Scaling evolution of universal dark matter halo density profiles

Dark matter halos show a universal density profile with a scaling such that less massive systems are typically denser. This mass-density relation is w ell described by a proportionality between the characteristic density of ha los and the mean cosmic density at halo formation time. It has recently bee n shown that this proportionality could be the result of the following simp le evolutionary picture. Halos form in major mergers with essentially the s ame, cosmogony-dependent, dimensionless profile and then grow inside out as a consequence of accretion. Here we verify the consistency of this picture and show that it predicts the correct zero point of the mass-density relat ion.