Astronomy - Colloquia

Fueled by continuing advances in numerical methods and computational
capabilities, the future of galaxy formation theory is going to be
driven by numerical simulations. Yet computational galaxy formation is
extremely challenging, owing to the multitude of important physical
processes and the wide range of scales over which they operate. Much
of the galaxy formation simulation work to date has relied on simple,
and often ad-hoc, subgrid models for star formation and feedback. In
this talk I will describe my recent efforts to improve this situation
by including more realistic and physics-driven treatments of some of
the relevant processes. As one example, I will discuss cosmological
adaptive mesh refinement simulations in which star formation is
regulated by the local abundance of molecular hydrogen. These
simulations reproduce much of the observational phenomenology of star
formation rates as a function of atomic and molecular gas content and
metallicity. At the same time this new piece of physics leads to a
suppression of the stellar content of low mass dark matter
halos, thereby helping to explain the vexing dwarf galaxy problem.