Were progenitors of local L* galaxies Lyman-alpha emitters at high
  redshift?
  The Lya emission has been observed from galaxies over a redshift span z ~ 0 -
8.6. However, the evolution of high-redshift Lya emitters (LAEs), and the link
between these populations and local galaxies, remain poorly understood. Here,
we investigate the Lya properties of progenitors of a local L* galaxy by
combining cosmological hydrodynamic simulations with three-dimensional
radiative transfer calculations using the new ART^2 code. We find that the main
progenitor (the most massive one) of a Milky Way-like galaxy has a number of
Lya properties close to those of observed LAEs at z ~ 2 - 6, but most of the
fainter ones appear to fall below the detection limits of current surveys. The
Lya photon escape fraction depends sensitively on a number of physical
properties of the galaxy, such as mass, star formation rate, and metallicity,
as well as galaxy morphology and orientation. Moreover, we find that
high-redshift LAEs show blue-shifted Lya line profiles characteristic of gas
inflow, and that the Lya emission by excitation cooling increases with
redshift, and becomes dominant at z > 6. Our results suggest that some observed
LAEs at z ~ 2-6 with luminosity of L_Lya ~ 10^{42-43} ergs/s may be similar to
the main progenitor of the Milky Way at high redshift, and that they may evolve
into present-day L* galaxies.
