Lyman-alpha emitters gone missing: evidence for late reionization?
  We combine high resolution hydrodynamical simulations with an intermediate
resolution, dark matter only simulation and an analytical model for the growth
of ionized regions to estimate the large scale distribution and redshift
evolution of the visibility of Lyman-alpha emission in 6<=z<=8 galaxies. The
inhomogeneous distribution of neutral hydrogen during the reionization process
results in significant fluctuations in the Lyman-alpha transmissivity on large
scales. The transmissivity depends not only on the ionized fraction of the
intergalactic medium by volume and the amplitude of the local ionizing
background, but is also rather sensitive to the evolution of the relative
velocity shift of the Lyman-alpha emission line due to resonant scattering. We
reproduce a decline in the space density of Lyman-alpha emitting galaxies as
rapid as observed with a rather rapidly evolving neutral fraction between
z=6-8, and a typical Lyman-alpha line velocity offset of 100 km/s redward of
systemic at z=6 which decreases toward higher redshift. The new (02/2015)
Planck results indicate such a recent end to reionization is no longer
disfavoured by constraints from the cosmic microwave background.
