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We study the probability of close encounters between stars from a nuclearcluster and a massive black hole. The gravitational field of the system isdominated by the black hole in its sphere of influence. It is further modifiedby the cluster mean field (a spherical term) and a gaseous disc/torus (anaxially symmetric term) causing a secular evolution of stellar orbits via Kozaioscillations. Intermittent phases of large eccentricity increase the chancethat stars become damaged inside the tidal radius of the central hole. Suchevents can produce debris and lead to recurring episodes of enhanced accretionactivity. We introduce an effective loss cone and associate it with tidaldisruptions during the high-eccentricity phases of the Kozai cycle. Bynumerical integration of the trajectories forming the boundary of the loss conewe determine its shape and volume. We also include the effect of relativisticadvance of pericentre. The potential of the disc has the efffect of enlargingthe loss cone and, therefore, the predicted number of tidally disrupted starsshould grow by factor of ~10^2. On the other hand, the effect of the clustermean potential together with the relativistic pericentre advance act againstthe eccentricity oscillations. In the end we expect the tidal disruption eventsto be approximately ten times more frequent in comparison with the model inwhich the three effects -- the cluster mean field, the relativistic pericentreadvance, and the Kozai mechanism -- are all ignored. The competition ofdifferent influences suppresses the predicted star disruption rate as the blackhole mass increases. Hence, the process under consideration is more importantfor intermediate-mass black holes, M_bh~10^4M_s.

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