How the Population III Initial Mass Function Governs the Properties of the First Galaxies

The properties of Population III (Pop III) stars impact many aspects of primeval structure formation such as the onset of cosmological reionization and early chemical enrichment. However, in spite of over twenty years of numerical simulations and attempts to constrain the Pop III initial mass function (IMF) by stellar archaelogy, little is known of the masses of the first stars for certain. Here, we model the effect of Pop III IMF on the properties of primeval galaxies with a suite of high-resolution radiation-hydrodynamical simulations with ENZO. We find that a top-heavy Pop III IMF results in earlier star formation but dimmer galaxies than a more conventional Salpeter-type IMF because explosions of massive Pop III stars produce more turbulence that suppresses high-mass second-generation star formation. Our models suggest that the Pop III IMF could therefore be inferred from detections of primordial galaxies, which will be principal targets of the James Webb Space Telescope and extremely large telecopes on the ground in the coming decade.