Two (or three?) black holes in one galactic center

Two (or three?) black holes in one galactic center

It has long been known that galaxies can merge; thus, we should expect their central supermassive black holes to interact as well. However, our ability to study this is limited as most mergers happen in the distant universe. The exceptional nearby source CID-42 can be explained by a recent binary or triple supermassive black hole interaction, giving astronomers a rare chance to witness the repercussions of such an event.