Resolving the Formation of Protogalaxies. III. Feedback from the First Stars

TL;DR

This paper uses advanced simulations to study how the first stars influence early dwarf galaxy formation, revealing the effects of stellar feedback, supernovae, and metal enrichment on gas dynamics and galaxy evolution.

Contribution

It provides a detailed, self-consistent simulation of Population III star feedback, supernova explosions, and metal enrichment in early dwarf galaxy formation.

Findings

Stellar feedback reduces baryon content in halos by half.

Supernovae increase gaseous spin parameters significantly.

Metallicity in halos reaches about 10^{-3} solar, with 40% in the IGM.

Abstract

The first stars form in dark matter halos of masses ~10^6 M_sun as suggested by an increasing number of numerical simulations. Radiation feedback from these stars expels most of the gas from their shallow potential well of their surrounding dark matter halos. We use cosmological adaptive mesh refinement simulations that include self-consistent Population III star formation and feedback to examine the properties of assembling early dwarf galaxies. Accurate radiative transport is modeled with adaptive ray tracing. We include supernova explosions and follow the metal enrichment of the intergalactic medium. The calculations focus on the formation of several dwarf galaxies and their progenitors. In these halos, baryon fractions in 10^8 solar mass halos decrease by a factor of 2 with stellar feedback and by a factor of 3 with supernova explosions. We find that radiation feedback and supernova explosions increase gaseous spin parameters up to a factor of 4 and vary with time. Stellar feedback, supernova explosions, and H_2 cooling create a complex, multi-phase interstellar medium whose densities and temperatures can span up to 6 orders of magnitude at a given radius. The pair-instability supernovae of Population III stars alone enrich the halos with virial temperatures of 10^4 K to approximately 10^{-3} of solar metallicity. We find that 40% of the heavy elements resides in the intergalactic medium (IGM) at the end of our calculations. The highest metallicity gas exists in supernova remnants and very dilute regions of the IGM.