Population III Star Formation In Large Cosmological Simulations I. Halo Temporal and Physical Environment

TL;DR

This paper introduces a semi-analytic model to identify potential Population III star-forming halos in cosmological simulations, revealing their environmental conditions, formation history, and coexistence with enriched stars from early universe to z~10.

Contribution

The study presents a novel, computationally efficient model to identify and analyze Population III star-forming halos across diverse environments and times in large cosmological simulations.

Findings

Population III stars coexist with enriched stars until at least z~10.

Over 40,000 candidate halos identified with formation redshifts from 30 to 10.

Population III stars form in low-density, chemically unpolluted regions at later times.

Abstract

We present a semi-analytic, computationally inexpensive model to identify halos capable of forming a Population III star in cosmological simulations across a wide range of times and environments. This allows for a much more complete and representative set of Population III star forming halos to be constructed, which will lead to Population III star formation simulations that more accurately reflect the diversity of Population III stars, both in time and halo mass. This model shows that Population III and chemically enriched stars coexist beyond the formation of the first generation of stars in a cosmological simulation until at least z~10, and likely beyond, though Population III stars form at rates that are 4-6 orders of magnitude lower than chemically enriched stars by z=10. A catalog of more than 40,000 candidate Population III forming halos were identified, with formation times temporally ranging from z=30 to z=10, and ranging in mass from 2.3x10^5 M_sun to 1.2x10^10 M_sun. At early times, the environment that Population III stars form in is very similar to that of halos hosting chemically enriched star formation. At later times Population III stars are found to form in low-density regions that are not yet chemically polluted due to a lack of previous star formation in the area. Population III star forming halos become increasingly spatially isolated from one another at later times, and are generally closer to halos hosting chemically enriched star formation than to another halo hosting Population III star formation by z~10.