AST 98-03199 August Evrard The formation of galaxies is a complex problem central to observational cosmology. The problem involves solving for the fluid dynamic and thermodynamic behavior of a set of fluids (dark matter, baryonic gas, and stars) coupled in a highly non-linear manner over a wide dynamic range in physical scales. Numerical simulations provide a means to address this problem. The PI is modeling the parameter space associated with numerical simulations of galaxy formation in groups and clusters. He is using two independent codes: the P3MSPH code developed by the PI, and the Virgo consortium's Hydra code These both run on parallel machines. The science objectives of the project are (1) what aspects of modeled clusters are numerically robust? (2) what processes determine the relative fractions of baryons in galaxies and the intracluster medium? (3) can a single model for galaxy formation reproduce the observed optical and x-ray characteristics of groups and clusters? (4) how do galaxies trace the total mass in clustered environments? This is a phased study to (1) investigate stability to numerical parameters, (2) to calibrate response to star formation and feedback prescriptions, (3) explore dependence across a spectrum of cluster sizes, (4) explore sensitivity to the cosmological model. ***
