(ORDO NEWS) — Astronomers have discovered a very unusual black hole that may be older than all stars and galaxies.
Astronomers have discovered a very unusual black hole. She belongs to the almost elusive “middle class” of these space monsters. Even more surprising, this celestial body may be the same age as the Universe.
Scientists are well aware of two types of black holes. First, these are black holes of stellar mass (up to 65 suns), formed during supernova explosions. Secondly, these are supermassive black holes with a mass of millions and billions of suns, nestled in the centers of large galaxies.
Theoretically, the gap between them should be filled with black holes of average, or intermediate, mass. However, astronomers rarely manage to find such objects.
Only in 2020, gravitational wave observers detected the merging of black holes with a mass slightly larger than the stellar one. Scientists have also reported the discovery of medium-mass black holes from their X-rays. But nevertheless, the “middle peasants” remain exotic and poorly studied objects.
The authors of the new study report the discovery of a black hole with a mass of 55 thousand suns by a new and very unusual method. The elusive predator served as a gravitational lens for a gamma-ray burst – a burst of cosmic gamma-ray radiation.
Relatively speaking, a match flashed very far in space. The black hole lens collected the light from this flash and focused it. Thanks to this, scientists discovered not only the flash itself, but also a dark body that played the role of a lens.
Gamma-ray burst GRB 950830 was recorded back in 1995. But now the experts have re-processed the data using the latest algorithms and discovered something that they had not noticed before. The same flash was recorded not once, but twice. Moreover, it was not a repeated splash, but a reproduction of the previous one in the smallest detail.
This is possible only in one case: if a gravitational lens appeared in the path of gamma rays, which formed two images instead of one. Calculations have shown that this lens is a black hole with a mass of 55 thousand suns.
Various scientific groups have reported a similar phenomenon several times, but this was the first time it was discovered quite reliably. The probability that the signal is a “false alarm” is less than 1%.
Intermediate-mass black holes are interesting not only because they are poorly understood. Among them, there may be primordial black holes formed in the first second after the Big Bang, that is, long before the formation of atoms, not to mention the stars and planets. Astronomers have never observed such “relics”, and such a discovery would undoubtedly go down in the history of science.
“This newly discovered black hole may be an ancient relic – a primordial black hole that appeared in the early universe before the formation of the first stars and galaxies,” says study co-author Eric Thrane of Monash University.
However, a medium-mass black hole is not necessarily primary. It could have formed much later. How such objects are born and grow is a separate question, to which scientists have yet to find an answer.
The authors of the new study solved another interesting problem. They asked themselves: how many “middlings” must be hiding in the vicinity of the Milky Way so that in 1995 astronomers had a chance to stumble upon gamma-ray burst lensing? After all, the latter have not been studied so long ago by science.
Calculations have shown that in the vicinity of the Galaxy there should be about 46 thousand black holes of intermediate mass. And if so, new discoveries may await us ahead.
A scientific article with the results of the study was published in the journal Nature Astronomy.
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