scholarly journals The search for Population III stars

2008 ◽  
Vol 4 (S255) ◽  
pp. 75-78 ◽  
Author(s):  
Sperello di Serego Alighieri ◽  
Jaron Kurk ◽  
Benedetta Ciardi ◽  
Andrea Cimatti ◽  
Emanuele Daddi ◽  
...  
Keyword(s):  
First Generation ◽  
Dwarf Galaxy ◽  
Big Bang ◽  
Metal Enrichment ◽  
Promising Candidate ◽  
Population Iii Stars ◽  
The Universe ◽  
Population Iii

AbstractPopulation III stars, the first generation of stars formed from primordial Big Bang material with a top–heavy IMF, should contribute substantially to the Universe reionization and they are crucial for understanding the early metal enrichment of galaxies. Therefore it is very important that these objects, foreseen by theories, are detected by observations. However PopIII stars, searched through the HeII 1640Å line signature, have remained elusive. We report about the search for the HeII line in a galaxy at z = 6.5, which is a very promising candidate. Unfortunately we are not yet able to show the results of this search. However we call attention to the possible detection of PopIII stars in a lensed HII dwarf galaxy at z = 3.4, which appeared in the literature some years ago, but has been overlooked.

scholarly journals The stochastic enrichment of Population II stars

2020 ◽  
Vol 500 (4) ◽  
pp. 5214-5228
Author(s):  
Louise Welsh ◽  
Ryan Cooke ◽  
Michele Fumagalli
Keyword(s):  
First Generation ◽  
Milky Way ◽  
Systematic Errors ◽  
Chemical Abundances ◽  
Chemical Enrichment ◽  
Halo Stars ◽  
Chemical Products ◽  
Population Iii Stars ◽  
Intrinsic Scatter ◽  
Population Iii

ABSTRACT We investigate the intrinsic scatter in the chemical abundances of a sample of metal-poor ([Fe/H] < −2.5) Milky Way halo stars. We draw our sample from four historic surveys and focus our attention on the stellar Mg, Ca, Ni, and Fe abundances. Using these elements, we investigate the chemical enrichment of these metal-poor stars using a model of stochastic chemical enrichment. Assuming that these stars have been enriched by the first generation of massive metal-free stars, we consider the mass distribution of the enriching population alongside the stellar mixing and explosion energy of their supernovae. For our choice of stellar yields, our model suggests that the most metal-poor stars were enriched, on average, by $\hat{N}_{\star }=5^{+13}_{-3}~(1\sigma)$ Population III stars. This is comparable to the number of enriching stars inferred for the most metal-poor DLAs. Our analysis therefore suggests that some of the lowest mass structures at z ∼ 3 contain the chemical products from < 13(2σ) Population III enriched minihaloes. The inferred IMF is consistent with that of a Salpeter distribution and there is a preference towards ejecta from minimally mixed hypernovae. However, the estimated enrichment model is sensitive to small changes in the stellar sample. An offset of ∼ 0.1 dex in the [Mg/Ca] abundance is shown to be sensitive to the inferred number of enriching stars. We suggest that this method has the potential to constrain the multiplicity of the first generation of stars, but this will require: (1) a stellar sample whose systematic errors are well understood; and, (2) documented uncertainties associated with nucleosynthetic yields.

scholarly journals Star Forming Galaxies at z > 5

2007 ◽  
Vol 3 (S250) ◽  
pp. 429-436
Author(s):  
Yoshi Taniguchi
Keyword(s):  
Recent Progress ◽  
Near Infrared ◽  
Wide Field ◽  
Optical Window ◽  
Star Forming ◽  
Deep Imaging ◽  
Star Formation Activity ◽  
Population Iii Stars ◽  
The Universe ◽  
Population Iii

AbstractWe present recent progress in searching for galaxies at redshift from z ≃ 5 to z ∼ 10. Wide-field and sensitive surveys with 8m class telescopes have been providing more than several hundreds of star forming galaxies at z ∼ 5 − 7 that are probed in the optical window. These galaxies are used to study the early cosmic star formation activity as well as the early structure formation in the universe. Moreover, near infrared deep imaging and spectroscopic surveys have found probable candidates of galaxies from z ∼ 7 to z ∼ 10. Although these candidates are too faint to be identified unambiguously, we human being are now going to the universe beyond 13 billion light years, close to the epoch of first-generations stars; i.e., Population III stars. We also mention about challenges to find Population III-dominated galaxies in the early universe.

scholarly journals Evolution of virial clouds-I: from surface of last scattering up to the formation of population-III stars

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Noraiz Tahir ◽  
Asghar Qadir ◽  
Muhammad Sakhi ◽  
Francesco De Paolis
Keyword(s):  
Observational Data ◽  
First Generation ◽  
Cloud Formation ◽  
Standard Theory ◽  
Rotational Axis ◽  
Population Iii Stars ◽  
Temperature Asymmetry ◽  
Cmb Temperature ◽  
Population Iii

AbstractThe analysis of WMAP and Planck CMB data has shown the presence of temperature asymmetries towards the halos of several galaxies, which is probably due to the rotation of clouds present in these halos about the rotational axis of the galaxies. It had been proposed that these are hydrogen clouds that should be in equilibrium with the CMB. However, standard theory did not allow equilibrium of such clouds at the very low CMB temperature, but it was recently shown that the equilibrium could be stable. This still does not prove that the cloud concentration and that the observed temperature asymmetry is due to clouds in equilibrium with the CMB. To investigate the matter further, it would be necessary to trace the evolution of such clouds, which we call “virial clouds”, from their formation epoch to the present, so as to confront the model with the observational data. The task is to be done in two steps: (1) from the cloud formation before the formation of first generation of stars; (2) from that time to the present. In this paper we deal with the first step leaving the second one to a subsequent analysis.

Nonbaryonic Dark Matter

2020 ◽  
pp. 279-299
Author(s):  
P. J. E. Peebles
Keyword(s):  
Dark Matter ◽  
Cosmological Model ◽  
Early Universe ◽  
Particle Physics ◽  
First Generation ◽  
Mass Density ◽  
Rest Mass ◽  
Big Bang ◽  
Expansion Of The Universe ◽  
The Universe

This chapter discusses the particle physicists' considerations of nonbaryonic matter. It takes into account the condition that if this nonbaryonic matter were produced in the hot early stages of expansion of the universe, then its remnant mass density must not exceed that allowed by the relativistic big bang cosmological model (again, assuming the relativistic theory). But it is notable that cosmologists took over the notion of nonbaryonic dark matter before the particle physics community had taken much interest in the astronomers' evidence of the presence of subluminal matter. The nonbaryonic dark matter most broadly discussed in the 1980s came in two varieties, cold and hot. The latter would be one of the known class of neutrinos with rest mass of a few tens of electron volts. The initially hot (meaning rapidly streaming) neutrinos in the early universe would have smoothed the mass distribution, and that smoothing would have tended to cause the first generation of structure to be massive systems that must have fragmented to form galaxies.

scholarly journals Constraints on the Dark Matter

1987 ◽  
Vol 117 ◽  
pp. 410-410
Author(s):  
B. J. Carr
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Neutron Stars ◽  
Gravitational Lensing ◽  
White Dwarfs ◽  
Big Bang ◽  
Galactic Halos ◽  
M Dwarfs ◽  
Population Iii Stars ◽  
Population Iii

There is evidence for four types of dark matter: (1) the local d.m. in the galactic disc; (2) the d.m. associated with galactic halos; (3) the d.m. in clusters; and (4) a background closure density of d.m. required if the Universe undergoes an inflationary phase. There are three types of explanation: (1) remnants of a first generation of Population III stars, including black holes (SMOs, VMOs or MOs), neutron stars, white dwarfs, or LMOs (M-dwarfs and Jupiters); (2) elementary particle relicts of the Big Bang (inos), usefully classified - according to their mass - as hot, warm, or cold, since this determines the scale on which they can cluster; and (3) primordial black holes, formed from density perturbations or phase transitions in the early Universe. Various constraints on the d.m. candidates are indicated by the shaded regions in the Figure below. The conventional model of cosmological nucleosynthesis precludes Population III remnants providing the closure and perhaps cluster d.m., while stellar nucleosynthesis constraints preclude neutron stars from explaining anything and allow white dwarfs to provide only the local d.m. Source counts exclude M-dwarfs from providing the local or halo d.m., while gravitational lensing effects exclude SMOs larger than 108M⊙ from explaining anything and LMOs or VMOs from having the closure density. Dynamical considerations imply M<2M⊙ for the local d.m., M<106M⊙ for the halo d.m., and M<109M⊙ for the cluster d.m.; they also imply that the local d.m. cannot be inos and that the halo d.m. cannot be a hot ino. The table suggests the following conclusions: (1) no single candidate can explain all four d.m. problems; (2) the best candidate for the closure d.m. is an ino; (3) the best candidates for the local d.m. are white dwarfs or Jupiters; (4) the halo (and possibly cluster) d.m. could plausibly be black holes or Jupiters.

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 Does the structure of Population III supernova ejecta affect the elemental abundance of extremely metal-poor stars?

2020 ◽  
Vol 498 (2) ◽  
pp. 2676-2687
Author(s):  
Gen Chiaki ◽  
Nozomu Tominaga
Keyword(s):  
First Generation ◽  
Abundance Ratio ◽  
Mass Scale ◽  
Elemental Abundance ◽  
Abundance Pattern ◽  
Normal Core ◽  
Structure Of Population ◽  
Population Iii Stars ◽  
The One ◽  
Population Iii

ABSTRACT The first generation of metal-free (Population III) stars are crucial for the production of heavy elements in the earliest phase of structure formation. Their mass scale can be derived from the elemental abundance pattern of extremely metal-poor (EMP) stars, which are assumed to inherit the abundances of uniformly mixed supernova (SN) ejecta. If the expanding ejecta maintains its initial stratified structure, the elemental abundance pattern of EMP stars might be different from that from uniform ejecta. In this work, we perform numerical simulations of the metal enrichment from stratified ejecta for normal core-collapse SNe (CCSNe) with a progenitor mass $25 \ {\rm M_{\bigodot }}$ and explosion energies 0.7–10 B ($1 \ {\rm B} = 10^{51} \ \rm erg$). We find that SN shells fall back into the central minihalo in all models. In the recollapsing clouds, the abundance ratio [M/Fe] for stratified ejecta is different from the one for uniform ejecta only within ±0.4 dex for any element M. We also find that, for the largest explosion energy (10 B), a neighbouring halo is also enriched. Only the outer layers containing Ca or lighter elements reach the halo, where [C/Fe] = 1.49. This means that C-enhanced metal-poor stars can form from the CCSN even with an average abundance ratio [C/Fe] = −0.65.

Survival of Population III stars

2018 ◽  
Vol 14 (S342) ◽  
pp. 266-267
Author(s):  
Jayanta Dutta ◽  
Sharanya Sur ◽  
Athena Stacy ◽  
Jasjeet Singh Bagla
Keyword(s):  
Main Sequence ◽  
Milky Way ◽  
Core Collapse ◽  
Escape Velocity ◽  
First Stars ◽  
Present Epoch ◽  
Final Mass ◽  
Population Iii Stars ◽  
The Universe ◽  
Population Iii

AbstractIn our earlier studyDutta (2016a), it has been shown that a number of primordial protostars (the ‘first stars’ in the Universe, also known as Population III or Pop III stars) are being ejected from the cluster of their origin with the velocity exceeding their escape velocity. Hence there is possibility that some of these protostars can enter main sequence and survive till present epoch, even in Milky Way. We ask the question if the protostars can avoid core collapse, and stop accreting before being ejected from the cluster, with the final mass of stars as 0.8 Mȯ.

scholarly journals Big Bang Nucleosynthesis, Population III, and Stellar Genetics in the Galactic Halo

2002 ◽  
Vol 19 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Sean G. Ryan
Keyword(s):  
Galactic Halo ◽  
Stellar Populations ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Chemical Signatures ◽  
The Galaxy ◽  
Successive Generations ◽  
The Big Bang ◽  
The Universe ◽  
Population Iii

AbstractThe diverse isotopic and elemental signatures produced in different nucleosynthetic sites are passed on to successive generations of stars. By tracing these chemical signatures back through the stellar populations of the Galaxy, it is possible to unravel its nucleosynthetic history and even to study stars which are now extinct. This review considers recent applications of ‘stellar genetics’ to examine the earliest episodes of nucleosynthesis in the universe, in Population iii stars and the Big Bang.

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