Enhanced activity of massive black holes by stellar capture assisted by a self-gravitating accretion disc

Abstract

Aims.We study the probability of close encounters between stars from a nuclear cluster and a massive black hole (104; ). The gravitational field of the system is dominated by the black hole in its sphere of influence. It is further modified by the cluster mean field (a spherical term) and a gaseous disc/torus (an axially symmetric term) causing a secular evolution of stellar orbits via Kozai oscillations. Intermittent phases of high eccentricity increase the chance that stars become damaged inside the tidal radius of the central hole. Such events can produce debris and lead to recurring episodes of enhanced accretion activity.