Self-consistent two-component models of elliptical galaxies

Spherical self-consistent elliptical galaxy models, embedded in a dark matter halo, are constructed. Two different stellar distributions are considered: The King law, and another one reproducing the Rl/4 luminosity law; the stellar mass-to-light ratio is constant. The concentration and the amount of the stellar and dark matter distributions are determined by five parameters; two characteristic radii determine the radial trend of the anisotropy for the stellar and dark halo velocity dispersion tensors. We introduce the multicomponent decomposition of dynamical models of galaxies, and a theorem concerning their consistency; then, we determine the region of the parameter space where the models are self-consistently generated. For some models lying in this region the stellar velocity dispersion profiles are described in detail, pointing out the effects of the anisotropy and of the dark matter. We also show the errors induced by these effects on the results of the most common methods of elliptical galaxies' mass estimation. We finally discuss the reduction produced by the so-called fundamental plane in the number of independent parameters, and their role in the energetics of hot gas flows in ellipticals.