Observational Signatures of Lyman Alpha Emission from Early Galaxy
  Formation
  The next generation of telescopes aim to directly observe the first
generation of galaxies that initiated the reionization process in our Universe.
The Lyman Alpha (Lya) emission line is robustly predicted to be the most
prominent intrinsic spectral feature of these galaxies, making it an ideal
target to search for and study high-redshift galaxies. I briefly discuss why
Lya emitting galaxies (LAEs) provide a good probe of the intergalactic medium
(IGM) during the Epoch of Reionization (EoR). I argue that if we wish to fully
exploit LAEs as a probe of the EoR, it is important to understand what drives
their observed redshift evolution after reionization is completed. One
important uncertainty in interpreting existing LAE observations relates to the
impact of the ionized IGM on Lya photons emitted by galaxies, which is strongly
connected to the effects of scattering through HI in galactic outflows.
Scattering through galactic outflows can also modify the Lya spectral line
shape such that > 5% of the emitted Lya radiation is transmitted directly to
the observer, even through a fully neutral IGM. Finally, I discuss what is
required --observationally and theoretically-- to resolve the uncertainties
that affect existing interpretations of data on LAEs.
