COLLAPSE AND VIOLENT RELAXATION OF A SPHERICAL PROTO-GALAXY

The collapse and violent relaxation of a spherical protogalaxy is investigated. The method devised by the authors and described in an accompanying paper, in which the Vlasov and Poisson equations are solved in a three-dimensional phase space, is used. Our conclusions are that the steady state obtained depends on the initial conditions and can be made to agree with observations of the density profile in E galaxies without assuming matter infall (Gott's model) or star formation during the collapse (Larson's model). The steady state is not in a complete or local thermodynamic equilibrium. We find that the moment approach or the hydrodynamic approximation neglect some essential features of the collapse. We show that the relaxation proceeds from the high energy stars towards the low energy ones and from long spatial wavelengths towards short ones. © 1979 Royal Astronomical Society.