The connection between stellar and nuclear clusters: Can an IMBH be sitting at the heart of the Milky Way?

Abstract

AbstractA vast number of observed galactic nuclei are known to harbour a central supermassive black hole (SMBH). In their early lifetime, these systems might have witnessed the strong interaction between the SMBH and massive star clusters formed in the inner galactic regions. Due to the strong tidal field exerted from the SMBH, clusters are likely to undergo tidal disruption, releasing their stars all around the SMBH, and possibly driving the formation of a nuclear cluster (NC). This mechanism can contribute to populate galactic nuclei with intermediate-mass black holes (IMBH). Interactions with the central SMBH can lead to the formation of tight massive BH binaries (MBBH) that undergo coalescence via gravitational waves (GW) emission. We discuss this mechanism in the context of the Milky Way centre, exploring the possibility that SgrA*, the Galactic SMBH, has an IMBH companion.