The Structure of Cold Dark Matter Halos

Abstract. We investigate the internal structure of cold dark matter halos using high resolution N-body simulations. As the mass and force resolution are increased, halo density profiles become steeper, asymptoting to a slope of ∼ −4/3 in the central regions and may not have converged to a unique result. At our highest resolution we have nearly 3 million particles within the virial radius, R200, and force softening that is ∼ 0.2%R200. This resolution has also allowed us to resolve a large part of the overmerging problem- we find over 1000 surviving dark halos orbiting within a single cluster potential. These data have given us unprecedented insights into the dynamics and structure of “halos within halos”, allowing us for the first time, to compare the distribution of dark matter with observations of galaxies in clusters. 1.