ar X iv : a st ro - p h / 04 03 14 0 v 1 5 M ar 2 00 4 Dynamics of Intermediate Mass Black Holes in Star Clusters

We have followed the evolution of multi-mass star clusters containing massive central black holes by N-body simulations on the GRAPE6 computers of Tokyo University. We find a strong cluster expansion and significant structural changes of the clusters. Clusters with IMBHs have power-law density profiles ρ ∼ r −α with slopes α = 1.55 inside the influence sphere of the central black hole. This leads to a constant density profile of bright stars in projection, which rules out the presence of intermediate mass black holes in core collapse clusters. If the star clusters are surrounded by a tidal field, a central IMBH speeds up the destruction of the cluster until a remnant of a few hundred stars remains, which stays bound to the IMBH for a long time. We also discuss the efficiency of different detection mechanisms for finding IMBHs in star clusters.