MOCCA-SURVEY Database I. Intermediate mass black holes in Milky Way globular clusters and their connection to supermassive black holes

In this paper we explore the interplay between intermediate-mass black holes (IMBHs) and their nursing globular clusters (GCs), taking advantage of over 2000 Monte Carlo GC models. We find that the average density of IMBHs sphere of influence can be uniquely connected to the host GCs luminosity and half-light radius via a fundamental plane. We propose a statistical approach to systematically identify potential Galactic GCs harbouring either an IMBH or a massive subsystem comprised of stellar BHs. Our models show that the IMBH is often bound to a stellar companion or a stellar BH, which can lead to tidal disruption events or to low-frequency gravitational waves. We show that GCs orbiting close to the Galactic Centre have a larger probability to witness IMBH formation during their early evolution. These low-orbit GCs can deliver several IMBHs into the galaxy innermost regions, with potential impact on both electromagnetic and GW emission. We discuss potential connections between IMBHs and SMBHs inhabiting galactic nuclei, exploring the possibility that in some cases they share similar formation pathways.