Dissipationless galaxy formation and the r1/4 law

Abstract

Results of collision-free N-body simulations of the collapse phase of galaxy formation are presented. A variety of irregular initial conditions produce density distributions that are in very good agreement with the r1/4 law, provided that the collapse factor is large. This agreement holds for a region between radii containing 10 and 99 per cent of the total mass in the r1/4 model and corresponds to a range in surface brightness of 12 mag. The central densities in the equilibrium configurations are up to a factor 1000 larger than the initial densities. The final models have a strongly anisotropic velocity distribution in their envelopes.