How the First Stars Regulated Star Formation. II. Enrichment by Nearby Supernovae

TL;DR

This study uses high-resolution simulations to explore how nearby supernovae enriched primordial halos with metals, influencing the formation of Population II stars and the early evolution of galaxies.

Contribution

It provides detailed small-scale simulations showing the impact of supernova ejecta on primordial halos, highlighting the importance of partial evaporation for subsequent star formation.

Findings

Supernova ejecta mix violently with halo gas, forming dense, enriched clumps.

Partial evaporation by the progenitor star affects metal mixing and star formation outcomes.

Both Pop II and III stars can form after supernova impact depending on gas stripping.

Abstract

Metals from Population III (Pop III) supernovae led to the formation of less massive Pop II stars in the early universe, altering the course of evolution of primeval galaxies and cosmological reionization. There are a variety of scenarios in which heavy elements from the first supernovae were taken up into second-generation stars, but cosmological simulations only model them on the largest scales. We present small-scale, high-resolution simulations of the chemical enrichment of a primordial halo by a nearby supernova after partial evaporation by the progenitor star. We find that ejecta from the explosion crash into and mix violently with ablative flows driven off the halo by the star, creating dense, enriched clumps capable of collapsing into Pop II stars. Metals may mix less efficiently with the partially exposed core of the halo, so it might form either Pop III or Pop II stars. Both Pop II and III stars may thus form after the collision if the ejecta do not strip all the gas from the halo. The partial evaporation of the halo prior to the explosion is crucial to its later enrichment by the supernova.