Abstract
We study the observational consequences of several unknown properties of Population III stars using large-scale cosmological simulations that include a subgrid model to track the unresolved mixing of pollutants. Varying the value of the critical metallicity that marks the boundary between Population III and Population II star formation across 2 dex has a negligible effect on the fraction of Population III stars formed and the subsequent fraction of Population III flux from high-redshift galaxies. However, adopting a lognormal initial mass function (IMF) for Population III stars, in place of a baseline Salpeter IMF, results in a Population III star formation rate density that is 1/4 of the baseline rate. The flux from high-redshift galaxies modeled with this IMF is highly bimodal, resulting in a tiny fraction of z ≤ 8 galaxies with more than 75% of their flux coming from Population III stars. However, at z = 9, right before reionization in our simulations, ≈20% of galaxies are Population III-bright with m UV ≤ 31.4 mag, and at least 75% of their flux is generated by Population III stars. Additionally, the lognormal Population III IMF results in a population of carbon-enhanced, metal-poor stars in reasonable agreement with MW halo observations. Our analysis supports the conclusion that the Population III IMF was dominated by stars in the 20-120 M ⊙ range that generate supernovae with carbon-enhanced ejecta.
Original language | English (US) |
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Article number | 206 |
Journal | Astrophysical Journal |
Volume | 871 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1 2019 |
Keywords
- Population III
- cosmology: Theory
- early universe
- evolution
- galaxies: High-redshift
- stars: Formation
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science