On the coexistence of stellar-mass and intermediate-mass black holes in globular clusters

Abstract

In this paper, we address the question: What is the probability of\nstellar-mass black hole (BH) binaries co-existing in a globular cluster with an\nintermediate-mass black hole (IMBH)? Our results suggest that the detection of\none or more BH binaries can strongly constrain the presence of an IMBH in most\nGalactic globular clusters. More specifically, the detection of one or more BH\nbinaries could strongly indicate against the presence of an IMBH more massive\nthan $\\gtrsim 10^3$ M$_{\\rm \\odot}$ in roughly 80\\% of the clusters in our\nsample. To illustrate this, we use a combination of N-body simulations and\nanalytic methods to weigh the rate of formation of BH binaries against their\nejection and/or disruption rate via strong gravitational interactions with the\ncentral (most) massive BH.\n The eventual fate of a sub-population of stellar-mass BHs (with or without\nbinary companions) is for all BHs to be ejected from the cluster by the central\nIMBH, leaving only the most massive stellar-mass BH behind to form a close\nbinary with the IMBH. During each phase of evolution, we discuss the rate of\ninspiral of the central BH-BH pair as a function of both the properties of the\nbinary and its host cluster.\n