Simulating the effect of photoheating feedback during reionization
  We present self-consistent radiation hydrodynamic simulations of hydrogen
reionization performed with Arepo-RT complemented by a state-of-the-art galaxy
formation model. We examine how photoheating feedback, due to reionization,
shapes the galaxies properties. Our fiducial model completes reionization by
$z\approx6$ and matches observations of the Ly$\alpha$ forest, the CMB electron
scattering optical depth, the high-redshift UV luminosity function, and stellar
mass function. Contrary to previous works, photoheating suppresses star
formation rates by more than $50\%$ only in halos less massive than
$\sim10^{8.4}\ M_\odot$ ($\sim10^{8.8}\ M_\odot$) at $z=6$ $(z=5)$, suggesting
inefficient photoheating feedback from photons within galaxies. The use of a
uniform UV background that heats up the gas at $z\approx10.7$ generates an
earlier onset of suppression of star formation compared to our fiducial model.
This discrepancy can be mitigated by adopting a UV background model with a more
realistic reionization history. In the absence of stellar feedback,
photoheating alone is only able to quench halos less massive than $\sim10^9\
M_\odot$ at $z\gtrsim5$, implying that photoheating feedback is sub-dominant in
regulating star formation. In addition, stellar feedback, implemented as a
non-local galactic wind scheme in the simulations, weakens the strength of
photoheating feedback by reducing the amount of stellar sources. Most
importantly, photoheating does not leave observable imprints in the UV
luminosity function, stellar mass function, or the cosmic star formation rate
density. The feasibility of using these observables to detect imprints of
reionization therefore requires further investigation.
