Authors: Balsa Terzic & Alister W. Graham
Abstract: Popular models for describing the luminosity-density profiles of dynamically hot stellar systems (e.g., Jaffe, Hernquist, Dehnen) were constructed with the desire to match the deprojected form of an R1/4 light-profile. Real galaxies, however, are now known to have a range of different light-profile shapes that scale with mass. Consequently, the above models have implicit limitations, and this is illustrated here through their application to a number of real galaxy density profiles. On the other hand, the analytical density profile given by Prugniel & Simien (1997) closely matches the deprojected form of Sersic's R1/n light-profile (including deprojected exponential light-profiles). It is thus applicable for describing bulges in spiral galaxies, dwarf elliptical galaxies, and both ordinary and giant elliptical galaxies. Here we provide simple equations, in terms of elementary and special functions, for the gravitational potential and force associated with this density profile. Furthermore, to match galaxies with partially depleted cores, and better explore the supermassive black hole / galaxy connection, we have added a power-law core to this density profile and derived similar expressions for the potential and force of this hybrid profile. Expressions for the mass and velocity dispersion, assuming isotropy, are also given. These models may also prove appropriate for describing the dark matter distribution in halos formed from LCDM cosmological simulations.