  The thermal history of the intergalactic medium (IGM) after reionization is
to a large extent determined by photoheating. Here we demonstrate that
calculations of the photoheating rate which neglect radiative transfer effects
substantially underestimate the energy input during and after reionization. The
neglect of radiative transfer effects results in temperatures of the IGM which
are too low by a factor of two after HeII reionization. We briefly discuss
implications for the absorption properties of the IGM and the distribution of
baryons in shallow potential wells.
