Fatma Zehra Solmaz
14 July 2025•Update: 15 July 2025
ISTANBUL
Scientists have detected the most massive black hole merger ever observed, following a collision between two giant black holes over 10 billion light-years from Earth, researchers announced Monday.
Each black hole was more than 100 times the mass of the sun and spiraled into one another before merging into a new black hole estimated to be around 265 times the mass of our sun, according to data from the US-based Laser Interferometer Gravitational-wave Observatory (LIGO).
“These are the most violent events we can observe in the universe, but when the signals reach Earth, they are the weakest phenomena we can measure,” Professor Mark Hannam told The Guardian, adding: “By the time these ripples wash up on Earth they are tiny,” referring to theories that the two black holes may have formed from earlier mergers.
Black holes typically form when massive stars exhaust their nuclear fuel and collapse at the end of their lifespans, forming a massive gravity well that captures anything that gets near enough to it.
In this case, the record-breaking black hole merger has challenged current theories on how such massive objects form, with Earth-based detectors capturing faint space-time ripples smaller than a proton. The new black hole is also spinning at nearly the theoretical limit – around 400,000 times faster than Earth.
The space-time ripples, or gravitational waves, reached Earth on Nov. 23, 2023, when LIGO detectors in the US states of Washington and Louisiana recorded simultaneous signals. The detectors captured a brief distortion lasting one-tenth of a second – known as the ringdown phase – when the newly formed black hole settled.
“These are the highest masses of black holes we’ve confidently measured with gravitational waves,” said Hannam, a LIGO collaboration member.
“And they’re strange, because they are slap bang in the range of masses where, because of all kinds of weird things that happen, we don’t expect black holes to form.”
LIGO physicists believe the black holes were likely formed from earlier mergers, explaining their massive size and rapid spin. “This is the most extreme example where that’s probably what’s happening,” said Hannam.
He added: “The detectors we have planned for the next 10 to 15 years will be able to see all the black hole mergers in the universe, and maybe some surprises we didn’t expect.”
