Abstract:
Encounters between stars and stellar remnants at the centers of galaxies drive many important processes. The fact that these encounters take place near a supermassive black hole (SBH) alters the dynamics in a number of ways:
(1) The orbital motion is quasi-Keplerian so that correlations are maintained for much longer than in purely random encounters;
(2) relativity affects the motion, through mechanisms like precession of the periastron and frame dragging;
(3) the SBH spin is affected, directly by capture and indirectly by spin-orbit torques.
The interplay between these processes is just now beginning to be understood, but a key result is that relativity can be crucially important even at distances that are a substantial fraction of the SBH influence radius. I will discuss this work and its implications for stellar captures, for the evolution of SBH spins, and for the long-term evolution of galactic nuclei.