Dynamics of dark-matter cusps

Formation and disruption of dark-matter cusps axe reviewed. Accumulation of baryons at the center of a halo can displace the dark matter, converting singular density cusps into low-density cores. The displaced mass can be of order similar to 10M. with M. the mass of the infalling population. If M. is identified with the masses of the black holes currently observed at the centers of bright galaxies, predicted core radii are similar to a few X 10(2) pc. Other mechanisms, such as early mass outflow, may explain the large dark-matter cores in dwarf and low-surface-brightness galaxies. Predictions of dark matter annihilation radiation from the center of the Milky Way galaxy are shown to be strongly dependent on the galaxy's merger history.