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Physics and Astronomy

Physics & Astronomy Colloquium

3:30 PM, Friday, January 18, 2013
Room 155, Chem-Phys Building

Dr. Susan Gardner
Department of Physics and Astronomy
University of Kentucky

Discovery of a north-south asymmetry in the distribution of local stars and its implications

Studies which would try to fix the local dark matter density through observations of the nearby stars invariably assume that the stars are in gravitational equilibrium. In recent years, however, it has become clear that the Milky Way displays many transient phenomena; it is a much more violent place than earlier thought. I will show how observations of the local solar neighborhood from the Sloan Digitial Sky Survey can probe the vertical equilibrium of the Galactic disk, by testing the symmetries present in the stars' distribution. Our analysis reveals a failure of north-south symmetry with respect to the galactic plane and thus that vertical equilibrium is wanting. I will consider our result in light of other observational studies, suggest further observational tests, and finally offer a perspective on its implications for dark-matter direct detection experiments.

Refreshments will be served in CP 177 at 3:15 PM