The Effects of Radiative Feedback and Supernova Induced Turbulence on Early Galaxies

TL;DR

This study demonstrates that including radiative transfer and turbulent mixing in cosmological simulations significantly impacts early galaxy formation, reducing Pop III star formation and altering galaxy morphology.

Contribution

It introduces a comparative simulation approach highlighting the importance of radiative transfer and turbulent mixing in modeling primordial galaxies.

Findings

Radiative transfer reduces Pop III star formation density by about 4 times.

Over 90% of Pop III stars are in unresolved pristine regions.

Radiative transfer leads to compact high-redshift galaxies with isolated low-mass satellites.

Abstract

The recently launched James Webb Space Telescope promises unparalleled advances in our understanding of the first stars and galaxies, but realizing this potential requires cosmological simulations that capture the key physical processes that affected these objects. Here we show that radiative transfer and subgrid turbulent mixing are two such processes. By comparing simulations with and without radiative transfer but with exactly the same physical parameters and subgrid turbulent mixing model, we show that tracking radiative transfer suppresses the Population III (Pop III) star formation density by a factor of approximately 4. In both simulations, $\gtrsim 90\%$ of Pop III stars are found in the unresolved pristine regions tracked by our subgrid model, which does a better job at modeling the regions surrounding proto-galaxy cores where metals from supernovae take tens of Myrs to mix thoroughly. At the same time, radiative transfer suppresses Pop III star formation, via the development of ionized bubbles that slows gas accretion in these regions, and it results in compact high-redshift galaxies that are surrounded by isolated low mass satellites. Thus turbulent mixing and radiative transfer are both essential processes that must be included to accurately model the morphology, composition, and growth of primordial galaxies.