The distribution of violently relaxed matter in galaxies

A scenario of galaxy formation is considered in which the halo and spheroidal components were formed by collapse and violent relaxation of a heavy protogalactic mass. Before the point of maximum collapse, most stars would be formed; with the dark component consisting of collisionless objects, essentially all the galactic matter would have violently relaxed. The dark matter would then be isothermally distributed, accounting for the deduced approximate proportionality of the halo mass density to the inverse square of the radius. If the velocity dispersion of stars in the spheroid is smaller than that of the halo objects, the density of the stars would be a steeper function of the radius. Some aspects of Lynden-Bell's (1967) theory of violent relaxation which may possibly account for these features in the distribution of matter in galaxies are outlined and illustrated for a model galaxy.