Mark Dijkstra, Andrei Mesinger, Stuart Wyithe
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.
View original:
http://arxiv.org/abs/1101.5160
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