Starting Reionization with the First Stars and Galaxies

Abstract

The first stars are thought to be extremely luminous and reside in dark matter halos with masses of approximately a million solar masses. I will present results from radiation hydrodynamics simulations that follow the formation of tens of metal-free stars and their impact on high-redshift galaxy formation and reionization. HII regions created by the first stars are a few kiloparsecs in radius, which then overlap with each other and constitute a volume filling fraction of about a quarter at redshift 15. Our simulations also include pair-instability supernovae and the ensuing chemical enrichment of the IGM and subsequent star formation. We find that the first galaxies are enriched up to 1/1000th of solar metallicity, which is sufficient to transition to lower-mass star formation. The escape fraction in such galaxies always exceeds 0.25 and can reach up to 0.8 in some cases.