Abstract
Recent high-resolution simulations of early structure formation have
shown that externally enriched halos may form some of the first
metal-enriched stars. This study utilizes a 1 comoving Mpc3 high-resolution simulation to study the enrichment process of metal-enriched halos down to z
= 9.3. Our simulation uniquely tracks the metals ejected from
Population III stars, and we use this information to identify the origin
of metals within metal-enriched halos. These halos show a wide range of
metallicities, but we find that the source of metals for 50%
of metal-enriched halos is supernova explosions of Population III stars
occurring outside their virial radii. The results presented here
indicate that external enrichment by metal-free stars dominates the
enrichment process of halos with virial mass below 106 M⊙ down to z
= 9.3. Despite the prevalence of external enrichment in low-mass halos,
Population II stars forming due to external enrichment are rare because
of the small contribution of low-mass halos to the global star
formation rate combined with low metallicities toward the center of
these halos resulting from metal ejecta from external sources mixing
from the outside in. The enriched stars that do form through this
process have absolute metallicities below 10−3 Z⊙.
We also find that the fraction of externally enriched halos increases
with time: ~90% of halos that are externally enriched have Mvir < 106 M⊙,
and that pair-instability supernovae contribute the most to the
enrichment of the intergalactic medium as a whole and are thus are the
predominant supernova type contributing to the external enrichment of
halos.
Original language | English |
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Pages (from-to) | 1-11 |
Number of pages | 11 |
Journal | Astrophysical Journal |
Volume | 909 |
Issue number | 1 |
DOIs | |
Publication status | Published - 8 Mar 2021 |
Keywords
- astro-ph.GA