Local Group progenitors: Lyman Alpha bright?
  We present a novel approach of identifying the Milky Way (MW) and Andromeda
(M31) progenitors that could be visible as LAEs at z~6: we couple a snapshot
from the Constrained Local UniversE Simulations (CLUES) project, that
successfully reproduces the MW and M31 galaxies situated in their correct
environment, to a Lyman Alpha Emitter (LAE) model. Exploring intergalactic
medium (IGM) ionization states ranging from an almost neutral to a fully
ionized one, we find that including (excluding) the effects of clustered
sources the first local group progenitor appears as a LAE for a neutral
hydrogen fraction of 0.4 (0.1). This number increases to 5 progenitors each of
the MW and M31 being visible as LAEs for a completely ionized IGM; the
contribution from clustered sources is crucial in making many of the
progenitors visible in the Lyman Alpha, for all the ionization states
considered. We also put constrains on the physical properties of such
progenitors. Finally, we find that the number density of these LAEs are higher
than that of general field LAEs (observed in cosmological volumes) by about two
(one) orders of magnitude for a neutral hydrogen fraction of 10^-5 (0.4).
Detections of such high LAE number densities at z ~ 6 would be a clear
signature of an over-dense region that could evolve and resemble the local
group volume at z=0.
