MOCCA code for star cluster simulations – IV. A new scenario for intermediate mass black hole formation in globular clusters

Abstract

We discuss a new scenario for the formation of intermediate mass black holes\nin dense star clusters. In this scenario, intermediate mass black holes are\nformed as a result of dynamical interactions of hard binaries containing a\nstellar mass black hole, with other stars and binaries. We discuss the\nnecessary conditions to initiate the process of intermediate mass black hole\nformation and the influence of an intermediate mass black hole on the host\nglobal globular cluster properties. We discuss two scenarios for intermediate\nmass black hole formation. The SLOW and FAST scenarios. They occur later or\nearlier in the cluster evolution and require smaller or extremely large central\ndensities, respectively. In our simulations, the formation of intermediate mass\nblack holes is highly stochastic. In general, higher formation probabilities\nfollow from larger cluster concentrations (i.e. central densities). We further\ndiscuss possible observational signatures of the presence of intermediate mass\nblack holes in globular clusters that follow from our simulations. These\ninclude the spatial and kinematic structure of the host cluster, possible\nradio, X-ray and gravitational wave emissions due to dynamical collisions or\nmass-transfer and the creation of hypervelocity main sequence escapers during\nstrong dynamical interactions between binaries and an intermediate mass black\nhole. All simulations discussed in this paper were performed with the MOCCA\nMonte Carlo code. MOCCA accurately follows most of the important physical\nprocesses that occur during the dynamical evolution of star clusters but, as\nwith other dynamical codes, it approximates the dissipative processes connected\nwith stellar collisions and binary mergers.\n