Monster Black Hole Merger Is Most Massive Ever Seen

image via New Scientist

July 15, 2025, 5:00 PM

• •Physicists detected the most massive merger of black holes yet, challenging existing physics models.
• •The event, named GW231123, involved black holes of unusually high mass and spin, potentially offering clues about black hole growth in the universe.
• •This discovery was made possible by the Laser Interferometer Gravitational-Wave Observatory (LIGO), and its future is threatened by proposed funding cuts.
• •The research suggests these intermediate-mass black holes may play a role in galaxy evolution through hierarchical mergers.

Scientists have observed the largest black hole merger ever recorded, a collision between two massive black holes, which occurred in November 2023 and was detected by the LIGO observatory. The event, named GW231123, involved black holes with masses significantly higher than expected, challenging current models of black hole formation and growth. These black holes also exhibited extremely rapid spin, close to the theoretical maximum, providing new insights into their properties and evolution. The discovery underscores the importance of gravitational wave detection and the potential impact of funding cuts on future research.

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