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 .