ANALYTICAL DYNAMICAL MODELS FOR DOUBLE POWER-LAW GALACTIC NUCLEI

Motivated by the finding that the observed surface brightness profiles of many galactic nuclei are fitted well by double power laws, we expl ore a range of spherical self-consistent dynamical models with this li ght profile. We, find that the corresponding deprojected volume densit y profile, phase-space density and line-of-sight velocity distribution of these models are fitted well by simple analytic approximations. We illustrate the application of these models by fitting a sample of app roximately 25 galactic nuclei observed by the Hubble Space Telescope ( HST). Without a central black hole and strong anisotropy the models ge nerally predict a negligibly small kurtosis parameter k(4). These mode ls with a simple distribution function are suited to seed N-body simul ations of galactic nuclei with realistic density profiles for studying the evolution of these systems.