Influence of Black Holes on Stellar Orbits

Abstract

We review the current state of dynamical modeling for galaxies in terms of being able to measure both the central black hole mass and stellar orbital structure. Both of these must be known adequately to measure either property. The current set of dynamical models do provide accurate estimates of the black hole mass and the stellar orbital distribution. Generally, these models are able to measure the black hole mass to about 20%--30% accuracy given present observations, and the stellar orbital structure to about 20% accuracy in the radial to tangential dispersions. The stellar orbital structure of the stars near the galaxy center show strong tangential velocity anisotropy for most galaxies studied. Theoretical models that best match this trend are black hole binary/merger models. There is also a strong correlation between black hole mass and the contribution of radial motion at large radii. This correlation may be an important aspect of galaxy evolution.

15 pages,to appear in "Carnegie Observatories Astrophysics Series, Vol. 1: Coevolution of Black Holes and Galaxies," ed. L. C. Ho (Pasadena: Carnegie Observatories, http://www.ociw.edu/ociw/symposia/series/symposium1/proceedings.html)