Three supermassive black holes have been spotted merging into one
Astronomers have found a system of three supermassive black holes, all actively feeding, that appear to be combining into a single system – a rare event that will help elucidate the physics of complex mergers
Space
Astronomers have found a system of three supermassive black holes, all actively feeding, that appear to be combining into a single system – a rare event that will help elucidate the physics of complex mergers
By Alex Wilkins
31 December 2025
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Supermassive black holes occasionally devour or merge with other black holes
MARK GARLICK/SCIENCE PHOTO LIBRARY
Three galaxies with supermassive black holes at their centres appear to be in the process of merging into a single, giant galaxy, a process that astronomers have rarely seen.
To grow to such enormous sizes, astronomers think supermassive black holes must occasionally devour or merge with other massive black holes during collisions between galaxies. This process is difficult to spot, both because these mergers are short-lived compared with the lifetime of the black hole and because the black holes can only be easily seen if they are giving off light from actively feeding on material, which is also rare. As a result, astronomers have only caught around 150 pairs of galactic black holes in the act of merging.
