First stars in Damped Lyman Alpha systems
  In order to characterize Damped Lyman Alpha systems (DLAs) potentially
hosting first stars, we present a novel approach to investigate DLAs in the
context of Milky Way (MW) formation, along with their connection with the most
metal-poor stars and local dwarf spheroidal (dSph) galaxies. The merger tree
method previously developed is extended to include inhomogeneous reionization
and metal mixing, and it is validated by matching both the Metallicity
Distribution Function of Galactic halo stars and the Fe-Luminosity relation of
dSph galaxies. The model explains the observed NHI-Fe relation of DLAs along
with the chemical abundances of [Fe/H] < -2 systems. In this picture, the
recently discovered z_abs ~ 2.34 C-enhanced DLA (Cooke et al. 2011a), pertains
to a new class of absorbers hosting first stars along with second-generation
long-living low-mass stars. These "PopIII DLAs" are the descendants of
H2-cooling minihalos with Mh ~ 10^7 Msun, that virialize at z > 8 in neutral,
primordial regions of the MW environment and passively evolve after a short
initial period of star formation. The gas in these systems is warm Tg \sim
(40-1000) K, and strongly C-enriched by long-living, extremely metal-poor stars
of total mass M* \sim 10^{2-4} Msun.
