Unprecedented Black Hole Merger Puts Physics Models to the Test
Scientists have detected the most massive black hole merger ever observed through gravitational waves, resulting in a final black hole 225 times the mass of our Sun. The event, known as GW231123, was detected on November 23, 2023, by the esteemed LIGO-Virgo-KAGRA collaboration.
The announcement was made at the International Conference on General Relativity and Gravitation in Glasgow on July 14, 2025. The merger involved two black holes of approximately 100 and 140 solar masses, both spinning at near-maximum speeds as allowed by Einstein’s theory of relativity.
“This is the most massive black hole binary we’ve observed through gravitational waves, and it presents a real challenge to our understanding of black hole formation,” says Professor Mark Hannam of Cardiff University.
The discovery challenges current stellar evolution models. Black holes of this magnitude are considered “forbidden” by standard theories, suggesting they likely formed through earlier mergers of smaller black holes.
Source: Caltech