  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.
