Early chemical enrichment of the universe and the role of very massive pop III stars

Abstract

In this paper the role of very massive pop III stars in the chemical enrichment of the early universe is discussed. We first compare our predictions with the abundance ratios measured in the high redshift Lyman-alpha forest to check whether they are compatible with the values predicted by assuming that the early universe was enriched by massive pop III stars. We conclude that to explain the observed C/Si ratio in the intergalactic medium, a contribution from pop II stars to carbon enrichment is necessary, already at redshift z=5. We then evaluate the number of Pair-Instability Supernovae (SN_(gamma gamma)) required to enrich the universe to the critical metallicity Z_cr, i.e. the metallicity value which causes the transition from a very massive star regime (m > 100 M_sun) to a lower mass regime, similar to the one characteristic of the present time (m < 100 M_sun). It is found that between 110 and 115 SN_(gamma gamma) are sufficient to chemically enrich a cubic megaparsec of the intergalactic medium at high redshift for a variety of initial mass functions. The number of ionizing photons provided by these SN_(gamma gamma) and also by the pop III stars ending as black holes was computed and we conclude that there are not enough photons to reionize the universe, being down by at least a factor of ~ 3. Finally, we calculate the abundance ratios generated by pop III stars and compare it with the ones observed in low metallicity Damped Lyman-alpha systems (DLAs). We suggest that pop III stars alone cannot be responsible for the abundance ratios in these objects and that intermediate mass pop II stars must have played an important role especially in enriching DLAs in nitrogen.

8 pages, 2 figures, MNRAS, accepted for publication - typos corrected

References in corpus (12)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• How Massive Single Stars End their Life
• The First Stars
• Metallicity of the intergalactic medium using pixel statistics. II. The distribution of metals as traced by C IV
• Explosive yields of massive stars from Z=0 to Z=Zsun
• The Universe Was Reionized Twice
• Oxygen, Carbon and Nitrogen evolution in galaxies
• Early Reionization by the First Galaxies
• Implications of WMAP Observations On the Population III Star Formation Processes
• The Abundances of Nitrogen and Oxygen in Damped Lyman Alpha Systems
• A comprehensive set of elemental abundances in damped Ly-alpha systems: revealing the nature of these high-redshift galaxies
• Chemical evolution and nature of Damped Lyman-Alpha systems

Cited by in corpus (21)

• Bright OB stars in the Galaxy - III. Constraints on the radial stratification of the clumping factor in hot star winds from a combined Halpha, IR and radio analysis
• Two populations of metal-free stars in the early Universe
• SN 2005cs in M51 I. The first month of evolution of a subluminous SN II plateau
• Identification of the Red Supergiant Progenitor of Supernova 2005cs: Do the Progenitors of Type II-P Supernovae Have Low Mass?
• The First Supernova Explosions: Energetics, Feedback, and Chemical Enrichment
• The recycling of gas and metals in galaxy formation: predictions of a dynamical feedback model
• An inhomogeneous model for the Galactic halo: a possible explanation for the spread observed in s- and r-process elements
• Core-Collapse Very Massive Stars: Evolution, Explosion, and Nucleosynthesis of Population III 500 -- 1000 $M_{\odot }$ Stars
• AG Carinae: a Luminous Blue Variable with a high rotational velocity
• Chemical enrichment of Damped Lyman Alpha systems as a direct constraint on Population III star formation
• The most metal-poor damped Ly alpha system at z<3: constraints on early nucleosynthesis
• The stellar metallicity distribution of disc galaxies and bulges in cosmological simulations
• Structures and components in galaxy clusters: observations and models
• The nature of NV absorbers at high redshift
• Hot Cores : Probes of High-Redshift Galaxies
• The origin of the chemical elements in cluster cores
• Potential signature of Population III pair-instability supernova ejecta in the BLR gas of the most distant quasar at z = 7.54
• Cosmic evolution of metal densities: the enrichment of the Inter-Galactic Medium
• Astrophysics in 2005
• Potential contributions of Pop III and intermediate-mass Pop II stars to cosmic chemical enrichment
• CHEERS: Future perspectives for abundance measurements in clusters with XMM-Newton