A black hole 10 billion light years away suddenly showed its brightness to be one of the brightest temporal objects ever detected. This event occurred in the early Universe, when the Universe was about a quarter of its present age. Despite its vast distance, the black hole glowed so strongly that astronomers first mistook it for a stellar explosion at a closer distance.
Researchers have named this black hole J221951 and believe it is about 10 billion light-years from Earth. This means that the light from this cosmic monster reached us after traveling a huge distance and time. It also means that the black hole turned on its light when the universe was very young.
Why did this black hole become so bright? Researchers speculate two possible reasons. First, the black hole may have absorbed a spinning star, ripping it to shreds through a process called tidal disruption or “spaghettification. The second possibility is that the black hole went from a resting state to an active feeding state, beginning to absorb the rapidly moving gas disk surrounding it.
“Our understanding of the various things supermassive black holes can do has expanded considerably in recent years,” says Matt Nicholl, an astronomer at Queen’s University Belfast. “J221951 is one of the most extreme examples of a black hole catching us off guard.”
The researchers were first surprised when they traced the path of a gravitational wave, a fast-moving ripple in space-time. They hypothesized that this wave was released during the collision of two dense dead stars, neutron stars that are known for their bright explosions, called kilonova explosions.
The ripple in spacetime did indeed result in a bright object. However, unlike the kilonova, which first appears blue and then fades to red within a few days, this object remained bright and blue for months – much longer than stellar explosions usually are.
Further observations from several telescopes, including NASA’s Hubble Space Telescope and the Neil Gehrels Swift Observatory, showed that the mysterious object coincides with the center of a dim and distant galaxy. This suggests that it may be a supermassive black hole, very similar to the one at the center of the Milky Way.
After 10 months of brightening, the object finally began to dim, proving that it was a temporary object undergoing an intense high energy burst.
Figuring out why the black hole “turned on” will require further research into the object’s energy output. If the black hole becomes bright again, this would mean that it is probably in power mode. But if it fades permanently, it could mean that some unfortunate star was absorbed in a most spectacular way.
The study of black hole J221951 is an important step in our understanding of supermassive black holes and their behavior. It also underscores the importance of modern technology and instruments that allow astronomers to study such distant and powerful objects.
