Astrophysicists detect the gravitational waves of the largest fusion of black hole to date
Using twin detectors from the NSF laser gravitational observatory (LIGO), astrophysicists with Ligo-Virgo-Kagra collaboration (LVK) detected the fusion of two black holes with the highest combined mass ever observed. Discovered on November 23, 2023 and appointed GW231123, the event produced a last black hole more than 225 times the mass of our sun.
An infographic detailing the merger of black hole GW231123. Image credit: Simona J. Miller / Caltech.
Ligo entered the story in 2015 when he made the very first direct detection of gravitational waves, ripples in space-time.
In this case, the waves emanated from a black hole fusion which resulted in a last black hole 62 times the mass of our sun.
The signal was jointly detected by Ligo twin detectors, one located in Livingston, Louisiana, and the other in Hanford, Washington.
Since then, the LIGO team has teamed up with partners of the virgin detector in Italy and the gravitational wave detector Kamioka (KAGRA) in Japan to form the LVK collaboration.
These detectors have collectively observed more than 200 mergers of black holes during their fourth round, and around 300 in total since the start of the first round in 2015.
Before now, the fusion of the most massive black hole – produced by an event which took place in 2021 called GW190521 – had a total mass of 140 times that of the sun.
In the GW231123 event, the black mass hole 225 was created by the coalescence of the black holes approximately 100 and 140 times the mass of the sun.
This places it in a rare category of black holes called intermediate mass holes – heavier than those formed from the stellar collapse, but much lighter than the supermassive black holes that are hidden in the centers of the galaxies.
In addition to their high masses, the black holes merged also quickly turned.
“It is the most massive black holes binary we have observed through gravitational waves, and this presents a real challenge to our understanding of the formation of black holes,” said Dr. Mark Hannam, astrophysicist at the University of Cardiff and member of the LVK collaboration.
“As massive black holes are prohibited by standard stellar evolution models.”
“One possibility is that the two black holes of this binary have formed through previous mergers of smaller black holes.”
“This observation shows once again how gravitational waves uniquely reveal the fundamental and exotic nature of black holes through the universe,” said Dr. Dave Reitze, executive director of Ligo at Caltech.
Researchers present the discovery of GW231123 this week 24th International Conference on General Relativity and Gravitation (GR24) and the 16th Edoardo Amaldi conference on gravitational waves held jointly at GR-AMALDI meeting in Glasgow, in Scotland.
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Ligo-Virgo-Kagra collaboration. GW231123: The most massive black hole binary detected by gravitational waves. GR-AMALDI 2025
