Dark Satellites: How They Lost Their Baryons

We present a study of satellites in orbit around simulated host galaxies. The cumulative number of luminous satellites at z = 0 is similar to the observed system of satellites orbiting the Milky Way, although an analysis of the satellite mass function reveals an order of magnitude more dark satellites than luminous. Our results demonstrate that the missing satellite problem is not an intractable issue with the cold dark matter cosmology, but is rather a manifestation of baryonic processes. What separates luminous and dark subhalos is not their mass at z = 0, but the maximum mass the subhalos ever achieve. We study the effect of four mass-loss mechanisms on the subhalos: ultraviolet (UV) ionising radiation, ram pressure stripping, tidal stripping, and stellar feedback, and compare their impact on the satellites.