth of cosmological fluctuations will potentially distinguish static "dark energy" from dynamic "dark energy" with equation of state $w(z)$ either changing rapidly or tracking the background matter. But to cosmologically distinguish $\\Lambda$CDM from modified gravity will require a weak lensing shear survey more ambitious than any now projected. Dvali-Gabadadze-Porrati modifications of Einstein gravity may also be detected in refined bservations in the solar system or at the intermediate Vainstein scale. Dark Energy's epicyclic character, failure to explain the original Cosmic Coincidence ("Why now?") without fine tuning, inaccessibility to laboratory or solar system tests, along with braneworld theories, now motivate future precision solar system, Vainstein-scale and cosmological-scale studies of Dark Gravity.

Sidney Bludman

2006-06-12T23:59:59.000Z

367

Quantum Coherence Arguments for Cosmological Scale  

SciTech Connect (OSTI)

Homogeneity and correlations in the observed CMB are indicative of some form of cosmological coherence in early times. Quantum coherence in the early universe would be expected to give space-like phase coherence to any effects sourced to those times. If dark energy de-coherence is assumed to occur when the rate of expansion of the relevant cosmological scale parameter in the Friedmann-Lemaitre equations is no longer supra-luminal, a critical energy density is immediately defined. It is shown that the general class of dynamical models so defined necessarily requires a spatially flat cosmology in order to be consistent with observed structure formation. The basic assumption is that the dark energy density which is fixed during de-coherence is to be identified with the cosmological constant. It is shown for the entire class of models that the expected amplitude of fluctuations driven by the dark energy de-coherence process is of the order needed to evolve into the fluctuations observed in cosmic microwave background radiation and galactic clustering. The densities involved during de-coherence which correspond to the measured dark energy density turn out to be of the electroweak symmetry restoration scale. In an inflationary cosmology, this choice of the scale parameter in the FL equations directly relates the scale of dark energy decoherence to the De Sitter scales (associated with the positive cosmological constants) at both early and late times.

Lindesay, James; /SLAC

2005-05-27T23:59:59.000Z

368

Oxygen emission in remnants of thermonuclear supernovae as a probe for their progenitor system  

E-Print Network [OSTI]

Recent progress in numerical simulations of thermonuclear supernova explosions brings up a unique opportunity in studying the progenitors of Type Ia supernovae. Coupling state-of-the-art explosion models with detailed hydrodynamical simulations of the supernova remnant evolution and the most up-to-date atomic data for X-ray emission calculations makes it possible to create realistic synthetic X-ray spectra for the supernova remnant phase. Comparing such spectra with high quality observations of supernova remnants could allow to constrain the explosion mechanism and the progenitor of the supernova. The present study focuses in particular on the oxygen emission line properties in young supernova remnants, since different explosion scenarios predict a different amount and distribution of this element. Analysis of the soft X-ray spectra from supernova remnants in the Large Magellanic Cloud and confrontation with remnant models for different explosion scenarios suggests that SNR 0509-67.5 could originate from a de...

Kosenko, D; Kromer, M; Blinnikov, S I; Pakmor, R; Kaastra, J S

2014-01-01T23:59:59.000Z

369

Sensitivity study of explosive nucleosynthesis in Type Ia supernovae: I. Modification of individual thermonuclear reaction rates  

E-Print Network [OSTI]

We explore the sensitivity of the nucleosynthesis due to type Ia supernovae with respect to uncertainties in nuclear reaction rates. We have adopted a standard one-dimensional delayed detonation model of the explosion of a Chandrasekhar-mass white dwarf, and have post-processed the thermodynamic trajectories of every mass-shell with a nucleosynthetic code, with increases (decreases) by a factor of ten on the rates of 1196 nuclear reactions. We have computed as well hydrodynamic models for different rates of the fusion reactions of 12C and of 16O. For selected reactions, we have recomputed the nucleosynthesis with alternative prescriptions for their rates taken from the JINA REACLIB database, and have analyzed the temperature ranges where modifications of their rates have the strongest effect on nucleosynthesis. The nucleosynthesis resulting from the Type Ia supernova models is quite robust with respect to variations of nuclear reaction rates, with the exception of the reaction of fusion of 12C nuclei. The energy of the explosion changes by less than \\sim4%. The changes in the nucleosynthesis due to the modification of the rates of fusion reactions are as well quite modest, for instance no species with a mass fraction larger than 0.02 experiences a variation of its yield larger than a factor of two. We provide the sensitivity of the yields of the most abundant species with respect to the rates of the most intense reactions with protons, neutrons, and alphas. In general, the yields of Fe-group nuclei are more robust than the yields of intermediate-mass elements. Among the charged particle reactions, the most influential on supernova nucleosynthesis are 30Si + p \\rightleftarrows 31P + {\\gamma}, 20Ne + {\\alpha} \\rightleftarrows 24Mg + {\\gamma}, and 24Mg + {\\alpha} \\rightleftarrows 27Al + p. The temperatures at which a modification of their rate has a larger impact are in the range 2 < T < 4 GK. (abridged)

Eduardo Bravo; Gabriel Martínez-Pinedo

2012-04-09T23:59:59.000Z

370

Quantum Vacuum Structure and Cosmology  

SciTech Connect (OSTI)

Contemporary physics faces three great riddles that lie at the intersection of quantum theory, particle physics and cosmology. They are: (1) The expansion of the universe is accelerating - an extra factor of two appears in the size; (2) Zero-point fluctuations do not gravitate - a matter of 120 orders of magnitude; and (3) The 'True' quantum vacuum state does not gravitate. The latter two are explicitly problems related to the interpretation and the physical role and relation of the quantum vacuum with and in general relativity. Their resolution may require a major advance in our formulation and understanding of a common unified approach to quantum physics and gravity. To achieve this goal we must develop an experimental basis and much of the discussion we present is devoted to this task. In the following, we examine the observations and the theory contributing to the current framework comprising these riddles. We consider an interpretation of the first riddle within the context of the universe's quantum vacuum state, and propose an experimental concept to probe the vacuum state of the universe.

Rafelski, Johann; Labun, Lance; Hadad, Yaron; /Arizona U. /Munich U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC

2011-12-05T23:59:59.000Z

371

Cosmological perturbations for imperfect fluids  

E-Print Network [OSTI]

Interacting fluids, endowed with bulk viscous stresses, are discussed in a unified perspective with the aim of generalizing the treatment of cosmological perturbation theory to the case where both fluctuating decay rates and fluctuating bulk viscosity coefficients are simultaneously present in the relativistic plasma. A gauge-invariant treatment of the qualitatively new phenomena arising in this context is provided. In a complementary approach, faithful gauge-fixed descriptions of the gravitational and hydrodynamical fluctuations are developed and exploited. To deepen the interplay between bulk viscous stresses and fluctuating decay rates, illustrative examples are proposed and discussed both analytically and numerically. Particular attention is paid to the coupled evolution of curvature and entropy fluctuations when, in the relativistic plasma, at least one of the interacting fluids possesses a fluctuating bulk viscosity coefficient. It is argued that this class of models may be usefully employed as an effective description of the decay of the inflaton as well as of other phenomena involving imperfect relativistic fluids.

Massimo Giovannini

2005-11-11T23:59:59.000Z

372

Friction forces in cosmological models  

E-Print Network [OSTI]

We investigate the dynamics of test particles undergoing friction forces in a Friedmann-Robertson-Walker (FRW) spacetime. The interaction with the background fluid is modeled by introducing a Poynting-Robertson-like friction force in the equations of motion, leading to measurable (at least in principle) deviations of the particle trajectories from geodesic motion. The effect on the peculiar velocities of the particles is investigated for various equations of state of the background fluid and different standard cosmological models. The friction force is found to have major effects on particle motion in closed FRW universes, where it turns the time-asymptotic value (approaching the recollapse) of the peculiar particle velocity from ultra-relativistic (close to light speed) to a co-moving one, i.e., zero peculiar speed. On the other hand, for open or flat universes the effect of the friction is not so significant, because the time-asymptotic peculiar particle speed is largely non-relativistic also in the geodesic case.

Donato Bini; Andrea Geralico; Daniele Gregoris; Sauro Succi

2014-08-23T23:59:59.000Z

373

Gamma-ray Burst Cosmology  

E-Print Network [OSTI]

Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to $8.8\\times10^{54}$ erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it...

Wang, F Y; Liang, E W

2015-01-01T23:59:59.000Z

374

AN ECHO OF SUPERNOVA 2008bk  

SciTech Connect (OSTI)

I have discovered a prominent light echo around the low-luminosity Type II-plateau supernova (SN) 2008bk in NGC 7793, seen in archival images obtained with the Wide Field Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST). The echo is a partial ring, brighter to the north and east than to the south and west. The analysis of the echo I present suggests that it is due to the SN light pulse scattered by a sheet, or sheets, of dust located Almost-Equal-To 15 pc from the SN. The composition of the dust is assumed to be of standard Galactic diffuse interstellar grains. The visual extinction of the dust responsible for the echo is A{sub V} Almost-Equal-To 0.05 mag in addition to the extinction due to the Galactic foreground toward the host galaxy. That the SN experienced much less overall extinction implies that it is seen through a less dense portion of the interstellar medium in its environment. The late-time HST photometry of SN 2008bk also clearly demonstrates that the progenitor star has vanished.

Van Dyk, Schuyler D., E-mail: vandyk@ipac.caltech.edu [Spitzer Science Center/Caltech, Mailcode 220-6, Pasadena, CA 91125 (United States)

2013-08-01T23:59:59.000Z

375

EVOLUTION OF PROGENITORS FOR ELECTRON CAPTURE SUPERNOVAE  

SciTech Connect (OSTI)

We provide progenitor models for electron capture supernovae (ECSNe) with detailed evolutionary calculation. We include minor electron capture nuclei using a large nuclear reaction network with updated reaction rates. For electron capture, the Coulomb correction of rates is treated and the contribution from neutron-rich isotopes is taken into account in each nuclear statistical equilibrium (NSE) composition. We calculate the evolution of the most massive super asymptotic giant branch stars and show that these stars undergo off-center carbon burning and form ONe cores at the center. These cores become heavier up to the critical mass of 1.367 M{sub Sun} and keep contracting even after the initiation of O+Ne deflagration. Inclusion of minor electron capture nuclei causes convective URCA cooling during the contraction phase, but the effect on the progenitor evolution is small. On the other hand, electron capture by neutron-rich isotopes in the NSE region has a more significant effect. We discuss the uniqueness of the critical core mass for ECSNe and the effect of wind mass loss on the plausibility of our models for ECSN progenitors.

Takahashi, Koh; Umeda, Hideyuki [Department of Astronomy, University of Tokyo, Tokyo 113-0033 (Japan); Yoshida, Takashi, E-mail: ktakahashi@astron.s.u-tokyo.ac.jp, E-mail: umeda@astron.s.u-tokyo.ac.jp, E-mail: yoshida@yukawa.kyoto-u.ac.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)

2013-07-01T23:59:59.000Z

376

EARLY EMISSION FROM TYPE Ia SUPERNOVAE  

SciTech Connect (OSTI)

A unique feature of deflagration-to-detonation (DDT) white dwarf explosion models of supernovae of type Ia is the presence of a strong shock wave propagating through the outer envelope. We consider the early emission expected in such models, which is produced by the expanding shock-heated outer part of the ejecta and precedes the emission driven by radioactive decay. We expand on earlier analyses by considering the modification of the pre-detonation density profile by the weak shocks generated during the deflagration phase, the time evolution of the opacity, and the deviation of the post-shock equation of state from that obtained for radiation pressure domination. A simple analytic model is presented and shown to provide an acceptable approximation to the results of one-dimensional numerical DDT simulations. Our analysis predicts a {approx}10{sup 3} s long UV/optical flash with a luminosity of {approx}1 to {approx}3 Multiplication-Sign 10{sup 39} erg s{sup -1}. Lower luminosity corresponds to faster (turbulent) deflagration velocity. The luminosity of the UV flash is predicted to be strongly suppressed at t > t{sub drop} {approx} 1 hr due to the deviation from pure radiation domination.

Rabinak, Itay; Waxman, Eli [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Livne, Eli, E-mail: itay.rabinak@weizmann.ac.il [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)

2012-09-20T23:59:59.000Z

377

Supernova Remnant Progenitor Masses in M31  

E-Print Network [OSTI]

Using HST photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main sequence masses (MZAMS) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and use CMD fitting to measure the recent star formation history (SFH) of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star and assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the MZAMS from this age. Because our technique is not contingent on precise location of the progenitor star, it can be applied to the location of any known SNR. We identify significant young SF around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of 2 increase over currently measured progenitor masses. We consider the remaining 6 SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped ...

Jennings, Zachary G; Murphy, Jeremiah W; Dalcanton, Julianne J; Gilbert, Karoline M; Dolphin, Andrew E; Fouesneau, Morgan; Weisz, Daniel R

2012-01-01T23:59:59.000Z

378

HOST GALAXIES OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY  

SciTech Connect (OSTI)

We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and H{alpha}-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M{sub *}/M{sub Sun }) > 8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.

Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon (France); Universite de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucleaire de Lyon (France); and others

2013-06-20T23:59:59.000Z

379

Constraints on Type IIn Supernova Progenitor Outbursts from the Lick Observatory Supernova Search  

E-Print Network [OSTI]

We searched through roughly 12 years of archival survey data acquired by the Katzman Automatic Imaging Telescope (KAIT) as part of the Lick Observatory Supernova Search (LOSS) in order to detect or place limits on possible progenitor outbursts of Type IIn supernovae (SNe~IIn). The KAIT database contains multiple pre-SN images for 5 SNe~IIn (plus one ambiguous case of a SN IIn/imposter) within 50 Mpc. No progenitor outbursts are found using the false discovery rate (FDR) statistical method in any of our targets. Instead, we derive limiting magnitudes (LMs) at the locations of the SNe. These limiting magnitudes (typically reaching $m_R \\approx 19.5\\,\\mathrm{mag}$) are compared to outbursts of SN 2009ip and $\\eta$ Car, plus additional simulated outbursts. We find that the data for SN 1999el and SN 2003dv are of sufficient quality to rule out events $\\sim40$ days before the main peak caused by initially faint SNe from blue supergiant (BSG) precursor stars, as in the cases of SN 2009ip and SN 2010mc. These SNe~IIn...

Bilinski, Christopher; Li, Weidong; Williams, G Grant; Zheng, WeiKang; Filippenko, Alexei V

2015-01-01T23:59:59.000Z

380

HOST GALAXY PROPERTIES AND HUBBLE RESIDUALS OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY  

SciTech Connect (OSTI)

We examine the relationship between Type Ia supernova (SN Ia) Hubble residuals and the properties of their host galaxies using a sample of 115 SNe Ia from the Nearby Supernova Factory. We use host galaxy stellar masses and specific star formation rates fitted from photometry for all hosts, as well as gas-phase metallicities for a subset of 69 star-forming (non-active galactic nucleus) hosts, to show that the SN Ia Hubble residuals correlate with each of these host properties. With these data we find new evidence for a correlation between SN Ia intrinsic color and host metallicity. When we combine our data with those of other published SN Ia surveys, we find the difference between mean SN Ia brightnesses in low- and high-mass hosts is 0.077 {+-} 0.014 mag. When viewed in narrow (0.2 dex) bins of host stellar mass, the data reveal apparent plateaus of Hubble residuals at high and low host masses with a rapid transition over a short mass range (9.8 {<=} log (M{sub *}/M{sub Sun }) {<=} 10.4). Although metallicity has been a favored interpretation for the origin of the Hubble residual trend with host mass, we illustrate how dust in star-forming galaxies and mean SN Ia progenitor age both evolve along the galaxy mass sequence, thereby presenting equally viable explanations for some or all of the observed SN Ia host bias.

Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon (France); Universite de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucleaire de Lyon (France); and others

2013-06-20T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Neutrino oscillation signatures of oxygen-neon-magnesium supernovae  

E-Print Network [OSTI]

We discuss the flavor conversion of neutrinos from core collapse supernovae that have oxygen-neon-magnesium (ONeMg) cores. Using the numerically calculated evolution of the star up to 650 ms post bounce, we find that, for the normal mass hierarchy, the electron neutrino flux in a detector shows signatures of two typical features of an ONeMg-core supernova: a sharp step in the density profile at the base of the He shell and a faster shock wave propagation compared to iron core supernovae. Before the shock hits the density step (t ~ 150 ms), the survival probability of electron neutrinos is about 0.68, in contrast to values of 0.32 or less for an iron core supernova. The passage of the shock through the step and its subsequent propagation cause a decrease of the survival probability and a decrease of the amplitude of oscillations in the Earth, reflecting the transition to a more adiabatic propagation inside the star. These changes affect the lower energy neutrinos first; they are faster and more sizable for larger theta_13. They are unique of ONeMg-core supernovae, and give the possibility to test the speed of the shock wave. The time modulation of the Earth effect and its negative sign at the neutronization peak are the most robust signatures in a detector.

C. Lunardini; B. Mueller; H. -Th. Janka

2007-12-18T23:59:59.000Z

382

Simulations of Turbulent Thermonuclear Burning in Type Ia Supernovae  

E-Print Network [OSTI]

Type Ia supernovae have recently received considerable attention because it appears that they can be used as "standard candles" to measure cosmic distances out to billions of light years away from us. Observations of type Ia supernovae seem to indicate that we are living in a universe that started to accelerate its expansion when it was about half its present age. These conclusions rest primarily on phenomenological models which, however, lack proper theoretical understanding, mainly because the explosion process, initiated by thermonuclear fusion of carbon and oxygen into heavier elements, is difficult to simulate even on supercomputers. Here, we investigate a new way of modeling turbulent thermonuclear deflagration fronts in white dwarfs undergoing a type Ia supernova explosion. Our approach is based on a level set method which treats the front as a mathematical discontinuity and allows for full coupling between the front geometry and the flow field. New results of the method applied to the problem of type Ia supernovae are obtained. It is shown that in 2-D with high spatial resolution and a physically motivated subgrid scale model for the nuclear flames numerically "converged" results can be obtained, but for most initial conditions the stars do not explode. In contrast, simulations in 3-D, do give the desired explosions and many of their properties, such as the explosion energies, lightcurves and nucleosynthesis products, are in very good agreement with observed type Ia supernovae.

W. Hillebrandt; M. Reinecke; W. Schmidt; F. K. Roepke; C. Travaglio; J. C. Niemeyer

2004-05-11T23:59:59.000Z

383

Spinning Fluids: A Group Theoretical Approach  

E-Print Network [OSTI]

We extend the Lagrangian formulation of relativistic non-abelian fluids in group theory language. We propose a Mathisson-Papapetrou equation for spinning fluids in terms of the reduction limit of de Sitter group. The equation we find correctly boils down to the one for non-spinning fluids. We study the application of our results for an FRW cosmological background for fluids with no vorticity and for dusts in the vicinity of a Kerr black hole. We also explore two alternative approaches based on a group theoretical formulation of particles dynamics.

Dario Capasso; Debajyoti Sarkar

2014-04-07T23:59:59.000Z

384

Understanding Supernova Neutrino Physics using Low-Energy Beta-Beams  

E-Print Network [OSTI]

We show that fitting linear combinations of low-energy beta-beam spectra to supernova-neutrino energy-distributions reconstructs the response of a nuclear target to a supernova flux in a very accurate way. This allows one to make direct predictions about the supernova-neutrino signal in a terrestrial neutrino detector.

N. Jachowicz; G. C. McLaughlin

2005-11-24T23:59:59.000Z

385

Dissipative or Conservative cosmology with dark energy ?  

E-Print Network [OSTI]

All evolutional paths for all admissible initial conditions of FRW cosmological models with dissipative dust fluid (described by dark matter, baryonic matter and dark energy) are analyzed using dynamical system approach. With that approach, one is able to see how generic the class of solutions leading to the desired property -- acceleration -- is. The theory of dynamical systems also offers a possibility of investigating all possible solutions and their stability with tools of Newtonian mechanics of a particle moving in a 1-dimensional potential which is parameterized by the cosmological scale factor. We demonstrate that flat cosmology with bulk viscosity can be treated as a conservative system with a potential function of the Chaplygin gas type. We also confront viscous models with SNIa observations. The best fitted models are obtained by minimizing the $\\chi^{2}$ function which is illustrated by residuals and $\\chi^{2}$ levels in the space of model independent parameters. The general conclusion is that SNIa data supports the viscous model without the cosmological constant. The obtained values of $\\chi^{2}$ statistic are comparable for both the viscous model and LCDM model. The Bayesian information criteria are used to compare the models with different power law parameterization of viscous effects. Our result of this analysis shows that SNIa data supports viscous cosmology more than the LCDM model if the coefficient in viscosity parameterization is fixed. The Bayes factor is also used to obtain the posterior probability of the model.

Marek Szydlowski; Orest Hrycyna

2007-11-24T23:59:59.000Z

386

Old supernova dust factory revealed at the Galactic center  

E-Print Network [OSTI]

Dust formation in supernova ejecta is currently the leading candidate to explain the large quantities of dust observed in the distant, early Universe. However, it is unclear whether the ejecta-formed dust can survive the hot interior of the supernova remnant (SNR). We present infrared observations of ~0.02 $M_\\odot$ of warm (~100 K) dust seen near the center of the ~10,000 yr-old Sgr A East SNR at the Galactic center. Our findings signify the detection of dust within an older SNR that is expanding into a relatively dense surrounding medium ($n_e$ ~ 100 $\\mathrm{cm}^{-3}$) and has survived the passage of the reverse shock. The results suggest that supernovae may indeed be the dominant dust production mechanism in the dense environment of early Universe galaxies.

Lau, Ryan M; Morris, Mark R; Li, Zhiyuan; Adams, Joseph D

2015-01-01T23:59:59.000Z

387

Neutrinos and nucleosynthesis in core-collapse supernovae  

SciTech Connect (OSTI)

Massive stars (M > 8-10 M{sub ?}) undergo core collapse at the end of their life and explode as supernova with ? 10{sup 51} erg of kinetic energy. While the detailed supernova explosion mechanism is still under investigation, reliable nucleosynthesis calculations based on successful explosions are needed to explain the observed abundances in metal-poor stars and to predict supernova yields for galactic chemical evolution studies. To predict nucleosynthesis yields for a large number of progenitor stars, computationally efficient explosion models are required. We model the core collapse, bounce and subsequent explosion of massive stars assuming spherical symmetry and using detailed microphysics and neutrino physics combined with a novel method to artificially trigger the explosion (PUSH). We discuss the role of neutrinos, the conditions in the ejecta, and the resulting nucleosynthesis.

Fröhlich, C.; Casanova, J. [Department of Physics, North Carolina State University, Raleigh, NC, 27695 (United States); Hempel, M.; Liebendörfer, M. [Departement für Physik, Universität Basel, CH-4056 Basel (Switzerland); Melton, C. A. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Perego, A. [Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt (Germany)

2014-06-24T23:59:59.000Z

388

Superluminous X-rays from a superluminous supernova  

E-Print Network [OSTI]

The discovery of a population of superluminous supernovae (SLSNe), with peak luminosities a factor of ~100 brighter than normal SNe (typically SLSNe have M_V engine, or an origin in the catastrophic destruction of the star following a loss of pressure due to pair production in an extremely massive stellar core (so-called pair instability supernovae). Here we consider constraints that can be placed on the explosion mechanism of Hydrogen-poor SLSNe (SLSNe-I) via X-ray observations, with XMM-Newton, Chandra and Swift, and show that at least one SLSNe-I is likely the brightest X-ray supernovae ever observed, with L_X ~ 10^45 ergs/s, ~150 days after its initial discovery. This is a luminosity 3 orders of magnitude higher than seen in ...

Levan, A J; Metzger, B D; Wheatley, P J; Tanvir, N R

2013-01-01T23:59:59.000Z

389

Beyond the Cosmological Standard Model  

E-Print Network [OSTI]

After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond \\Lambda, or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests. We begin by reviewing attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must screen themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives become important, and those for which second derivatives are important. Examples of the first class, such as f(R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories. We describe experimental tests, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. We discuss future tests which will be sensitive to different signatures of new physics in the gravitational sector. Parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

Austin Joyce; Bhuvnesh Jain; Justin Khoury; Mark Trodden

2014-12-15T23:59:59.000Z

390

Silicon carbide grains of type C provide evidence for the production of the unstable isotope $^{32}$Si in supernovae  

E-Print Network [OSTI]

Carbon-rich grains are observed to condense in the ejecta of recent core-collapse supernovae, within a year after the explosion. Silicon carbide grains of type X are C-rich grains with isotpic signatures of explosive supernova nucleosynthesis have been found in primitive meteorites. Much rarer silicon carbide grains of type C are a special sub-group of SiC grains from supernovae. They show peculiar abundance signatures for Si and S, isotopically heavy Si and isotopically light S, which appear to to be in disagreement with model predictions. We propose that C grains are formed mostly from C-rich stellar material exposed to lower SN shock temperatures than the more common type X grains. In this scenario, extreme $^{32}$S enrichments observed in C grains may be explained by the presence of short-lived $^{32}$Si ($\\tau$$_{1/2}$ = 153 years) in the ejecta, produced by neutron capture processes starting from the stable Si isotopes. No mixing from deeper Si-rich material and/or fractionation of Si from S due to mole...

Pignatari, M; Bertolli, M G; Trappitsch, R; Hoppe, P; Rauscher, T; Fryer, C; Herwig, F; Hirschi, R; Timmes, F X; Thielemann, F -K

2013-01-01T23:59:59.000Z

391

Constraining Cosmic Evolution of Type Ia Supernovae  

SciTech Connect (OSTI)

We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

2008-02-13T23:59:59.000Z

392

THE EXTREME HOSTS OF EXTREME SUPERNOVAE  

SciTech Connect (OSTI)

We use GALEX ultraviolet (UV) and optical integrated photometry of the hosts of 17 luminous supernovae (LSNe, having peak M{sub V} < -21) and compare them to a sample of 26, 000 galaxies from a cross-match between the SDSS DR4 spectral catalog and GALEX interim release 1.1. We place the LSN hosts on the galaxy NUV - r versus M{sub r} color-magnitude diagram (CMD) with the larger sample to illustrate how extreme they are. The LSN hosts appear to favor low-density regions of the galaxy CMD falling on the blue edge of the blue cloud toward the low-luminosity end. From the UV-optical photometry, we estimate the star formation history of the LSN hosts. The hosts have moderately low star formation rates (SFRs) and low stellar masses (M{sub *}) resulting in high specific star formation rates (sSFR). Compared with the larger sample, the LSN hosts occupy low-density regions of a diagram plotting sSFR versus M{sub *} in the area having higher sSFR and lower M{sub *}. This preference for low M{sub *}, high sSFR hosts implies that the LSNe are produced by an effect having to do with their local environment. The correlation of mass with metallicity suggests that perhaps wind-driven mass loss is the factor that prevents LSNe from arising in higher-mass, higher-metallicity hosts. The massive progenitors of the LSNe (>100 M{sub sun}), by appearing in low-SFR hosts, are potential tests for theories of the initial mass function that limit the maximum mass of a star based on the SFR.

Neill, James D.; Quimby, Robert; Ofek, Eran; Wyder, Ted K.; Martin, D. Christopher; Barlow, Tom A.; Foster, Karl; Friedman, Peter G.; Morrissey, Patrick [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Sullivan, Mark [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Gal-Yam, Avishay [Department of Particle Physics and Astrophysics, Faculty of Physics, Weizmann Institute of Science, 76100 Rehovot (Israel); Howell, D. Andrew [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States); Nugent, Peter [Lawrence Berkeley National Laboratory, MS 50F-1650, 1 Cyclotron Road, Berkeley, CA 94720-8139 (United States); Seibert, Mark [The Observatories of the Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Overzier, Roderik [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Neff, Susan G. [Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Schiminovich, David [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Bianchi, Luciana [Center for Astrophysical Sciences, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Donas, Jose [Laboratoire d'Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12 (France); Heckman, Timothy M. [Department of Physics and Astronomy, The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States)

2011-01-20T23:59:59.000Z

393

SHOCK BREAKOUT FROM TYPE Ia SUPERNOVA  

SciTech Connect (OSTI)

The mode of explosive burning in Type Ia supernovae (SNe Ia) remains an outstanding problem. It is generally thought to begin as a subsonic deflagration, but this may transition into a supersonic detonation (the delayed detonation transition, DDT). We argue that this transition leads to a breakout shock, which would provide the first unambiguous evidence that DDTs occur. Its main features are a hard X-ray flash (approx20 keV) lasting approx10{sup -2} s with a total radiated energy of approx10{sup 40} erg, followed by a cooling tail. This creates a distinct feature in the visual light curve, which is separate from the nickel decay. This cooling tail has a maximum absolute visual magnitude of M{sub V} approx -9 to -10 at approx1 day, which depends most sensitively on the white dwarf radius at the time of the DDT. As the thermal diffusion wave moves in, the composition of these surface layers may be imprinted as spectral features, which would help to discern between SN Ia progenitor models. Since this feature should accompany every SNe Ia, future deep surveys (e.g., m = 24) will see it out to a distance of approx80 Mpc, giving a maximum rate of approx60 yr{sup -1}. Archival data sets can also be used to study the early rise dictated by the shock heating (at approx20 days before maximum B-band light). A similar and slightly brighter event may also accompany core bounce during the accretion-induced collapse to a neutron star, but with a lower occurrence rate.

Piro, Anthony L.; Chang, Philip; Weinberg, Nevin N., E-mail: tpiro@astro.berkeley.ed, E-mail: pchang@astro.berkeley.ed, E-mail: nweinberg@astro.berkeley.ed [Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States)

2010-01-01T23:59:59.000Z

394

Light right-handed neutrinos: + an incursion in cosmology  

E-Print Network [OSTI]

Light right-handed neutrinos: why not? + an incursion in cosmology R. Barbieri "Neutrinos in Venice? " The typical lifetime of a new trend in high energy physics and cosmology nowadays is about 5 to 10 years

Abbondandolo, Alberto

395

Some Implications of the Cosmological Constant to Fundamental Physics  

E-Print Network [OSTI]

In the presence of a cosmological constant, ordinary Poincare' special relativity is no longer valid and must be replaced by a de Sitter special relativity, in which Minkowski space is replaced by a de Sitter spacetime. In consequence, the ordinary notions of energy and momentum change, and will satisfy a different kinematic relation. Such a theory is a different kind of a doubly special relativity. Since the only difference between the Poincare' and the de Sitter groups is the replacement of translations by certain linear combinations of translations and proper conformal transformations, the net result of this change is ultimately the breakdown of ordinary translational invariance. From the experimental point of view, therefore, a de Sitter special relativity might be probed by looking for possible violations of translational invariance. If we assume the existence of a connection between the energy scale of an experiment and the local value of the cosmological constant, there would be changes in the kinematics of massive particles which could hopefully be detected in high-energy experiments. Furthermore, due to the presence of a horizon, the usual causal structure of spacetime would be significantly modified at the Planck scale.

R. Aldrovandi; J. P. Beltran Almeida; J. G. Pereira

2007-02-12T23:59:59.000Z

396

MIXING OF CLUMPY SUPERNOVA EJECTA INTO MOLECULAR CLOUDS  

SciTech Connect (OSTI)

Several lines of evidence, from isotopic analyses of meteorites to studies of the Sun's elemental and isotopic composition, indicate that the solar system was contaminated early in its evolution by ejecta from a nearby supernova. Previous models have invoked supernova material being injected into an extant protoplanetary disk, or isotropically expanding ejecta sweeping over a distant (>10 pc) cloud core, simultaneously enriching it and triggering its collapse. Here, we consider a new astrophysical setting: the injection of clumpy supernova ejecta, as observed in the Cassiopeia A supernova remnant, into the molecular gas at the periphery of an H II region created by the supernova's progenitor star. To track these interactions, we have conducted a suite of high-resolution (1500{sup 3} effective) three-dimensional numerical hydrodynamic simulations that follow the evolution of individual clumps as they move into molecular gas. Even at these high resolutions, our simulations do not quite achieve numerical convergence, due to the challenge of properly resolving the small-scale mixing of ejecta and molecular gas, although they do allow some robust conclusions to be drawn. Isotropically exploding ejecta do not penetrate into the molecular cloud or mix with it, but, if cooling is properly accounted for, clumpy ejecta penetrate to distances {approx}10{sup 18} cm and mix effectively with large regions of star-forming molecular gas. In fact, the {approx}2 M{sub Sun} of high-metallicity ejecta from a single core-collapse supernova is likely to mix with {approx}2 Multiplication-Sign 10{sup 4} M{sub Sun} of molecular gas material as it is collapsing. Thus, all stars forming late ( Almost-Equal-To 5 Myr) in the evolution of an H II region may be contaminated by supernova ejecta at the level {approx}10{sup -4}. This level of contamination is consistent with the abundances of short-lived radionuclides and possibly some stable isotopic shifts in the early solar system and is potentially consistent with the observed variability in stellar elemental abundances. Supernova contamination of forming planetary systems may be a common, universal process.

Pan Liubin; Desch, Steven J.; Scannapieco, Evan; Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)

2012-09-01T23:59:59.000Z

397

Automata groups  

E-Print Network [OSTI]

-presentation. We also find the L-presentation for several other groups generated by three-state automata, and we describe the defining relations in the Grigorchuk groups G_w. In case when the sequence w is almost periodic these relations provide an L...

Muntyan, Yevgen

2010-01-16T23:59:59.000Z

398

Cosmological 3-point correlators from holography  

SciTech Connect (OSTI)

We investigate the non-Gaussianity of primordial cosmological perturbations using holographic methods. In particular, we derive holographic formulae that relate all cosmological 3-point correlation functions, including both scalar and tensor perturbations, to stress-energy correlation functions of a holographically dual three-dimensional quantum field theory. These results apply to general single scalar inflationary universes that at late times approach either de Sitter spacetime or accelerating power-law cosmologies. We further show that in Einstein gravity all 3-point functions involving tensors may be obtained from correlators containing only positive helicity gravitons, with the ratios of these to the correlators involving one negative helicity graviton being given by universal functions of momenta, irrespectively of the potential of the scalar field. As a by-product of this investigation, we obtain holographic formulae for the full 3-point function of the stress-energy tensor along general holographic RG flows. These results should have applications in a wider holographic context.

McFadden, Paul; Skenderis, Kostas, E-mail: P.L.McFadden@uva.nl, E-mail: K.Skenderis@uva.nl [Institute for Theoretical Physics, Science Park 904, 1090 GL Amsterdam (Netherlands)

2011-06-01T23:59:59.000Z

399

Accelerating Cosmologies with Extended Product Spaces  

E-Print Network [OSTI]

Accelerating cosmologies in extra dimensional spaces have been studied. These extra dimensional spaces are products of many spaces. The physical behaviors of accelerating cosmologies are investigated from Einstein's field equation in higher dimensional Friedmann-Robertson-Walker (FRW) universe and superstring/M theory points of view. It is found that if some assumptions of flatness are made for sector of the FRW universe, the remaining sector needs to be hyperbolic. These properties are in parallel with those found in the model of superstring/M theory. The extended product made for the superstring model did not show any more new features other than those already found. A similar accelerating phase of this product space cosmology was found with difference in numerical values of the accelerating period.

Han Siong Ch'ng

2008-10-15T23:59:59.000Z

400

Quantum Exclusion of Positive Cosmological Constant?  

E-Print Network [OSTI]

We show that a positive cosmological constant is incompatible with the quantum-corpuscular resolution of de Sitter metric in form of a coherent state. The reason is very general and is due to the quantum self-destruction of the coherent state because of the scattering of constituent graviton quanta. This process creates an irreversible quantum clock, which precludes eternal de Sitter. It also eliminates the possibility of Boltzmann brains and Poincare recurrences. This effect is expected to be part of any microscopic theory that takes into account the quantum corpuscular structure of the cosmological background. This observation puts the cosmological constant problem in a very different light, promoting it, from a naturalness problem, into a question of quantum consistency. We are learning that quantum gravity cannot tolerate exceedingly-classical sources.

Gia Dvali; Cesar Gomez

2014-12-27T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Brane f(R) gravity cosmologies  

SciTech Connect (OSTI)

By the application of the generalized Israel junction conditions we derive cosmological equations for the fourth-order f(R) brane gravity and study their cosmological solutions. We show that there exists a nonstatic solution which describes a four-dimensional de Sitter (dS{sub 4}) brane embedded in a five-dimensional anti-de Sitter (AdS{sub 5}) bulk for a vanishing Weyl tensor contribution. On the other hand, for the case of a nonvanishing Weyl tensor contribution, there exists a static brane solution only. We claim that in order to get some more general nonstatic f(R) brane configurations, one needs to admit a dynamical matter energy-momentum tensor in the bulk rather than just a bulk cosmological constant.

Balcerzak, Adam; DaPbrowski, Mariusz P. [Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin (Poland)

2010-06-15T23:59:59.000Z

402

Cosmological perturbations in mimetic matter model  

E-Print Network [OSTI]

We investigate the cosmological evolution of mimetic matter model with arbitrary scalar potential. The cosmological reconstruction is explicitly done for different choices of potential. The cases that mimetic matter model shows the evolution as Cold Dark Matter(CDM), wCDM model, dark matter and dark energy with dynamical $Om(z)$ or phantom dark energy with phantom-non-phantom crossing are presented in detail. The cosmological perturbations for such evolution are studied in mimetic matter model. For instance, the evolution behavior of the matter density contrast which is different from usual one, i.e. $\\ddot \\delta + 2 H \\dot \\delta - \\kappa ^2 \\rho \\delta /2 = 0$ is investigated. The possibility of peculiar evolution of $\\delta$ in the model under consideration is shown. Special attention is paid to the behavior of matter density contrast near to future singularity where decay of perturbations may occur much earlier the singularity.

Matsumoto, Jiro; Sushkov, Sergey V

2015-01-01T23:59:59.000Z

403

Cosmological and Astrophysical Probes of Vacuum Energy  

E-Print Network [OSTI]

Vacuum energy changes during cosmological phase transitions and becomes relatively important at epochs just before phase transitions. For a viable cosmology the vacuum energy just after a phase transition must be set by the critical temperature of the next phase transition, which exposes the cosmological constant problem from a different angle. Here we propose to experimentally test the properties of vacuum energy under circumstances different from our current vacuum. One promising avenue is to consider the effect of high density phases of QCD in neutron stars. Such phases have different vacuum expectation values and a different vacuum energy from the normal phase, which can contribute an order one fraction to the mass of neutron stars. Precise observations of the mass of neutron stars can potentially yield information about the gravitational properties of vacuum energy, which can significantly affect their mass-radius relation. A more direct test of cosmic evolution of vacuum energy could be inferred from a ...

Bellazzini, Brando; Hubisz, Jay; Serra, Javi; Terning, John

2015-01-01T23:59:59.000Z

404

Analysis of inflationary cosmological models in gauge theories of gravitation  

E-Print Network [OSTI]

Inflationary homogeneous isotropic cosmological models filled by scalar fields and ultrarelativistic matter are examined in the framework of gauge theories of gravitation. By using quadratic scalar field potential numerical analysis of flat, open and closed models is curried out. Properties of cosmological models are investigated in dependence on indefinite parameter of cosmological equations and initial conditions at a bounce. Fulfilled analysis demonstrates regular character of all cosmological models.

A. V. Minkevich; A. S. Garkun

2005-12-22T23:59:59.000Z

405

The farthest known supernova: Support for an accelerating universeand a glimpse of the epoch of deceleration  

SciTech Connect (OSTI)

We present photometric observations of an apparent Type Iasupernova (SN Ia) at a redshift of approximately 1.7, the farthest SNobserved to date. The supernova, SN 1997, was discovered in a repeatobservation by the Hubble Space Telescope (HST) of the Hubble DeepField{North (HDF-N), and serendipitously monitored with NICMOS on HSTthroughout the Thompson et al. GTO campaign. The SN type can bedetermined from the host galaxy type: an evolved, red elliptical lackingenough recent star formation to provide a significant population ofcore-collapse supernovae. The classification is further supported bydiagnostics available from the observed colors and temporal behavior ofthe SN, both of which match a typical SN Ia. The photometric record ofthe SN includes a dozen flux measurements in the I, J, and H bandsspanning 35 days in the observed frame. The redshift derived from the SNphotometry, z = 1:7 plus or minus 0:1, is in excellent agreement with theredshift estimate of z = 1:65 plus or minus 0:15 derived from the U_300B_450 V_-606 I_814 J_110 J_125 H_160 H_165 K_s photometry of the galaxy.Optical and near-infrared spectra of the host provide a very tentativespectroscopic redshift of 1.755. Fits to observations of the SN provideconstraints for the redshift-distance relation of SNe Ia and a powerfultest of the current accelerating Universe hypothesis. The apparent SNbrightness is consistent with that expected in the decelerating phase ofthe preferred cosmological model, Omega_M approximately equal to 1/3;Omega_Lambda approximately equal to 2/3. It is inconsistent with greydust or simple luminosity evolution, candidate astrophysical effectswhich could mimic previous evidence for an accelerating Universe from SNeIa at z approximately equal to 0:5. We consider several sources ofpotential systematic error including gravitational lensing, supernovamisclassification, sample selection bias, and luminosity calibrationerrors. Currently, none of these effects alone appears likely tochallenge our conclusions. Additional SNe Ia at z>1 will be requiredto test more exotic alternatives to the accelerating Universe hypothesisand to probe the nature of dark energy.

Riess, Adam G.; Nugent, Peter E.; Schmidt, Brian P.; Tonry, John; Dickinson, Mark; Gilliland, Ronald L.; Thompson, Rodger I.; Budavari,Tamas; Casertano, Stefano; Evans, Aaron S.; Filippenko, Alexei V.; Livio,Mario; Sanders, David B.; Shapley, Alice E.; Spinrad, Hyron; Steidel,Charles C.; Stern, Daniel; Surace, Jason; Veilleux, Sylvain

2001-04-01T23:59:59.000Z

406

Future Singularities and Completeness in Cosmology  

E-Print Network [OSTI]

We review recent work on the existence and nature of cosmological singularities that can be formed during the evolution of generic as well as specific cosmological spacetimes in general relativity. We first discuss necessary and sufficient conditions for the existence of geodesically incomplete spacetimes based on a tensorial analysis of the geodesic equations. We then classify the possible singularities of isotropic globally hyperbolic universes using the Bel-Robinson slice energy that closely monitors the asymptotic properties of fields near the singularity. This classification includes all known forms of spacetime singularities in isotropic universes and also predicts new types.

Spiros Cotsakis

2006-06-04T23:59:59.000Z

407

Thermodynamics of Ideal Gas in Cosmology  

E-Print Network [OSTI]

The equation of state and the state functions for the gravitational source are necessary conditions for solving cosmological model and stellar structure. The usual treatments are directly based on the laws of thermodynamics, and the physical meanings of some concepts are obscure. This letter show that, we can actually derive all explicit fundamental state functions for the ideal gas in the context of cosmology via rigorous dynamical and statistical calculation. These relations have clear physical meanings, and are valid in both non-relativistic and ultra-relativistic cases. Some features of the equation of state are important for a stable structure of a star with huge mass.

Ying-Qiu Gu

2009-10-04T23:59:59.000Z

408

Non-standard loop quantum cosmology  

E-Print Network [OSTI]

We present results concerning the nature of the cosmological big bounce(BB) transition within the loop geometry underlying loop quantum cosmology (LQC). Our canonical quantization method is an alternative to the standard LQC. An evolution parameter we use has clear interpretation both at classical and quantum levels. The physical volume operator has discrete spectrum which is bounded from below. The minimum gap in the spectrum defines a quantum of the volume. The spectra of operators are parametrized by a free parameter to be determined.

Wlodzimierz Piechocki

2010-01-19T23:59:59.000Z

409

Radiation-dominated area metric cosmology  

E-Print Network [OSTI]

We provide further crucial support for a refined, area metric structure of spacetime. Based on the solution of conceptual issues, such as the consistent coupling of fermions and the covariant identification of radiation fields on area metric backgrounds, we show that the radiation-dominated epoch of area metric cosmology is equivalent to that epoch in standard Einstein cosmology. This ensures, in particular, successful nucleosynthesis. This surprising result complements the previously derived prediction of a small late-time acceleration of an area metric universe.

Frederic P. Schuller; Mattias N. R. Wohlfarth

2007-06-12T23:59:59.000Z

410

Asymptotic safety and the cosmological constant  

E-Print Network [OSTI]

We study the non-perturbative renormalisation of quantum gravity in four dimensions. Taking care to disentangle physical degrees of freedom, we observe the topological nature of conformal fluctuations arising from the functional measure. The resulting beta functions possess an asymptotically safe fixed point with a global phase structure leading to classical general relativity for positive, negative or vanishing cosmological constant. If only the conformal fluctuations are quantised we find an asymptotically safe fixed point predicting a vanishing cosmological constant on all scales. At this fixed point we reproduce the critical exponent, $\

Kevin Falls

2014-08-01T23:59:59.000Z

411

Cosmology as Science?: From Inflation to Eternity  

ScienceCinema (OSTI)

The last decade or two have represented the golden age of observational cosmology, producing a revolution in our picture of the Universe on its largest scales, and perhaps also its smallest ones. I will argue that these recent development bring to the forefront some vexing questions about whether various fundamental assumptions about the universe are in fact falsifiable. I will focus on 3 issues: (1) "Proving" Inflation, (2) Dark Energy and Anthropic Arguments, and (3) Cosmology of the far future.Interview with Lawrence M. Krauss

None

2011-10-06T23:59:59.000Z

412

Shockwaves in Supernovae: New Implications on the Diffuse Supernova Neutrino Background  

E-Print Network [OSTI]

We investigate shock wave effects upon the diffuse supernova neutrino background using dynamic profiles taken from hydrodynamical simulations and calculating the neutrino evolution in three flavors with the S-matrix formalism. We show that the shock wave impact is significant and introduces modifications of the relic fluxes by about $20 \\%$ and of the associated event rates at the level of $10-20 \\%$. Such an effect is important since it is of the same order as the rate variation introduced when different oscillation scenarios (i.e. hierarchy or $\\theta_{13}$) are considered. In addition, due to the shock wave, the rates become less sensitive to collective effects, in the inverted hierarchy and when $\\sin^2 2 \\theta_{13}$ is between the Chooz limit and $10^{-5}$. We propose a simplified model to account for shock wave effects in future predictions.

Sebastien Galais; James Kneller; Cristina Volpe; Jerome Gava

2009-11-18T23:59:59.000Z

413

Absolute Magnitude Distribution And Light Curves Of Gamma-Ray Burst Supernovae  

E-Print Network [OSTI]

Photometry data were collected from the literature and analyzed for supernovae that are thought to have a gamma-ray burst association. There are several gamma-ray burst afterglow light curves that appear to have a supernova component. For these light curves, the supernova component was extracted and analyzed. A supernova light curve model was used to help determine the peak absolute magnitudes as well as estimates for the kinetic energy, ejected mass and nickel mass in the explosion. The peak absolute magnitudes are, on average, brighter than those of similar supernovae (stripped-envelope supernovae) that do not have a gamma-ray burst association, but this can easily be due to a selection effect. However, the kinetic energies and ejected masses were found to be considerably higher, on average, than those of similar supernovae without a gamma-ray burst association.

Dean Richardson

2008-12-10T23:59:59.000Z

414

Impacts of different SNLS3 light-curve fitters on cosmological consequences of interacting dark energy models  

E-Print Network [OSTI]

Aims: We explore the cosmological consequences of interacting dark energy (IDE) models using the Supernova Legacy Survey three-year (SNLS3) data sets. In particular, we focus on the impacts of different SNLS3 light-curve fitters (LCF) (corresponding to the "SALT2", the "SiFTO", and the "Combined" supernova sample). Methods: Firstly, making use of the three SNLS3 data sets, as well as the observational data from the cosmic microwave background (CMB), the galaxy clustering (GC) and the direct measurement of Hubble constant $H_0$, we constrain the parameter spaces of three IDE models. Then, we plot the cosmic evolutions of Hubble diagram $H(z)$, deceleration diagram $q(z)$ and statefinder hierarchy $\\{S^{(1)}_3, S^{(1)}_4\\}$, and check whether or not these dark energy (DE) diagnosis can distinguish the differences among the results of different LCF. At last, we perform high-redshift cosmic age test using three old high redshift objects (OHRO), and explore the fate of the Universe. Results: For all the IDE models...

Hu, Yazhou; Li, Nan; Wang, Shuang

2015-01-01T23:59:59.000Z

415

SUPERNOVA REMNANT PROGENITOR MASSES IN M31  

SciTech Connect (OSTI)

Using Hubble Space Telescope photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main-sequence masses (M{sub ZAMS}) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and employ CMD fitting to measure the recent star formation history of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star, then assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the M{sub ZAMS} from this age. Because our technique is not contingent on identification or precise location of the progenitor star, it can be applied to the location of any known SNRs. We identify significant young star formation around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of {approx}2 increase over currently measured progenitor masses. We consider the remaining six SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped their birth sites. In general, the distribution of recovered progenitor masses is bottom-heavy, showing a paucity of the most massive stars. If we assume a single power-law distribution, dN/dM{proportional_to}M{sup {alpha}}, then we find a distribution that is steeper than a Salpeter initial mass function (IMF) ({alpha} = -2.35). In particular, we find values of {alpha} outside the range -2.7 {>=} {alpha} {>=} -4.4 to be inconsistent with our measured distribution at 95% confidence. If instead we assume a distribution that follows a Salpeter IMF up to some maximum mass, then we find that values of M{sub Max} > 26 are inconsistent with the measured distribution at 95% confidence. In either scenario, the data suggest that some fraction of massive stars may not explode. The result is preliminary and requires more SNRs and further analysis. In addition, we use our distribution to estimate a minimum mass for core collapse between 7.0 and 7.8 M{sub Sun }.

Jennings, Zachary G.; Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Fouesneau, Morgan; Weisz, Daniel R. [Department of Astronomy, University of Washington Seattle, Box 351580, WA 98195 (United States); Murphy, Jeremiah W. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Dolphin, Andrew E., E-mail: zachjenn@uw.edu, E-mail: adolphin@raytheon.com [Raytheon, 1151 East Hermans Road, Tucson, AZ 85706 (United States)

2012-12-10T23:59:59.000Z

416

Generalized quantum gravity condensates for homogeneous geometries and cosmology  

E-Print Network [OSTI]

We construct a generalized class of quantum gravity condensate states, that allows the description of continuum homogeneous quantum geometries within the full theory. They are based on similar ideas already applied to extract effective cosmological dynamics from the group field theory formalism, and thus also from loop quantum gravity. However, they represent an improvement over the simplest condensates used in the literature, in that they are defined by an infinite superposition of graph-based states encoding in a precise way the topology of the spatial manifold. The construction is based on the definition of refinement operators on spin network states, written in a second quantized language. The construction lends itself easily to be applied also to the case of spherically symmetric quantum geometries.

Daniele Oriti; Daniele Pranzetti; James P. Ryan; Lorenzo Sindoni

2015-01-05T23:59:59.000Z

417

How to See the Supernova Berkeley Lab Just Discovered  

Broader source: Energy.gov [DOE]

According to astronomers, this is the closest and brightest supernova of this type detected in the last 30 years and will be closely studied for years to come. In this video, Berkeley Lab's Peter Nugent explains how to find the event with a small telescope or pair of binoculars.

418

Thermonuclear Supernovae: Simulations of the Deflagration Stage and Their Implications  

E-Print Network [OSTI]

Large-scale three-dimensional numerical simulations of the deflagration stage of a thermonuclear supernova explosion show the formation and evolution of a highly convoluted turbulent flame in a gravitational field of an expanding carbon-oxygen white dwarf. The flame dynamics is dominated by the gravity-induced Rayleigh-Taylor instability that controls the burning rate. The thermonuclear deflagration releases enough energy to produce a healthy explosion. The turbulent flame, however, leaves large amounts of unburnt and partially burnt material near the star center, whereas observations imply these materials only in outer layers. This disagreement could be resolved if the deflagration triggers a detonation. 1 According to observations and models, many stars that steadily burn their nuclear fuel for millions or billions of years suddenly end their lives with a powerful explosion that produces a bright object called a supernova. A supernova explosion can be powered either by the gravitational energy released during the core collapse of a massive star, or by the nuclear energy released by explosive thermonuclear burning of a star. Here, we focus on thermonuclear supernovae that belong to the Type Ia (SN Ia) in the observation-based classification (1-3).

V. N. Gamezo; A. M. Khokhlov; E. S. Oran; A. Y. Chtchelkanova; R. O. Rosenberg

2003-01-01T23:59:59.000Z

419

Thermonuclear Supernovae: Simulations of the Deflagration Stage and Their Implications  

E-Print Network [OSTI]

Large-scale three-dimensional numerical simulations of the deflagration stage of a thermonuclear supernova explosion show the formation and evolution of a highly convoluted turbulent flame in a gravitational field of an expanding carbon-oxygen white dwarf. The flame dynamics is dominated by the

V. N. Gamezo; A. M. Khokhlov; E. S. Oran; A. Y. Chtchelkanova; R. O. Rosenberg

2003-01-01T23:59:59.000Z

420

INJECTION OF SUPERNOVA DUST IN NEARBY PROTOPLANETARY DISKS  

SciTech Connect (OSTI)

The early solar system contained a number of short-lived radionuclides (SLRs) such as {sup 26}Al with half-lives <15 Myr. The one-time presence of {sup 60}Fe strongly suggests that the source of these radionuclides was a nearby supernova. In this paper, we investigate the 'aerogel' model, which hypothesizes that the solar system's SLRs were injected directly into the solar system's protoplanetary disk from a supernova within the same star-forming region. Previous work has shown that disks generally survive the impact of supernova ejecta, but also that little gaseous ejecta can be injected into the disk. The aerogel model hypothesizes that radionuclides in the ejecta condensed into micron-sized dust grains that were injected directly into the solar nebula disk. Here, we discuss the density structure of supernova ejecta and the observational support for dust condensation in the ejecta. We argue that supernova ejecta are clumpy and describe a model to quantify this clumpiness. We also argue that infrared observations may be underestimating the fraction of material that condenses into dust. Building on calculations of how supernova ejecta interact with protoplanetary disks, we calculate the efficiency with which dust grains in the ejecta are injected into a disk. We find that about 70% of material in grains roughly 0.4 {mu}m in diameter can be injected into disks. If ejecta are clumpy, the solar nebula was struck by a clump with higher-than-average {sup 26}Al and {sup 60}Fe, and these elements condensed efficiently into large grains, then the abundances of SLRs in the early solar system can be explained, even if the disk lies 2 pc from the supernova explosion. The probability that all these factors are met is low, perhaps {approx}10{sup -3}-10{sup -2}, and receiving as much {sup 26}Al and {sup 60}Fe as the solar system did may be a rare event. Still, the aerogel model remains a viable explanation for the origins of the radionuclides in the early solar system, and may be the most plausible one.

Ouellette, N. [Department of Physics, Arizona State University, P.O. Box 871504, Tempe, AZ 85287-1504 (United States); Desch, S. J.; Hester, J. J. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)

2010-03-10T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


421

A review of "1604-2004: Supernovae as Cosmological Lighthouses." by Massimo Turatto, Stefano Benetti, Luca Zampieri, William Shea, eds.  

E-Print Network [OSTI]

phenomena, such as SN 1572 and the comet in 1577, which were carefully studied by Tycho Brahe (1546-1601). The research carried out by the Danish astrono- mer is the subject of the paper by Owen Gingerich, ?Tycho Brahe and the Nova of 1572? (3...-12). Gingerich, who belongs to the Harvard Smithsonian Center for Astrophysics, reports the words expressed by Brahe in order to point out the importance of that celestial novelty: ?I was led into such per- plexity by the unbelievability of the thing that I began...

Giostra, Alessandro

2006-01-01T23:59:59.000Z

422

Surface Tension and the Cosmological Constant  

E-Print Network [OSTI]

The astronomically observed value of the cosmological constant is small but non-zero. This raises two questions together known as the cosmological constant problem a) why is lambda so nearly zero? b) why is lambda not EXACTLY zero? Sorkin has proposed that b) can be naturally explained as a one by square root N fluctuation by invoking discreteness of spacetime at the Planck scale due to quantum gravity. In this paper we shed light on these questions by developing an analogy between the cosmological constant and the surface tension of membranes. The ``cosmological constant problem'' has a natural analogue in the membrane context: the vanishingly small surface tension of fluid membranes provides an example where question a) above arises and is answered. We go on to find a direct analogue of Sorkin's proposal for answering question b) in the membrane context, where the discreteness of spacetime translates into the molecular structure of matter. We propose analogue experiments to probe a small and fluctuating surface tension in fluid membranes. A counterpart of dimensional reduction a la Kaluza-Klein and large extra dimensions also appears in the physics of fluid membranes.

Joseph Samuel; Supurna Sinha

2006-04-18T23:59:59.000Z

423

ccsd00000531 Early Cosmology and Fundamental Physics  

E-Print Network [OSTI]

, open problems and future perspectives in connection with dark energy and string theory are overviewed. Contents I. The history of the universe 1 II. Fundamental Physics 2 III. Essentials of Cosmology 3 IV and Outlook 13 References 14 I. THE HISTORY OF THE UNIVERSE The history of the universe is a history

424

Warm inflationary model in loop quantum cosmology  

SciTech Connect (OSTI)

A warm inflationary universe model in loop quantum cosmology is studied. In general we discuss the condition of inflation in this framework. By using a chaotic potential, V({phi}){proportional_to}{phi}{sup 2}, we develop a model where the dissipation coefficient {Gamma}={Gamma}{sub 0}=constant. We use recent astronomical observations for constraining the parameters appearing in our model.

Herrera, Ramon [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Avenida Brasil 2950, Casilla 4059, Valparaiso (Chile)

2010-06-15T23:59:59.000Z

425

Observed Cosmological Redshifts Support Contracting Accelerating Universe  

E-Print Network [OSTI]

The main argument that Universe is currently expanding is observed redshift increase by distance. However, this conclusion may not be correct, because cosmological redshift depends only on the scaling factors, the change in the size of the universe during the time of light propagation and is not related to the speed of observer or speed of the object emitting the light. An observer in expanding universe will measure the same redshift as observer in contracting universe with the same scaling. This was not taken into account in analysing the SN Ia data related to the universe acceleration. Possibility that universe may contract, but that the observed light is cosmologically redshifted allows for completely different set of cosmological parameters $\\Omega_M, \\Omega_{\\Lambda}$, including the solution $\\Omega_M=1, \\Omega_{\\Lambda}=0$. The contracting and in the same time accelerating universe explains observed deceleration and acceleration in SN Ia data, but also gives significantly larger value for the age of the universe, $t_0 = 24$ Gyr. This allows to reconsider classical cosmological models with $\\Lambda =0$. The contracting stage also may explain the observed association of high redshifted quasars to low redshifted galaxies.

Branislav Vlahovic

2012-07-02T23:59:59.000Z

426

Cosmology at the Beach Lecture: Wayne Hu  

ScienceCinema (OSTI)

Wayne Hu lectures on Secondary Anisotropy in the CMB. The lecture is the first in a series of 3 he delivered as part of the "Cosmology at the Beach" winter school organized by Berkeley Lab's George Smoot in Los Cabos, Mexico from Jan. 12-16, 2009.

Wayne Hu

2010-01-08T23:59:59.000Z

427

Cosmology with SKA Radio Continuum Surveys  

E-Print Network [OSTI]

Radio continuum surveys have, in the past, been of restricted use in cosmology. Most studies have concentrated on cross-correlations with the cosmic microwave background to detect the integrated Sachs-Wolfe effect, due to the large sky areas that can be surveyed. As we move into the SKA era, radio continuum surveys will have sufficient source density and sky area to play a major role in cosmology on the largest scales. In this chapter we summarise the experiments that can be carried out with the SKA as it is built up through the coming decade. We show that the SKA can play a unique role in constraining the non-Gaussianity parameter to \\sigma(f_NL) ~ 1, and provide a unique handle on the systematics that inhibit weak lensing surveys. The SKA will also provide the necessary data to test the isotropy of the Universe at redshifts of order unity and thus evaluate the robustness of the cosmological principle.Thus, SKA continuum surveys will turn radio observations into a central probe of cosmological research in th...

Jarvis, Matt J; Blake, Chris; Brown, Michael L; Lindsay, Sam N; Raccanelli, Alvise; Santos, Mario; Schwarz, Dominik

2015-01-01T23:59:59.000Z

428

COSMOLOGICAL LITHIUM PROBLEM: A DIFFERENT APPROACH  

E-Print Network [OSTI]

LITHIUM 7Li sources BBN cosmic-ray interactions (ingredients: shock waves, magnetic field, chargedCOSMOLOGICAL LITHIUM PROBLEM: A DIFFERENT APPROACH Tijana Prodanovi, University of Novi Sad Tamara Observations - boxes 4He ­ OK D ­ right on! 7Li ­ problem! Factor of 3-4 discrepancy! LITHIUM PROBLEM

?umer, Slobodan

429

Cosmologies with a time dependent vacuum  

E-Print Network [OSTI]

The idea that the cosmological term, Lambda, should be a time dependent quantity in cosmology is a most natural one. It is difficult to conceive an expanding universe with a strictly constant vacuum energy density, namely one that has remained immutable since the origin of time. A smoothly evolving vacuum energy density that inherits its time-dependence from cosmological functions, such as the Hubble rate or the scale factor, is not only a qualitatively more plausible and intuitive idea, but is also suggested by fundamental physics, in particular by quantum field theory (QFT) in curved space-time. To implement this notion, is not strictly necessary to resort to ad hoc scalar fields, as usually done in the literature (e.g. in quintessence formulations and the like). A "running" Lambda term can be expected on very similar grounds as one expects (and observes) the running of couplings and masses with a physical energy scale in QFT. Furthermore, the experimental evidence that the equation of state of the dark energy could be evolving with time/redshift (including the possibility that it might currently behave phantom-like) suggests that a time-variable Lambda term (possibly accompanied by a variable Newton's gravitational coupling G=G(t)) could account in a natural way for all these features. Remarkably enough, a class of these models (the "new cosmon") could even be the clue for solving the old cosmological constant problem, including the coincidence problem.

Joan Sola

2011-02-09T23:59:59.000Z

430

Fluctuation, Dissipation and Irreversibility in Cosmology  

E-Print Network [OSTI]

We discuss the appearance of time-asymmetric behavior in physical processes in cosmology and in the dynamics of the Universe itself. We begin with an analysis of the nature and origin of irreversibility in well-known physical processes such as dispersion, diffusion, dissipation and mixing, and make the distinction between processes whose irreversibility arises from the stipulation of special initial conditions, and those arising from the system's interaction with a coarse-grained environment. We then study the irreversibility associated with quantum fluctuations in cosmological processes like particle creation and the `birth of the Universe'. We suggest that the backreaction effect of such quantum processes can be understood as the manifestation of a fluctuation-dissipation relation relating fluctuations of quantum fields to dissipations in the dynamics of spacetime. For the same reason it is shown that dissipation is bound to appear in the dynamics of minisuperspace cosmologies. This provides a natural course for the emergence of a cosmological and thermodynamic arrow of time and suggests a meaningful definition of gravitational entropy. We conclude with a discussion on the criteria for the choice of coarse-grainings and the stability of persistent physical structures. Invited Talk given at the Conference on The Physical Origin of Time-Asymmetry Huelva, Spain, Oct. 1991, Proceedings eds. J. J. Halliwell, J. Perez-Mercader and W. H. Zurek, Cambridge University Press, 1993

B. L. Hu

1993-02-18T23:59:59.000Z

431

Cosmological model with movement in fifth dimension  

E-Print Network [OSTI]

Presented cosmological model is 3D brane world sheet moved in extra dimension with variable scale factor. Analysis of the geodesic motion of the test particle gives settle explanation of the Pioneer effect. It is found that for considered metric the solution of the semi-classical Einstein equations with various parameters conforms to isotropic expanded and anisotropic stationary universe.

W. B. Belayev

2001-10-24T23:59:59.000Z

432

A Critical Review of Classical Bouncing Cosmologies  

E-Print Network [OSTI]

Given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. The Planck data shows an unmistakably red, quasi scale-invariant, purely adiabatic primordial power spectrum and no primary non-Gaussianities. While these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. Such models face many problems, both of the purely theoretical kind, such as the necessity of violating the NEC and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. We provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. For example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-Gaussianities often result. We highlight several promising attempts to violate the NEC without introducing dangerous instabilities at the classical and/or quantum level. If primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. We conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. The constraints and lessons learned as laid out in this review might guide future research.

Diana Battefeld; Patrick Peter

2014-12-02T23:59:59.000Z

433

The Cosmological Constant and the String Landscape  

E-Print Network [OSTI]

Theories of the cosmological constant fall into two classes, those in which the vacuum energy is fixed by the fundamental theory and those in which it is adjustable in some way. For each class we discuss key challenges. The string theory landscape is an example of an adjustment mechanism. We discuss the status of this idea, and future directions.

Joseph Polchinski

2006-04-21T23:59:59.000Z

434

The First Second of a Type-II Supernova: Convection, Accretion, and Shock Propagation  

E-Print Network [OSTI]

One- and two-dimensional hydrodynamical simulations of neutrino-driven supernova explosions are discussed. The simulations cover the phase between the stagnation of the prompt shock and about one second after core bounce. Systematic variation of the neutrino fluxes from the neutrino sphere shows that the explosion energy, explosion time scale, initial mass of the protoneutron star, and explosive nucleosynthesis of iron-group elements depend sensitively on the strength of the neutrino heating during the first few 100 ms after shock formation. Convective overturn in the neutrino-heated region behind the shock is a crucial help for the explosion only in a narrow window of neutrino luminosities. Here powerful explosions can be obtained only in the multi-dimensional case. For higher core-neutrino fluxes also spherically symmetrical models yield energetic explosions, while for lower luminosities even with convection no strong explosions occur.

H. -Thomas Janka; Ewald Mueller

1995-03-03T23:59:59.000Z

435

Excited-state OH Masers and Supernova Remnants  

E-Print Network [OSTI]

The collisionally pumped, ground-state 1720 MHz maser line of OH is widely recognized as a tracer for shocked regions and observed in star forming regions and supernova remnants. Whereas some lines of excited states of OH have been detected and studied in star forming regions, the subject of excited-state OH in supernova remnants -- where high collision rates are to be expected -- is only recently being addressed. Modeling of collisional excitation of OH demonstrates that 1720, 4765 and 6049 MHz masers can occur under similar conditions in regions of shocked gas. In particular, the 6049 and 4765 MHz masers become more significant at increased OH column densities where the 1720 MHz masers begin to be quenched. In supernova remnants, the detection of excited-state OH line maser emission could therefore serve as a probe of regions of higher column densities. Using the Very Large Array, we searched for excited-state OH in the 4.7, 7.8, 8.2 and 23.8 GHz lines in four well studied supernova remnants with strong 1720 MHz maser emission (SgrAEast, W28, W44 and IC443). No detections were made, at typical detection limits of around 10 mJy/beam. The search for the 6 GHz lines were done using Effelsberg since the VLA receivers did not cover those frequencies, and are reported on in an accompanying letter (Fish, Sjouwerman & Pihlstrom 2007). We also cross-correlated the positions of known supernova remnants with the positions of 1612 MHz maser emission obtained from blind surveys. No probable associations were found, perhaps except in the SgrAEast region. The lack of detections of excited-state OH indicates that the OH column densities suffice for 1720 MHz inversion but not for inversion of excited-state transitions, consistent with the expected results for C-type shocks.

Ylva M. Pihlström; Vincent L. Fish; Loránt O. Sjouwerman; Laura K. Zschaechner; Philip B. Lockett; Moshe Elitzur

2007-12-29T23:59:59.000Z

436

Cosmology with a stiff matter era  

E-Print Network [OSTI]

We provide a simple analytical solution of the Friedmann equations for a universe made of stiff matter, dust matter, and dark energy. A stiff matter era is present in the cosmological model of Zel'dovich (1972) where the primordial universe is assumed to be made of a cold gas of baryons. It also occurs in certain cosmological models where dark matter is made of relativistic self-gravitating Bose-Einstein condensates (BECs). When the energy density of the stiff matter is positive, the primordial universe is singular. It starts from a state with a vanishing scale factor and an infinite density. We consider the possibility that the energy density of the stiff matter is negative (anti-stiff matter). This happens, for example, when the BECs have an attractive self-interaction. In that case, the primordial universe is non-singular. It starts from a state in which the scale factor is finite and the energy density is equal to zero. For the sake of generality, we consider a cosmological constant of arbitrary sign. When the cosmological constant is positive, the universe asymptotically reaches a de Sitter phase where the scale factor increases exponentially rapidly. This can account for the accelerating expansion of the universe that we observe at present. When the cosmological constant is negative (anti-de Sitter), the evolution of the universe is cyclic. Therefore, depending on the sign of the energy density of the stiff matter and of the dark energy, we obtain singular and non-singular expanding or cyclic universes.

Pierre-Henri Chavanis

2014-11-27T23:59:59.000Z

437

THE SUPERNOVA THAT DESTROYED A PROTOGALAXY: PROMPT CHEMICAL ENRICHMENT AND SUPERMASSIVE BLACK HOLE GROWTH  

SciTech Connect (OSTI)

The first primitive galaxies formed from accretion and mergers by z {approx} 15, and were primarily responsible for cosmological reionization and the chemical enrichment of the early cosmos. But a few of these galaxies may have formed in the presence of strong Lyman-Werner UV fluxes that sterilized them of H{sub 2}, preventing them from forming stars or expelling heavy elements into the intergalactic medium prior to assembly. At masses of 10{sup 8} M{sub Sun} and virial temperatures of 10{sup 4} K, these halos began to rapidly cool by atomic lines, perhaps forming 10{sup 4}-10{sup 6} M{sub Sun} Pop III stars and, later, the seeds of supermassive black holes. We have modeled the explosion of a supermassive Pop III star in the dense core of a line-cooled protogalaxy with the ZEUS-MP code. We find that the supernova (SN) expands to a radius of {approx}1 kpc, briefly engulfing the entire galaxy, but then collapses back into the potential well of the dark matter. Fallback fully mixes the interior of the protogalaxy with metals, igniting a violent starburst and fueling the rapid growth of a massive black hole at its center. The starburst would populate the protogalaxy with stars in greater numbers and at higher metallicities than in more slowly evolving, nearby halos. The SN remnant becomes a strong synchrotron source that can be observed with eVLA and eMERLIN and has a unique signature that easily distinguishes it from less energetic SN remnants. Such explosions, and their attendant starbursts, may well have marked the birthplaces of supermassive black holes on the sky.

Whalen, Daniel J.; Johnson, Jarrett L.; Smidt, Joseph [T-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Meiksin, Avery [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Heger, Alexander [Monash Centre for Astrophysics, Monash University, Victoria 3800 (Australia); Even, Wesley; Fryer, Chris L. [CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2013-09-01T23:59:59.000Z

438

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

E-Print Network [OSTI]

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 ($\\Omega _{b}h^{2}=0.022161$, 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 1$\\sigma $ 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 $\\Omega _{CDM}=0.22$. The fit is as good as for the $\\Lambda $CDM 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.

Zoltán Keresztes; László Á. Gergely

2014-12-25T23:59:59.000Z

439

2004 NaturePublishing Group as well (see Supplementary Table 2 and Supplementary Methods).  

E-Print Network [OSTI]

stars of Type Ia supernovae. Astrophys. J. 550, L53­L56 (2001). 9. Ruiz-Lapuente, P. Tycho Brahe©2004 NaturePublishing Group as well (see Supplementary Table 2 and Supplementary Methods). Tycho G 3 larger than the mean velocity value at 3 kpc. If Tycho G is the companion star as suggested by its

Forget, François

440

Finite Future Cosmological Singularity Times and Maximum Predictability Times in a Nonlinear FRW-KG Scalar Cosmology  

E-Print Network [OSTI]

We investigate the relative time scales associated with finite future cosmological singularities, especially those classified as Big Rip cosmologies, and the maximum predictability time of a coupled FRW-KG scalar cosmology with chaotic regimes. Our approach is to show that by starting with a FRW-KG scalar cosmology with a potential that admits an analytical solution resulting in a finite time future singularity there exists a Lyapunov time scale that is earlier than the formation of the singularity. For this singularity both the cosmological scale parameter a(t) and the Hubble parameter H(t) become infinite at a finite future time, the Big Rip time. We compare this time scale to the predictability time scale for a chaotic FRW-KG scalar cosmology. We find that there are cases where the chaotic time scale is earlier than the Big Rip singularity calling for special care in interpreting and predicting the formation of the future cosmological singularity.

John Max Wilson; Keith Andrew

2012-07-27T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Supernova rates from the Southern inTermediate Redshift ESO Supernova Search (STRESS)  

E-Print Network [OSTI]

To measure the supernova (SN) rates at intermediate redshift we performed the Southern inTermediate Redshift ESO Supernova Search (STRESS). Unlike most of the current high redshift SN searches, this survey was specifically designed to estimate the rate for both type Ia and core collapse (CC) SNe. We counted the SNe discovered in a selected galaxy sample measuring SN rate per unit blue band luminosity. Our analysis is based on a sample of ~43000 galaxies and on 25 spectroscopically confirmed SNe plus 64 selected SN candidates. Our approach is aimed at obtaining a direct comparison of the high redshift and local rates and at investigating the dependence of the rates on specific galaxy properties, most notably their colour. The type Ia SN rate, at mean redshift z=0.3, amounts to 0.22^{+0.10+0.16}_{-0.08 -0.14} h_{70}^2 SNu, while the CC SN rate, at z=0.21, is 0.82^{+0.31 +0.30}_{-0.24 -0.26} h_{70}^2 SNu. The quoted errors are the statistical and systematic uncertainties. With respect to local value, the CC SN rate at z=0.2 is higher by a factor of ~2 already at redshift, whereas the type Ia SN rate remains almost constant. This implies that a significant fraction of SN Ia progenitors has a lifetime longer than 2-3 Gyr. We also measured the SN rates in the red and blue galaxies and found that the SN Ia rate seems to be constant in galaxies of different colour, whereas the CC SN rate seems to peak in blue galaxies, as in the local Universe. SN rates per unit volume were found to be consistent with other measurements showing a steeper evolution with redshift for CC SNe with respect to SNe Ia. Finally we have exploited the link between star formation (SF) and SN rates to predict the evolutionary behaviour of the SN rates and compare it with the path indicated by observations.

M. T. Botticella; M. Riello; E. Cappellaro; S. Benetti; G. Altavilla; A. Pastorello; M. Turatto; L. Greggio; F. Patat; S. Valenti; L. Zampieri; A. Harutyunyan; G. Pignata; S. Taubenberger

2007-10-19T23:59:59.000Z

442

Hamiltonian reduction of Bianchi Cosmologies  

E-Print Network [OSTI]

It was noted recently that the ADM-diffeomorphism-constraint does not generate all observed symmetries for several Bianchi-models. We will suggest not to use the ADM-constraint restricted to homogeneous variables, but some equivalent which is derived from a restricted action principle. This will generate all homogeneity preserving diffeomorphisms, which will be shown to be automorphism generating vector fields, in class A and class B models. Following Dirac's constraint formalism one will naturally be restricted to the unimodular part of the automorphism group.

J. Schirmer

1994-08-04T23:59:59.000Z

443

SUPERNOVAE AND AGN DRIVEN GALACTIC OUTFLOWS  

SciTech Connect (OSTI)

We present analytical solutions for winds from galaxies with a Navarro-Frank-White (NFW) dark matter halo. We consider winds driven by energy and mass injection from multiple supernovae (SNe), as well as momentum injection due to radiation from a central black hole. We find that the wind dynamics depends on three velocity scales: (1) v{sub *}{approx}( E-dot / 2 M-dot ){sup 1/2} describes the effect of starburst activity, with E-dot and M-dot as energy and mass injection rate in a central region of radius R; (2) v {sub .} {approx} (GM {sub .}/2R){sup 1/2} for the effect of a central black hole of mass M {sub .} on gas at distance R; and (3) v{sub s}=(GM{sub h} / 2Cr{sub s}){sup 1/2}, which is closely related to the circular speed (v{sub c} ) for an NFW halo, where r{sub s} is the halo scale radius and C is a function of the halo concentration parameter. Our generalized formalism, in which we treat both energy and momentum injection from starbursts and radiation from the central active galactic nucleus (AGN), allows us to estimate the wind terminal speed to be (4v {sup 2} {sub *} + 6({Gamma} - 1)v {sub .} {sup 2} - 4v {sup 2} {sub s}){sup 1/2}, where {Gamma} is the ratio of force due to radiation pressure to gravity of the central black hole. Our dynamical model also predicts the following: (1) winds from quiescent star-forming galaxies cannot escape from 10{sup 11.5} M {sub Sun} {<=} M{sub h} {<=} 10{sup 12.5} M {sub Sun} galaxies; (2) circumgalactic gas at large distances from galaxies should be present for galaxies in this mass range; (3) for an escaping wind, the wind speed in low- to intermediate-mass galaxies is {approx}400-1000 km s{sup -1}, consistent with observed X-ray temperatures; and (4) winds from massive galaxies with AGNs at Eddington limit have speeds {approx}> 1000 km s{sup -1}. We also find that the ratio [2v {sup 2} {sub *} - (1 - {Gamma})v {sub .} {sup 2}]/v {sup 2} {sub c} dictates the amount of gas lost through winds. Used in conjunction with an appropriate relation between M {sub .} and M{sub h} and an appropriate opacity of dust grains in infrared (K band), this ratio has the attractive property of being minimum at a certain halo mass scale (M{sub h} {approx} 10{sup 12}-10{sup 12.5} M {sub Sun }) that signifies the crossover of AGN domination in outflow properties from starburst activity at lower masses. We find that stellar mass for massive galaxies scales as M {sub *}{proportional_to}M {sup 0.26} {sub h}, and for low-mass galaxies, M {sub *}{proportional_to}M {sup 5/3} {sub h}.

Sharma, Mahavir; Nath, Biman B., E-mail: mahavir@rri.res.in, E-mail: biman@rri.res.in [Raman Research Institute, Sadashiva Nagar, Bangalore 560080 (India)

2013-01-20T23:59:59.000Z

444

Age Dating of a High-Redshift QSO B1422+231 at Z=3.62 and its Cosmological Implications  

E-Print Network [OSTI]

The observed Fe II(UV+optical)/Mg II lambda lambda 2796,2804 flux ratio from a gravitationally lensed quasar B1422+231 at z=3.62 is interpreted in terms of detailed modeling of photoionization and chemical enrichment in the broad-line region (BLR) of the host galaxy. The delayed iron enrichment by Type Ia supernovae is used as a cosmic clock. Our standard model, which matches the Fe II/Mg II ratio, requires the age of 1.5 Gyr for B1422+231 with a lower bound of 1.3 Gyr, which exceeds the expansion age of the Einstein-de Sitter Omega_0=1 universe at a redshift of 3.62 for any value of the Hubble constant in the currently accepted range, H_0=60-80 km,s^{-1},Mpc^{-1}. This problem of an age discrepancy at z=3.62 can be unraveled in a low-density Omega_0<0.2 universe, either with or without a cosmological constant, depending on the allowable redshift range of galaxy formation. However, whether the cosmological constant is a required option in modern cosmology awaits a thorough understanding of line transfer processes in the BLRs.

Yuzuru Yoshii; Takuji Tsujimoto; Kimiaki Kawara

1998-09-04T23:59:59.000Z

445

Type Ia Supernovae Rates and Galaxy Clustering from the CFHT Supernova Legacy Survey  

E-Print Network [OSTI]

The Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS) has created a large homogeneous database of intermediate redshift (0.2 rates, properties, and host galaxy star formation rates. The SNLS SN Ia database has now been combined with a photometric redshift galaxy catalog and an optical galaxy cluster catalog to investigate the possible influence of galaxy clustering on the SN Ia rate, over and above the expected effect due to the dependence of SFR on clustering through the morphology-density relation. We identify three cluster SNe Ia, plus three additional possible cluster SNe Ia, and find the SN Ia rate per unit mass in clusters at intermediate redshifts is consistent with the rate per unit mass in field early-type galaxies and the SN Ia cluster rate from low redshift cluster targeted surveys. We also find the number of SNe Ia in cluster environments to be within a factor of two of expectations from the two component SNIa rate model.

M. L. Graham; C. J. Pritchet; M. Sullivan; S. D. J. Gwyn; J. D. Neill; E. Y. Hsiao; P. Astier; D. Balam; C. Balland; S. Basa; R. G. Carlberg; A. Conley; D. Fouchez; J. Guy; D. Hardin; I. M. Hook; D. A. Howell; R. Pain; K. Perrett; N. Regnault; S. Baumont; J. Le Du; C. Lidman; S. Perlmutter; P. Ripoche; N. Suzuki; E. S. Walker; T. Zhang

2008-01-31T23:59:59.000Z

446

Multi-color light curves of type Ia supernovae on the color-magnitude diagram: A novel step toward more precise distance and extinction estimates  

E-Print Network [OSTI]

Date is earlier than for supernovae with smaller ?m 15 . SeeLight Curves of Type Ia Supernovae on the Color-Magnituderelation of Type Ia supernovae after optical maximum can

Wang, Lifan; Goldhaber, Gerson; Aldering, Greg; Perlmutter, Saul

2003-01-01T23:59:59.000Z

447

Constraining the cosmological parameters with the gas mass fraction in local and z>0.7 Galaxy Clusters  

E-Print Network [OSTI]

We present a study of the baryonic fraction in galaxy clusters aimed at constraining the cosmological parameters Omega_m, Omega_Lambda and the ratio between the pressure and density of the ``dark'' energy, w. We use results on the gravitating mass profiles of a sample of nearby galaxy clusters observed with the BeppoSAX X-ray satellite (Ettori, De Grandi, Molendi 2002) to set constraints on the dynamical estimate of Omega_m. We then analyze Chandra observations of a sample of eight distant clusters with redshift in the range 0.72 and 1.27 and evaluate the geometrical limits on the cosmological parameters Omega_m, Omega_Lambda and w by requiring that the gas fraction remains constant with respect to the look-back time. By combining these two independent probability distributions and using a priori distributions on both Omega_b and H0 peaked around primordial nucleosynthesis and HST-Key Project results respectively, we obtain that, at 95.4 per cent level of confidence, (i) w < -0.49, (ii) Omega_m = 0.34^+0.11_-0.05, Omega_Lambda = 1.30^+0.44_-1.09 for w=-1 (corresponding to the case for a cosmological constant), and (iii) Omega_m = 1-Omega_Lambda = 0.33^+0.07_-0.05 for a flat Universe. These results are in excellent agreement with the cosmic concordance scenario which combines constraints from the power spectrum of the Cosmic Microwave Background, the galaxy and cluster distribution, the evolution of the X-ray properties of galaxy clusters and the magnitude-redshift relation for distant type Ia supernovae. By combining our results with the latter method we further constrain Omega_Lambda =0.94^+0.28_-0.32 and w < -0.89 at the 2 sigma level.

S. Ettori; P. Tozzi; P. Rosati

2003-01-21T23:59:59.000Z

448

A Precision Photometric Comparison between SDSS-II and CSP Type Ia Supernova Data  

E-Print Network [OSTI]

Consistency between Carnegie Supernova Project (CSP) and SDSS-II supernova (SN) survey ugri measurements has been evaluated by comparing SDSS and CSP photometry for nine spectroscopically confirmed Type Ia supernova observed contemporaneously by both programs. The CSP data were transformed into the SDSS photometric system. Sources of systematic uncertainty have been identified, quantified, and shown to be at or below the 0.023 magnitude level in all bands. When all photometry for a given band is combined, we find average magnitude differences of equal to or less than 0.011 magnitudes in ugri, with rms scatter ranging from 0.043 to 0.077 magnitudes. The u band agreement is promising, with the caveat that only four of the nine supernovae are well-observed in u and these four exhibit an 0.038 magnitude supernova-to-supernova scatter in this filter.

Mosher, J; Corlies, L; Folatelli, G; Frieman, J; Holtzman, J; Jha, S W; Kessler, R; Marriner, J; Phillips, M M; Stritzinger, M; Morrell, N; Schneider, D P

2012-01-01T23:59:59.000Z

449

A Cosmology Forecast Toolkit -- CosmoLib  

E-Print Network [OSTI]

The package CosmoLib is a combination of a cosmological Boltzmann code and a simulation toolkit to forecast the constraints on cosmological parameters from future observations. In this paper we describe the released linear-order part of the package. We discuss the stability and performance of the Boltzmann code. This is written in Newtonian gauge and including dark energy perturbations. In CosmoLib the integrator that computes the CMB angular power spectrum is optimized for a $\\ell$-by-$\\ell$ brute-force integration, which is useful for studying inflationary models predicting sharp features in the primordial power spectrum of metric fluctuations. The numerical code and its documentation are available at http://www.cita.utoronto.ca/~zqhuang/CosmoLib.

Zhiqi Huang

2012-06-11T23:59:59.000Z

450

Cosmology of a Lorentz violating Galileon theory  

E-Print Network [OSTI]

We modify the scalar Einstein-aether theory by breaking the Lorentz invariance of a gravitational theory coupled to a Galileon type scalar field. This is done by introducing a Lagrange multiplier term into the action, thus ensuring that the gradient of the scalar field is time-like, with unit norm. The resulting theory is then generally invariant at the level of action, breaking the Lorentz invariance at the level of equations of motion. The theory can also be considered as an extension to the mimetic dark matter theory, by adding some derivative self interactions to the action, which keeps the equations of motion at most second order in time derivatives. The cosmological implications of the model are discussed in detail. In particular, we show that a matter dominated (dust) universe experiences a late time acceleration. The cosmological implications of a special coupling between the scalar field and the trace of the energy-momentum tensor are also explored.

Haghani, Zahra; Sepangi, Hamid Reza; Shahidi, Shahab

2015-01-01T23:59:59.000Z

451

Nonsingular Decaying Vacuum Cosmology and Entropy Production  

E-Print Network [OSTI]

The thermodynamic behavior of a decaying vacuum cosmology describing the entire cosmological history evolving between two extreme (early and late time) de Sitter eras is investigated. The thermal evolution from the early de Sitter to the radiation phase is discussed in detail. The temperature evolution law and the increasing entropy function are analytically determined. The entropy of the effectively massless particles is initially zero but evolves continuously to the present day maximum value within the current Hubble radius, $S_0 \\sim 10^{88}$ in natural units. By using the Gibbons-Hawking temperature relation for the de Sitter spacetime, it is found that the ratio between the primeval and the late time vacuum energy densities is $\\rho_{vI}/\\rho_{v0} \\sim 10^{123}$, as required by some naive estimates from quantum field theory.

J. A. S. Lima; S. Basilakos; Joan Solŕ

2015-03-08T23:59:59.000Z

452

Collection: Supernova Simulations from the T-6 Group at Los Alamos National  

Office of Scientific and Technical Information (OSTI)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartmentNationalRestart ofMeasuring DopamineEnergy,6. RadiativeLaboratory (LANL) | DOE Data

453

Cosmological Perturbations with Multiple Scalar Fields  

E-Print Network [OSTI]

In this brief note we present a set of equations describing the evolution of perturbed scalar fields in a cosmological spacetime with multiple scalar fields. We take into account of the simultaneously excited full metric perturbations in the context of the uniform-curvature gauge which is known to be the best choice. The equations presented in a compact form will be useful for handling the structure formation processes under the multiple episodes of inflation.

J. Hwang

1996-08-08T23:59:59.000Z

454

Physical space and cosmology. I: Model  

E-Print Network [OSTI]

The nature of the physical space seems the most important subject in physics. A present paper proceeds from the assumption of physical reality of space contrary to the standard view of the space as a purely relational nonexistence - void. The space and its evolution are the primary sources of phenomena in Mega- and micro-worlds. Thus cosmology and particle physics have the same active agent - physical space.

Valeriy P. Polulyakh

2011-02-01T23:59:59.000Z

455

The Construction of Sudden Cosmological Singularities  

E-Print Network [OSTI]

Solutions of the Friedmann-Lemaitre cosmological equations of general relativity have been found with finite-time singularities that are everywhere regular, have regular Hubble expansion rate, and obey the strong-energy conditions but possess pressure and acceleration singularities at finite time that are not associated with geodesic incompleteness. We show how these solutions with sudden singularities can be constructed using fractional series methods and find the limiting form of the equation of state on approach to the singularity.

John D. Barrow; S. Cotsakis; A. Tsokaros

2010-03-04T23:59:59.000Z

456

Simple Cosmological Model with Relativistic Gas  

E-Print Network [OSTI]

We construct simple and useful approximation for the relativistic gas of massive particles. The equation of state is given by an elementary function and admits analytic solution of the Friedmann equation, including more complex cases when the relativistic gas of massive particles is considered together with radiation or with dominating cosmological constant. The model of relativistic gas may be interesting for the description of primordial Universe, especially as a candidate for the role of a Dark Matter.

Guilherme de Berredo-Peixoto; Ilya L. Shapiro; Flavia Sobreira

2005-06-16T23:59:59.000Z

457

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

E-Print Network [OSTI]

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

R. C. Gupta

2004-12-07T23:59:59.000Z

458

Polarisation spectral synthesis for Type Ia supernova explosion models  

E-Print Network [OSTI]

We present a Monte Carlo radiative transfer technique for calculating synthetic spectropolarimetry for multi-dimensional supernova explosion models. The approach utilises "virtual-packets" that are generated during the propagation of the Monte Carlo quanta and used to compute synthetic observables for specific observer orientations. Compared to extracting synthetic observables by direct binning of emergent Monte Carlo quanta, this virtual-packet approach leads to a substantial reduction in the Monte Carlo noise. This is vital for calculating synthetic spectropolarimetry (since the degree of polarisation is typically very small) but also useful for calculations of light curves and spectra. We first validate our approach via application of an idealised test code to simple geometries. We then describe its implementation in the Monte Carlo radiative transfer code ARTIS and present test calculations for simple models for Type Ia supernovae. Specifically, we use the well-known one-dimensional W7 model to verify tha...

Bulla, M; Kromer, M

2015-01-01T23:59:59.000Z

459

Galactic Cosmic Ray Origin Sites: Supernova Remnants and Superbubbles  

E-Print Network [OSTI]

We discuss processes in galactic cosmic ray (GCR) acceleration sites - supernova remnants, compact associations of young massive stars, and superbubbles. Mechanisms of efficient conversion of the mechanical power of the outflows driven by supernova shocks and fast stellar winds of young stars into magnetic fields and relativistic particles are discussed. The high efficiency of particle acceleration in the sources implies the importance of nonlinear feedback effects in a symbiotic relationship where the magnetic turbulence required to accelerate the CRs is created by the accelerated CRs themselves. Non-thermal emission produced by relativistic particles (both those confined in and those that escape from the cosmic accelerators) can be used to constrain the basic physical models of the GCR sources. High resolution X-ray synchrotron imaging, combined with GeV-TeV gamma ray spectra, is a powerful tool to probe the maximum energies of accelerated particles. Future MeV regime spectroscopy will provide unique inform...

Bykov, A M; Gladilin, P E; Osipov, S M; 10.1063/1.4772219

2012-01-01T23:59:59.000Z

460

Towards a Synthesis of Core-Collapse Supernova Theory  

E-Print Network [OSTI]

New insights into the mechanism and character of core--collapse supernova explosions are transforming the approach of theorists to their subject. The universal realization that the direct hydrodynamic mechanism does not work and that a variety of hydrodynamic instabilities can influence the viability of theoretical explosions has ushered in a new era in supernova modeling. In this paper, I discuss the important physical and technical issues that remain. I review the neutrino--driven mechanism, the possible roles of Rayleigh--Taylor instabilities, questions in neutrino transport, and the various observational constraints within which theorists must operate. However, a consensus has yet to be achieved among active workers concerning many important details and some essential phenomenology. This synopsis is meant to accomplish two things: 1) to focus attention on the interesting problems whose resolution will bring needed progress, and 2) to assess the current status of the theoretical art.

Adam Burrows

1996-06-06T23:59:59.000Z

Note: This page contains sample records for the topic "group supernova cosmology" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.