The international LIGO collaboration announced the detection of the largest black hole merger ever recorded. This event, dubbed GW231123, occurred on November 23, 2023, and the resulting black hole, resulting from the merger of two supermassive black holes, had a mass 225 times that of the Sun.
A merger of this magnitude is considered impossible according to current models of stellar evolution. The findings have prompted a reassessment of scientific approaches to how black holes form.
GW231123 Surprises the Scientific World
Gravitational waves are defined as perturbations in spacetime that propagate at the speed of light, resulting from violent events, much like the rings formed by a stone thrown into water.
However, some events reveal not only the traces of these waves but also their direct and powerful effects in a detectable way. LIGO, the Laser Interferometric Gravitational Wave Observatory, measured these waves for the first time in 2015, making a groundbreaking discovery in scientific history.
Since then, LIGO, along with the Virgo observatories in Europe and the KAGRA observatory in Japan, has regularly monitored the sky. Numerous cosmic signals have been detected to date, including approximately 300 black hole mergers.
However, GW231123 stands out among these observations. In this event, two black holes, 137 and 103 times the mass of the Sun, respectively, merged at extremely high rotation rates, creating a new supermassive black hole with a mass of 225 solar masses.
For comparison, the record-holding merger of GW190521, recorded in 2019, had a mass of approximately 140 solar masses. The fact that the signal lasted only 0.1 seconds and was clearly detected by LIGO within such a short time suggests that the merger was extremely intense and stable.
Mark Hannam, a physicist at Cardiff University and a member of LIGO, stated that such mergers are impossible according to current models of stellar evolution and that they are considering the possibility that the black holes may have formed from previous mergers.
Charlie Hoy, a physicist at the University of Portsmouth and another member of LIGO, stated that the black holes involved in the merger were rotating at speeds very close to the maximum rotation speed predicted by Einstein’s theory of general relativity. He emphasized that this makes modeling and interpretation of the resulting signal extremely complex, but also presents a significant opportunity to improve theoretical physics tools.
Scientists will present the data on GW231123 next week at the General Relativity and Gravitational Waves Conference (GR24 and Amaldi16) in Glasgow, Scotland. Following this presentation, the data will be made public, and the details of the event will begin to be thoroughly studied by the scientific community.
University of Birmingham physicist Gregorio Carullo stated that the complex structure of the signal could take years to unravel. While black hole mergers are thought to be the underlying cause, more complex cosmic scenarios are thought to play a significant role in explaining these unusual features.
Gravitational waves stand out as one of the rare methods that allow the observation of cosmic events without the need for light. This feature makes them a unique observational tool for understanding black holes, ancient stars, and even dark matter.
