Astronomers have detected the most powerful cosmic explosion ever seen – a mysterious, multi-year explosion that is 10 times brighter than any observed supernova. Astronomers detected the event called AT2021lwx 8 billion light-years from Earth. The strange explosion, which released about 100 times more energy than the Sun during its lifetime, began when the universe was 6 billion years old.

“We came across it by chance because it was flagged by our search algorithm when we were looking for a type of supernova,” said lead author of the study, Philip Wiseman, an astronomer at the University of Southampton in the United Kingdom. “Most supernova and tidal disruption events [яскраві спалахи, які виникають, коли чорні діри розривають блукаючі зірки] lasts only a few months before fading. For two and a half years, it suddenly became unusual for things to be bright.”

The cause of the mysterious explosion is unknown, but astronomers believe it was most likely the result of a supermassive black hole swallowing a giant hydrogen cloud thousands of times the size of our Sun.

As parts of the cloud are sucked in, shock waves travel through the remnants of hot gas, causing a giant explosion whose light has bombarded Earth for more than two years and has not yet extinguished. Using two telescope systems designed to scan the entire sky—the Zwicky Transient Facility in California and the Asteroid Terrestrial Impact Final Warning System (ATLAS) in Hawaii), researchers detected the bright flashing light of a distant event.

Black holes are born from the collapse of giant stars and grow out of gas, dust, stars and other black holes. For some of these voracious space-time rifts, friction causes material spiraling into their mouths to heat up and emit light detectable by telescopes, turning them into so-called active galactic nuclei (AGN).

The most extreme AGNs are quasars, supermassive black holes billions of times heavier than the sun, that eject cocoons of gas in bursts of light trillions of times brighter than the brightest stars.

However, despite the quasar’s brilliance, the explosion is too short-lived to be single.

“With a quasar, we see the brightness rise and fall over time. But in retrospect, the AT2021lwx went undetected for more than a decade and then suddenly appeared with the brightness of the brightest things in the universe, which is unprecedented,” he said. This means that the explosion likely came from a cloud of gas that initially safely orbited the black hole, but deviated from its course to be drawn into the mouth of the space monster.

To confirm the identity of the object that caused the explosion, the researchers are now studying the explosion in more detail by scanning wavelengths. This can reveal the mysterious processes that create surface shape, temperature, and bright light. The researchers published their findings in a journal. Monthly Notices of the Royal Astronomical Society.