The Case for a Universal Density Profile in Clusters of Galaxies

Abstract

We study the radial profiles of 15 cluster-size halos from high resolution adiabatic SPH simulations. We conclude that the dark matter density of relaxed clusters can be fitted by a NFW profile, while recent mergers are closer to Moore et al. (1999) formula. The gas density can also be described to a good approximation as a simple, universal profile, when it is properly scaled. Moreover, we find that gas temperature has a radial dependence which can be fitted by a scale invariant form similar to the expression recently found in eulerian gasdynamical simulations. The mass distribution in clusters can be explained using the spherical collapse model when non-radial motions are taken into account. Indeed, we find that the amount of angular momentum determines the shape of the density profile near the center.