scholarly journals Supernova Nucleosynthesis in the early universe

2008 ◽  
Vol 4 (S255) ◽  
pp. 189-193
Author(s):  
Nozomu Tominaga ◽  
Hideyuki Umeda ◽  
Keiichi Maeda ◽  
Ken'ichi Nomoto ◽  
Nobuyuki Iwamoto
Keyword(s):  
Early Universe ◽  
Chemical Evolution ◽  
Energy Deposition ◽  
Main Sequence ◽  
Metal Enrichment ◽  
Deposition Rates ◽  
Abundance Patterns ◽  
History Of ◽  
The Universe

AbstractThe first metal enrichment in the universe was made by supernova (SN) explosions of population (Pop) III stars. The history of chemical evolution is recorded in abundance patterns of extremely metal-poor (EMP) stars. We investigate the properties of nucleosynthesis in Pop III SNe by comparing their yields with the abundance patterns of the EMP stars. We focus on (1) jet-induced SNe with various properties of the jets, especially energy deposition rates [Ėdep = (0.3 − 1500) × 1051 ergs s−1], and (2) SNe of stars with various main-sequence masses (Mms = 13 − 50M⊙) and explosion energies [E = (1 − 40) × 1051ergs]. The varieties of Pop III SNe can explain the observations of the EMP stars: (1) higher [C/Fe] for lower [Fe/H] and (2) trends of abundance ratios [X/Fe] against [Fe/H].

scholarly journals Displaced new physics at colliders and the early universe before its first second

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Lorenzo Calibbi ◽  
Francesco D’Eramo ◽  
Sam Junius ◽  
Laura Lopez-Honorez ◽  
Alberto Mariotti
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Upper Bound ◽  
New Physics ◽  
Early History ◽  
Relic Density ◽  
History Of ◽  
Indirect Information ◽  
The Universe

Abstract Displaced vertices at colliders, arising from the production and decay of long-lived particles, probe dark matter candidates produced via freeze-in. If one assumes a standard cosmological history, these decays happen inside the detector only if the dark matter is very light because of the relic density constraint. Here, we argue how displaced events could very well point to freeze-in within a non-standard early universe history. Focusing on the cosmology of inflationary reheating, we explore the interplay between the reheating temperature and collider signatures for minimal freeze-in scenarios. Observing displaced events at the LHC would allow to set an upper bound on the reheating temperature and, in general, to gather indirect information on the early history of the universe.

scholarly journals Quasi-Steady State Cosmology

1994 ◽  
Vol 159 ◽  
pp. 293-299
Author(s):  
G. Burbidge ◽  
F. Hoyle ◽  
J.V. Narlikar
Keyword(s):  
Steady State ◽  
Early Universe ◽  
Particle Physics ◽  
Physical Theory ◽  
Big Bang ◽  
Quasi Steady State ◽  
Recent Developments ◽  
History Of ◽  
The Big Bang ◽  
The Universe

The standard big bang cosmology has the universe created out of a primeval explosion that not only created matter and radiation but also spacetime itself. The big bang event itself cannot be discussed within the framework of a physical theory but the events following it are in principle considered within the scope of science. The recent developments on the frontier between particle physics and cosmology highlight the attempts to chart the history of the very early universe.

scholarly journals The emergence of the first star-free atomic cooling haloes in the Universe

2020 ◽  
Vol 492 (2) ◽  
pp. 3021-3031 ◽  
Author(s):  
John A Regan ◽  
John H Wise ◽  
Brian W O’Shea ◽  
Michael L Norman
Keyword(s):  
Black Hole ◽  
Early Universe ◽  
Metal Enrichment ◽  
Massive Black Hole ◽  
Metal Free ◽  
Physical Conditions ◽  
Radiation Fields ◽  
Atomic Cooling ◽  
The Universe ◽  
Massive Galaxy

ABSTRACT Using the Renaissance suite of simulations, we examine the emergence of pristine atomic cooling haloes that are both metal free and star free in the early universe. The absence of metals prevents catastrophic cooling, suppresses fragmentation, and may allow for the formation of massive black hole seeds. Here we report on the abundance of pristine atomic cooling haloes found and on the specific physical conditions that allow for the formation of these direct-collapse-black hole (DCBH) haloes. In total, in our simulations we find that 79 DCBH haloes form before a redshift of 11.6. We find that the formation of pristine atomic haloes is driven by the rapid assembly of the atomic cooling haloes with mergers, both minor and/or major, prior to reaching the atomic cooling limit a requirement. However, the ability of assembling haloes to remain free of (external) metal enrichment is equally important and underlines the necessity of following the transport of metals in such simulations. The candidate DCBH-hosting haloes we find have been exposed to mean Lyman–Werner radiation fields of J21 ∼1 and typically lie at least 10 kpc (physical) from the nearest massive galaxy. The growth rates of the haloes reach values of greater than 107$\rm {M_{\odot }}~$ per unit redshift, leading to significant dynamical heating and the suppression of efficient cooling until the halo crosses the atomic cooling threshold. Finally, we also find five synchronized halo candidates where pairs of pristine atomic cooling haloes emerge that are both spatially and temporally synchronized.

scholarly journals Modelling the Chemical Evolution

2009 ◽  
Vol 5 (S265) ◽  
pp. 325-335
Author(s):  
Gerhard Hensler ◽  
Simone Recchi
Keyword(s):  
Chemical Evolution ◽  
Metal Enrichment ◽  
Element Abundances ◽  
Chemical Enrichment ◽  
Direct Observations ◽  
Trace Back ◽  
Astrophysical Objects ◽  
The One ◽  
The Universe ◽  
Insight Into

AbstractAdvanced observational facilities allow to trace back the chemical evolution of the Universe, on the one hand, from local objects of different ages and, secondly, by direct observations of redshifted objects. The chemical enrichment serves as one of the cornerstones of cosmological evolution. In order to understand this chemical evolution in morphologically different astrophysical objects models are constructed based on analytical descriptions or numerical methods. For the comparison of their chemical issues, as there are element abundances, gradients, and ratios, with observations not only the present-day values are used but also their temporal evolution from the first era of metal enrichment. Here we will provide some insight into basics of chemical evolution models, highlight advancements, and discuss a few applications.

scholarly journals The Connection between Gamma-Ray Bursts and Extremely Metal-Poor Stars as Nucleosynthetic Probes of the Early Universe

2007 ◽  
Vol 3 (S250) ◽  
pp. 463-470
Author(s):  
K. Nomoto ◽  
N. Tominaga ◽  
M. Tanaka ◽  
K. Maeda ◽  
H. Umeda
Keyword(s):  
Early Universe ◽  
Energy Deposition ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Continuous Series ◽  
Core Collapse ◽  
Relativistic Jets ◽  
X Ray ◽  
Abundance Patterns ◽  
Energy Deposition Rate

AbstractThe connection between the long GRBs and Type Ic Supernovae (SNe) has revealed the interesting diversity: (i) GRB-SNe, (ii) Non-GRB Hypernovae (HNe), (iii) X-Ray Flash (XRF)-SNe, and (iv) Non-SN GRBs (or dark HNe). We show that nucleosynthetic properties found in the above diversity are connected to the variation of the abundance patterns of extremely-metal-poor (EMP) stars, such as the excess of C, Co, Zn relative to Fe. We explain such a connection in a unified manner as nucleosynthesis of hyper-aspherical (jet-induced) explosions of Pop III core-collapse SNe. We show that (1) the explosions with large energy deposition rate, Ėdep, are observed as GRB-HNe and their yields can explain the abundances of normal EMP stars, and (2) the explosions with small Ėdepare observed as GRBs without bright SNe and can be responsible for the formation of the C-rich EMP (CEMP) and the hyper metal-poor (HMP) stars. We thus propose that GRB-HNe and the Non-SN GRBs (dark HNe) belong to a continuous series of BH-forming massive stellar deaths with the relativistic jets of different Ėdep.

scholarly journals Exploring the early Universe with extremely metal-poor stars

2015 ◽  
Vol 11 (S317) ◽  
pp. 64-68
Author(s):  
Terese T. Hansen ◽  
Norbert Christlieb ◽  
Camilla J. Hansen ◽  
Timothy C. Beers
Keyword(s):  
Early Universe ◽  
Chemical Evolution ◽  
Large Fraction ◽  
Abundance Patterns ◽  
Broad Variety ◽  
Low Metallicity

AbstractThe earliest phases of Galactical chemical evolution and nucleosynthesis can be investigated by studying the old metal-poor stars. It has been recognized that a large fraction of metal-poor stars possess significant over-abundances of carbon relative to iron. Here we present the results of a 23-star homogeneously analyzed sample of metal-poor candidates from the Hamburg/ESO survey. We have derived abundances for a large number of elements ranging from Li to Pb. The sample includes four ultra metal-poor stars ([Fe/H] < −4.0), six CEMP-no stars, five CEMP-s stars, two CEMP-r stars and two CEMP-r/s stars. This broad variety of the sample stars gives us an unique opportunity to explore different abundance patterns at low metallicity.

Deviations of R2 cosmology from the Einstein’s General Relativity

2020 ◽  
Vol 35 (36) ◽  
pp. 2044026
Author(s):  
E. V. Arbuzova
Keyword(s):  
General Relativity ◽  
Early Universe ◽  
Significant Influence ◽  
Particle Production ◽  
Cosmological Evolution ◽  
Evolution Of The Universe ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Einstein’S General Relativity

The cosmological history of the universe in the [Formula: see text] gravity is studied starting from the “very beginning” up to the present time. The primordial inflationary expansion of the universe is considered and it is shown that the gravitational particle production by the oscillating curvature, [Formula: see text], led to a consistent transition to the Friedmann cosmology, but the cosmological evolution in the early universe strongly differed from the standard one. It is shown that the effects of gravitational production of particles had a significant influence on the evolution of the universe.

scholarly journals UNAVOIDABLE CMB SPECTRAL FEATURES AND BLACKBODY PHOTOSPHERE OF OUR UNIVERSE

2013 ◽  
Vol 22 (07) ◽  
pp. 1330014 ◽  
Author(s):  
RASHID A. SUNYAEV ◽  
RISHI KHATRI
Keyword(s):  
Energy Spectrum ◽  
Early Universe ◽  
Resonant Scattering ◽  
Spectral Features ◽  
Next Generation ◽  
Physical Processes ◽  
Cosmological Recombination ◽  
History Of ◽  
The Universe ◽  
Type Intermediate

Spectral features in the CMB energy spectrum contain a wealth of information about the physical processes in the early Universe, z ≲ 2 × 106. The CMB spectral distortions are complementary to all other probes of cosmology. In fact, most of the information contained in the CMB spectrum is inaccessible by any other means. This review outlines the main physics behind the spectral features in the CMB throughout the history of the Universe, concentrating on the distortions which are inevitable and must be present at a level observable by the next generation of proposed CMB experiments. The spectral distortions considered here include spectral features from cosmological recombination, resonant scattering of CMB by metals during reionization which allows us to measure their abundances, y-type distortions during and after reionization and μ-type and i-type (intermediate between μ and y) distortions created at redshifts z ≳ 1.5 × 104.

scholarly journals Theoretical stellar ΔY/ΔO in the early Universe

2009 ◽  
Vol 5 (S268) ◽  
pp. 447-452
Author(s):  
Sylvia Ekström ◽  
Georges Meynet ◽  
André Maeder ◽  
Cristina Chiappini ◽  
Cyril Georgy ◽  
...  
Keyword(s):  
Early Universe ◽  
Chemical Evolution ◽  
Point Of View ◽  
Theoretical Point ◽  
Chemical Enrichment ◽  
Low Metallicity ◽  
Stellar Models ◽  
Population Iii Stars ◽  
The Universe ◽  
Population Iii

AbstractPopulation III stars initiated the chemical enrichment of the Universe. Chemical evolution models seem to favour fast rotators among the very low-metallicity population. When a star rotates fast, it ejects significant quantities of He and its nucleosynthesic products are modified compared to the case without rotation. The value of ΔY/ΔO is explored from a theoretical point of view through stellar models of zero- or very low-metallicity.

scholarly journals The Thermal History of the Universe and the Spectrum of Relic Radiation

1974 ◽  
Vol 63 ◽  
pp. 167-173
Author(s):  
R. A. Sunyaev
Keyword(s):  
Energy Release ◽  
Early Universe ◽  
Thermal History ◽  
Energy Production ◽  
Cosmological Models ◽  
Clear Picture ◽  
Evolution Of The Universe ◽  
Strong Turbulence ◽  
History Of ◽  
The Universe

Many of the cosmological models currently under discussion and theories of the origin of galaxies which involve antimatter, strong turbulence and so on result in significant energy release during the evolution of the Universe. It is evident that significant energy production should lead to distortions of the spectrum of the relic radiation. The absence of noticeable deviations from the Planckian spectrum enables us to set limits to the energy release in the early Universe (102 < z< 108). But in order to have a clear picture of possible distortions, let us first review the idealized situation.

Sign in / Sign up

Export Citation Format

Share Document