Omega Centauri is a massive star cluster with nearly ten million stars located in the constellation Centaurus. For a long time, researchers have noticed that the velocities of stars moving near the centre of Omega Centauri were higher than expected. But it wasn't clear whether this was caused by an "intermediate mass" black hole (IMBH), weighing a hundred thousand times the mass of the Sun, or a cluster of "stellar mass" black holes, each weighing just a few times the mass of the Sun.
