Low-mass galaxy formation and the ionizing photon budget during
  reionization
  We use high-resolution simulations of cosmological volumes to model galaxy
formation at high-redshift, with the goal of studying the photon budget for
reionization. We demonstrate that galaxy formation models that include a
strong, thermally coupled supernovae scheme reproduce current observations of
star formation rates and specific star formation rates, both during and after
the reionization era. These models produce enough UV photons to sustain
reionization at z<8 (z<6) through a significant population of faint,
unobserved, galaxies for an assumed escape fraction of 20% (5%). This predicted
population is consistent with extrapolation of the faint end of observed UV
luminosity functions. We find that heating from a global UV/X-ray background
after reionization causes a dip in the total global star formation rate density
in galaxies below the current observational threshold. Finally, while the
currently observed specific star formation rates are incapable of
differentiating between supernovae feedback models, sufficiently deep
observations will be able to use this diagnostic in the future to investigate
galaxy formation at high redshift.
