The Local Cosmology from Isolated Dwarfs (LCID) Project

Evan Skillman

Minnesota

I will present an overview of the LCID project - a large Hubble Space Telescope program aimed at deriving detailed star formation and chemical enrichment histories for a sample of isolated Local Group dwarf galaxies. The details of the early star formation histories of isolated dwarf galaxies can shed light on the roles of the cosmic re-ionization and supernova feedback in galaxy formation and evolution. The radial gradients in the star formation histories provide insight into the structural evolution of dwarf galaxies. The variable star populations provide independent constraints on the strengths and distributions of the earliest star formation. Comparison of the star formation histories with various galaxy evolution models demonstrate that star formation is not directly coupled to mass assembly in dwarf galaxies. Comparing the results for isolated dwarfs with those obtained for the Milky Way and M31 satellites sheds new light on the effects of environmental mechanisms, which are expected to dominate for satellite galaxies.