The Detectability of Lyman Alpha Emission from Galaxies during the Epoch
  of Reionization
  We study the visibility of the Lyman Alpha (Lya) emission line during the
Epoch of Reionization (EoR). Combining galactic outflow models with large-scale
semi-numeric simulations of reionization, we quantify the probability
distribution function (PDF) of the fraction of Lya photons transmitted through
the intergalactic medium (IGM), T_IGM. Our study focusses on galaxies
populating dark matter halos with masses of M_halo=1e10 M_sun at z=8.6, which
is inspired by the recent reported discovery of a galaxy at z=8.6 with strong
Lya line emission. For reasonable model assumptions, we find that winds cause
T_IGM>10% [50%], for the majority of galaxies, even when the Universe is ~80%
[60%] neutral by volume. Thus, the observed strong Lya emission from the
reported z=8.6 galaxy is consistent with a highly neutral IGM. We also
investigate the implications of the recent tentative evidence for a observed
decrease in the `LAE fraction' among drop-out galaxies between z=6 and z=7. If
confirmed, we show that a rapid evolution in x_HI will be required to explain
this observation via the effects of reionization.
