Cosmic Reionization On Computers: The Faint End of the Galaxy Luminosity
  Function
  Using numerical cosmological simulations completed under the "Cosmic
Reionization On Computers" (CROC) project, I explore theoretical predictions
for the faint end of the galaxy UV luminosity functions at $z\geq 6$. A
commonly used Schechter function approximation with the magnitude cut at
$M_{\rm CUT}\sim-13$ provides a reasonable fit to the actual luminosity
function of simulated galaxies. When the Schechter functional form is forced on
the luminosity functions from the simulations, the magnitude cut $M_{\rm CUT}$
is found to vary between $-12$ and $-14$ with a mild redshift dependence. An
analytical model of reionization from Madau, Haardt & Rees (1997), as used by
Robertson et al. (2015), provides a good description of the simulated results,
but only if the redshift dependence of the effective escape fraction (induced
by physical processes not captured by the Madau, Haardt & Rees model) is
accounted for.
