Institute for Advanced Study Astrophysics Seminar

ABSTRACT: The LCDM paradigm predicts that the Milky Way dark halo has nearly 10% of its mass in the form of thousands of sub-halos, far more than can be accounted for with the known dwarf galaxies. Globular clusters dissolving in the tidal field of the galaxy create long, thin stellar stream. Sub-halos that orbit through a stream will create a density gap in the stream. The visibility of the gap depends on the stream dynamics and the size of the sub-halo. Observers have noted that star streams have significant density variations along their length. The degree to which the observed stream density variations may be quantitatively consistent with the presence of a rich dark matter sub-halo population is considered.