A giant black hole came to life, turning into the brightest object ever seen
For the first time in observational history, scientists were able to see an ancient J221951 black hole, which came to life and transformed from a dim to an unusually bright object in a cosmic blink of an eye. This hole is about 10 billion light-years from Earth, so the flash itself occurred when the universe was about a quarter of its current age.
This is according to a study to be published in the Monthly Notices of the Royal Astronomical Society journal. For now, the scientists' article is available on the preprints site arXiv.
According to the authors of the study, even though J221951 is too far from Earth, it flashed so strongly that astronomers initially took it for a stellar explosion at a distance of less than 1 billion light years.
Thus, the researchers note, a powerful explosion like this makes this black hole one of the brightest transients (suddenly bright and then fading) ever detected.
The first sign of something extreme that astronomers discovered was a gravitational wave, i.e. a rapid ripple in space-time generated by the most massive cosmic collisions. Scientists hypothesized that it was the result of a collision between two dense, dead stars known as neutron stars. Such collisions result in explosions called a kilonova.
Subsequently, they traced the source of the wave as well. They realized that it was some other cosmic object, because a kilonova first looks blue and then fades to red within a few days, while that specific hole remained bright and blue for months.
Further observations from several telescopes, particularly NASA's Hubble Space Telescope and the Neil Gehrels Swift Observatory, showed that the mysterious object aligned with the center of a dim and distant galaxy could be a supermassive black hole similar to the one at the center of the Milky Way.
According to Live Science, after 10 months of brightness, the object has finally begun to fade again, proving that it is not a galaxy, but a transient object experiencing an intense, high-energy burst.
"Our understanding of the different things supermassive black holes can do has expanded considerably in recent years," said study co-author Matt Nicholl, an astronomer at Queen's University Belfast.
According to him, J221951 is "one of the most extreme examples of a black hole taking us by surprise."
As for the reasons for this strange behavior of the black hole, scientists have two theories. According to one, the black hole could pull an orbiting star into its captivity, stretching it and tearing it to shreds. The second version is that scientists saw the black hole come to life, going from a state of rest to a state of active feeding, when it suddenly began to absorb the fast-moving gas disk surrounding the hole.
Figuring out exactly why the black hole came to life will require further research.
As the scientists point out, if the black hole suddenly becomes brighter again, this means it is probably in feeding mode. But if it fades permanently, it is likely that some unfortunate star has been consumed in the most spectacular way imaginable.
OBOZREVATEL also previously told us that black holes can work as a time machine.