How The Largest Black Hole Merger In History Challenges Its Physics

NDTV

17-07-2025

Astronomers have detected the largest black hole merger ever, and it has challenged their understanding of such formations. The event, designated GW231123, was initially detected on November 23, 2023, by the LIGO-Virgo-KAGRA (LVK) Collaboration.
Two enormous black holes, around 100 and 140 times the mass of the Sun, collided in this cosmic collision to create a new black hole - 225 times more massive than the Sun, per the Astronomy Magazine.
Since supernova physics usually disturbs progenitor stars in the 60-130 solar mass "mass gap," black holes in that range are not likely to develop via regular stellar collapse.
And GW231123 stands out among those 300 black hole mergers for reasons other than simply being the greatest massive collision.
"This is the largest and most massive black hole binary ever detected through gravitational waves, and it poses a real challenge to our understanding of black hole formation," LIGO Scientific Collaboration member Professor Mark Hannam of Cardiff University asserted.
The distance of GW231123 from Earth is unknown; it may be as far away as 12 billion light-years, according to Professor Hannam. The speed at which the two black holes are orbiting one another is another unexpected aspect of GW231113.
The results showed that the two merging black holes were spinning close to the maximum allowed by general relativity, in accordance with Einstein's theory. It is, thus, quite challenging to extract exact features and to model waveforms with such high angular momentum.
The black holes are probably spinning as rapidly as is practically feasible, according to Dr Charlie Hoy of Portsmouth University. "GW231123 poses a serious threat to our knowledge of how black holes emerge," Dr Hoy said.
According to Professor Zoltan Haiman of the Institute of Science and Technology Austria, who was not involved in the project, the black holes in GW231123 were therefore thought to be leftovers of one or even several generations of previous mergers.
GW231123 was discovered by a group of astronomers when the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected faint ripples in space-time caused by two black holes colliding. Scientists refer to these disturbances as gravitational waves.
The event was detected during the fourth observing run of the LIGO-Virgo-KAGRA (LVK) network, which consists of Japan's KAGRA, the Virgo detector in Italy, and the LIGO observatories in the United States, CNN reported.
GW190521, which was only 60 per cent as large as GW231123, held the previous record for the largest black hole merger ever recorded. In the future, scientists may discover even more gigantic mergers.