Limits RegistryPUBLIC RECORD
Limits RegistryGW190521, detected by LIGO and Virgo on May 21, 2019, resulted from the merger of two black holes of roughly 85 and 66 solar masses, producing a remnant of about 142 solar masses — the most massive black hole merger observed via gravitational waves, and the first confirmed direct detection of an intermediate-mass black hole (a class between stellar-mass and supermassive black holes). One of the progenitor masses also falls inside the theoretical 'pair-instability supernova gap' where stars are not expected to leave black holes behind, making the event doubly notable.
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GW190521, detected by LIGO and Virgo on May 21, 2019, resulted from the merger of two black holes of roughly 85 and 66 solar masses, producing a remnant of about 142 solar masses — the most massive black hole merger observed via gravitational waves, and the first confirmed direct detection of an intermediate-mass black hole (a class between stellar-mass and supermassive black holes). One of the progenitor masses also falls inside the theoretical 'pair-instability supernova gap' where stars are not expected to leave black holes behind, making the event doubly notable.
The greatest final remnant mass produced by any black hole merger event confirmed through gravitational-wave detection.
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Limits Registry. LR-MOST-MASSIVE-BLACK-HOLE-MERGER. Most massive black hole merger detected by gravitational waves. 2026.