title: Annihilating cold dark matter
abstract: Structure formation with cold dark matter (CDM) predicts halos with a central density cusp, which are observationally disfavored. If CDM particles have an annihilation cross section sigmav approximately 10(-29)(m/GeV) cm(2), then annihilations will soften the cusps. We discuss plausible scenarios for avoiding the early Universe annihilation catastrophe that could result from such a large cross section. The predicted scaling of core density with halo mass depends upon the velocity dependence of sigmav, and s-wave annihilation leads to a core density nearly independent of halo mass, which seems consistent with observations.
authors.affiliation: Department of Astronomy and Astrophysics, The University of Chicago, 5640 S. Ellis Avenue, Chicago, Illinois 60637, USA.
authors.initials: M
authors.lastname: Kaplinghat
authors.initials: L
authors.lastname: Knox
authors.initials: MS
authors.lastname: Turner