Scientists have reported detecting gravitational waves from 10 black hole mergers to date, but they are still trying to explain the origins of those mergers. The largest merger detected so far seems to have defied previous models because it has a higher spin and mass than the range thought possible.
In a new paper published in Physical Review Letters published on November 1, 2019, the researchers suggest that such large mergers could happen just outside supermassive black holes at the center of active galactic nuclei. Gas, stars, dust and black holes become caught in a region surrounding supermassive black holes known as the accretion disk. The researchers suggest that as black holes circle around in the accretion disk, they eventually collide and merge to form a bigger black hole, which continues to devour smaller black holes, becoming increasingly large in what O’Shaughnessy calls “Pac-Man-like” behavior.