Tracing the Evolution of High Redshift Galaxies Using Stellar Abundances
  This paper presents the first results from a model for chemical evolution
that can be applied to N-body cosmological simulations and quantitatively
compared to measured stellar abundances from large astronomical surveys. This
model convolves the chemical yield sets from a range of stellar nucleosynthesis
calculations (including AGB stars, Type Ia and II supernovae, and stellar wind
models) with a user-specified stellar initial mass function (IMF) and
metallicity to calculate the time-dependent chemical evolution model for a
"simple stellar population" of uniform metallicity and formation time. These
simple stellar population models are combined with a semi-analytic model for
galaxy formation and evolution that uses merger trees from N-body cosmological
simulations to track several $\alpha$- and iron-peak elements for the stellar
and multiphase interstellar medium components of several thousand galaxies in
the early ($z \geq 6$) universe. The simulated galaxy population is then
quantitatively compared to two complementary datasets of abundances in the
Milky Way stellar halo, and is capable of reproducing many of the observed
abundance trends. The observed abundance ratio distributions are qualitatively
well matched by our model, and the observational data is best reproduced with a
Chabrier IMF, a chemically-enriched star formation efficiency of $0.2$, and a
redshift of reionization of $7$.
