Chemical Evolution in Hierarchical Models of Cosmic Structure II: The
  Formation of the Milky Way Stellar Halo and the Distribution of the Oldest
  Stars
  This paper presents theoretical star formation and chemical enrichment
histories for the stellar halo of the Milky Way based on new chemodynamical
modeling. The goal of this study is to assess the extent to which metal-poor
stars in the halo reflect the star formation conditions that occurred in halo
progenitor galaxies at high redshift, before and during the epoch of
reionization. Simple prescriptions that translate dark-matter halo mass into
baryonic gas budgets and star formation histories yield models that resemble
the observed Milky Way halo in its total stellar mass, metallicity
distribution, and the luminosity function and chemical enrichment of dwarf
satellite galaxies. These model halos in turn allow an exploration of how the
populations of interest for probing the epoch of reionization are distributed
in physical and phase space, and of how they are related to lower-redshift
populations of the same metallicity. The fraction of stars dating from before a
particular time or redshift depends strongly on radius within the galaxy,
reflecting the "inside-out" growth of cold-dark-matter halos, and on
metallicity, reflecting the general trend toward higher metallicity at later
times. These results suggest that efforts to discover stars from z > 6 - 10
should select for stars with [Fe/H] <~ -3 and favor stars on more tightly bound
orbits in the stellar halo, where the majority are from z > 10 and 15 - 40% are
from z > 15. The oldest, most metal-poor stars - those most likely to reveal
the chemical abundances of the first stars - are most common in the very center
of the Galaxy's halo: they are in the bulge, but not of the bulge. These models
have several implications for the larger project of constraining the properties
of the first stars and galaxies using data from the local Universe.
