13 September 2007

Speaker: Michael Blanton (New York University)

Title: What Low Luminosity Galaxies Tell Us About Cosmology

Abstract: The major features of the cold dark matter cosmological model are now well-established, with the age of the Universe and the contributions of dark matter and dark energy, all well known based on observations of the Universe on large scales. This picture also makes a series of predictions about what happens in the Universe on much smaller scales, for example the scales of dwarf galaxies. I will discuss a method of testing cold dark matter theory using the dynamics and number density of isolated dwarf galaxies (galaxies in halos circular velocities around 50 km/s). Such isolated dwarf galaxies also present an interesting laboratory for studying galaxy formation: they are not strongly interacting, they probably have quiescent merger histories, and most of their gas has not yet been formed into stars. I will present preliminary results on the formation history of such galaxies and how they differ from dwarf galaxies that have interacted with a larger neighbor.