Robert Lea
Astrophysicists use LIGO-Virgo-KAGRA (LVK) detectors to capture gravitational waves from the largest known merger black holes in history on the outskirts of the Milky Way galaxy.
The resulting black hole is 225 times more massive than our Sun. The researchers were most interested in the masses of the merged black holes, which are about 100 and 140 times the mass of the Sun. Black holes of this size fall into the so-called «mass gap», which challenges the generally accepted notion of the formation of space-time discontinuities.
«We expect that most black holes are formed by the death of stars. If the star is massive enough, it will collapse into a black hole. But for really massive stars, our theories say that the collapse is unstable, and most of the mass is ejected in supernova explosions, so a black hole cannot form. We do not expect the formation of black holes with a mass of 60 to 130 solar masses In this observation, the black holes appear to be in this mass range», — indicates professor of physics at Cardiff University in Wales and a member of the LVK collaboration Mark Hannam.
Black holes are formed as a result of the collapse of massive stars and grow larger by absorbing gas, dust, stars, and other black holes. Currently, scientists are divided into black holes into two categories — black holes with masses ranging from several to several tens of solar masses, and supermassive black holes — whose masses can range from 100 thousand to 50 billion solar masses. However, those that fall in between these two mass ranges, known as intermediate-mass black holes, are physically incapable of forming as a result of a direct stellar collapse and are therefore extremely rare. However, astrophysicists have discovered evidence of their existence and suggested that they could be formed by merging with other black holes.
Evidence of such a merger was obtained from On November 23, 2023, when the detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Louisiana and Washington, DC, have picked up the corresponding gravitational waves. Both detectors, each of which has two L-shaped arms 4 kilometers long with two identical laser beams, are designed in such a way that when a gravitational wave passes through the Earth, the laser beam in one arm of the detector shrinks and expands in the other, which leads to to a small change in the relative length of the ray path.
The signal picked up by the detectors came from two massive black holes that were rapidly rotating around their own axis. Astronomers typically analyze black hole mergers by modeling signals from different types of black hole binaries before comparing them to any newly detected signal. However, this method will only be effective if the model is accurate, and Einstein’s equations are more difficult to solve when black holes are moving rapidly.
«The black holes in GW231123 appear to be rotating at high speeds, and our different models give different results. This means that, although we are sure of the enormous mass of black holes, we cannot measure their masses accurately enough. For example, the possible masses of a smaller black hole cover the entire mass interval», — explains Mark Hannem.
To accurately calculate the masses of black holes, astrophysicists will need to improve their own models. The LIGO, Virgo, and KAGRA gravitational wave detectors have recorded 300 mergers since the first launch in 2015, and only 200 mergers were detected in the fourth launch.
Source: LiveScience