REVISITING THE FIRST GALAXIES: THE EPOCH OF POPULATION III STARS

摘要

We investigate the transition from primordial Population III (Pop III) star formation to normal Pop?II star formation in the first galaxies using new cosmological hydrodynamic simulations. We find that while the first stars seed their host galaxies with metals, they cannot sustain significant outflows to enrich the intergalactic medium, even assuming a top-heavy initial mass function. This means that Pop?III star formation could potentially continue until z ≈ 6 in different unenriched regions of the universe, before being ultimately shut off by cosmic reionization. Within an individual galaxy, the metal production and stellar feedback from Pop?II stars overtake Pop?III stars in 20-200?Myr, depending on galaxy mass.