General, Research, Technology

Physicists have discovered a merger of black holes that should not exist

Seven billion years ago, somewhere on the edgeUniverse, there was a collision of two giant dark objects. This event sheds light on the invisible process of the accelerating expansion of the Universe: vibrating in space-time, two supermassive black holes made a loud, abruptly breaking sound. The signal lasted a tenth of a second, but this was enough for the detectors of the LIGO interferometric gravitational-wave observatory and the VIRGO interferometric observatory to record it. As the authors of new studies write, a short signal from a distant galaxy raises many questions, especially in areas related to the formation and evolution of black holes. One, or possibly both, colliding holes were too massive and could not form as a result of the collapse of neutron stars. What's more, the merger has spawned an even larger black hole, which is 142 times the mass of the Sun and should not exist according to standard models. But how is this possible?

A black hole merger simulation looks like this

Anomalous black holes

Black holes predicted by Albert Einsteinthese are massive objects, the gravitational attraction of which is so great that even photons of light cannot leave them. The existence of these mysterious objects was proved in 2015, after the observatories LIGO and VIRGO recorded gravitational waves - ripples in space-time that appeared as a result of the collision of two supermassive black holes. Read more about the discovery that brought the Nobel Prize in physics to the founders of LIGO in the material of my colleague Artem Sutyagin.

Most of the known black holes are deadmassive stars that have collapsed into objects several times more massive than the Sun. But inside galaxies, there are black holes millions or billions of times more massive than our home star. How did these objects grow to this size - the eternal mystery of astronomy.

At the end of your life, when the stars run outnuclear fuel and they no longer resist their own gravity, they collapse (collapse). Low-mass stars, including our Sun, eventually become faint stellar ghosts known as "white dwarfs." Stars that are about 8 times the mass of the Sun become incredibly dense and small objects called neutron stars. And truly massive stars over 20 solar masses at birth become black holes, with finite masses ranging from a few to about 40 solar masses.

Until recently, researchers did notthere is a lot of evidence of the existence of black holes of average and, let's say, intermediate sizes, whose mass exceeds the solar mass by 100 and 100,000 times. The black hole created by the merger of such massive objects is the first convincing example of the existence of this "missing link" in astronomy.

The image shows ripples of space-time and a short beep

The New York Times quoted the words immediatelyseveral scientists who did not participate in the research. For example, astrophysicist from Northwestern University Vicki Kalorega wrote in an email: “This is the first and only reliable measurement of the mass of a medium-sized black hole at the time of its birth. We now know for certain that at least one way these objects can be formed is by merging other black holes. "

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According to Sergei Klimenko, a physicist at the University of Florida, the discovery is also an important milestone in gravitational wave astronomy. The scientist has been looking for these objects for the past 15 years. The researcher noted that astronomers may havegot an idea of ​​the process by which the Universe "builds" black holes in the dark, turning tiny objects into rumbling leviathans.

Daniel Holtz, theoretical physicist from Chicagouniversity and a member of the LIGO team, called the new work "the first truly amazing LIGO / Virgo discovery." Previously discovered other binary systems, according to the scientist, fit well enough into expectations. But in this case, such massive black holes should not exist!

An international group of researchers included ina member of the LIGO and Virgo collaborations, reported their findings in two papers published in Physical Review Letters and Astrophysical Journal Letters. According to the results obtained, the events unfolded at an almost unimaginable distance from Earth - 17 billion light years. One black hole has a mass 85 times the mass of the Sun, and the second, whose mass is 66 times the mass of our home star, merged together in a collision, creating a black hole 142 times more massive than the Sun.

As the authors of the study note, this processThe merger could be an important clue to the origin of the more massive of the two black holes. Presumably, the black hole GW190521 had a mass of 85 Suns, and, according to standard astrophysical logic, should not have existed. Black holes with masses of 50 to 120 suns cannot form, at least from a dying star - this is precisely what history and calculations show.

Secrets of massive stars

Researchers have suggested for quite some timethat something strange is happening to very, very massive stars, perhaps those whose initial masses are between 130 and 250 solar masses, whose cores get really hot (about a billion degrees Kelvin) at the end of stellar evolution. The light reflected inside these stars is so energetic that it can transform into pairs of electrons and positrons (positrons are the antimaterial counterparts of an electron - they are almost identical, but have the opposite charge).

"Medium" black holes are the missing link in astronomy

This, in turn, makes the star unstable: pressure suddenly drops, the center of the star shrinks and heats up, and a fleeting nuclear fusion causes the entire star to explode in a bright supernova "pair instability" leaving no remnants behind.

Interesting: Black holes can be used as a source of infinite energy

As Dr. Holtz notes, the big black holeis right in the middle of an area where black holes don't belong. Nature seems to have ignored all of our careful theoretical calculations, arguing that black holes of this mass do not exist. He added: “Discoveries like these are both discouraging and arousing interest. On the one hand, one of our main beliefs turned out to be wrong. On the other hand, there is something new and unexpected in this, and now the race continues, because you have to try to figure out what is happening.

According to Dr. Holz and others, the mostintriguing is the possibility that the overly massive black hole GW190521 was formed by two smaller black holes that collided and merged. In this case, the merger observed in June 2020 would be a second or even third generation event, one in a hierarchical series of black hole mergers that eventually lead to supermassive black holes. Some astrophysicists believe such mergers are likely to occur near the centers of galaxies, where supermassive black holes create swirling spirals of gas and other objects in which thousands of smaller black holes can gather and multiply.