A team of astronomers have identified the largest cosmic explosion ever witnessed.
The researchers from the University of Southampton in England say the explosion, known as AT2021lwx, is ten times brighter than any known exploding star, or supernova, and three times brighter than the flash that occurs when a star is consumed by a supermassive black hole, which is known as a tidal disruption event.
"We came upon this by chance, as it was flagged by our search algorithm when we were searching for a type of supernova,鈥� lead author and University of Southampton research fellow Philip Wiseman said in a . 鈥淢ost supernovae and tidal disruption events only last for a couple of months before fading away. For something to be bright for two plus years was immediately very unusual.鈥�
Now over three years old, the AT2021lwx explosion was first detected in 2020 by observatories in California and Hawaii that scan the night sky for objects that rapidly change in brightness, like supernovae, asteroids and comets. AT2021lwx was then studied further with a space-based telescope and observatories in Chile and Spain.
AT2021lwx, which is still being tracked, is nearly 8 billion light years away. Scientists believe it is the result of a vast cloud of mostly hydrogen gas or dust being violently consumed by a supermassive black hole. While brighter cosmic explosions have been recorded in the past, they lasted a fraction of the time and released much less energy overall, meaning that nothing of this scale has ever been witnessed before.
"Once you know the distance to the object and how bright it appears to us, you can calculate the brightness of the object at its source," study co-author and University of Southampton astrophysics professor Sebastian Hönig said in the release. "Once we鈥檇 performed those calculations, we realized this is extremely bright."
The only things in the universe known to be as bright as AT2021lwx are quasars, which are supermassive black holes emitting large amounts of energy as they feed on gas at the centre of galaxies.
"With a quasar, we see the brightness flickering up and down over time," study co-author and University of Southampton astronomer Mark Sullivan explained. "But looking back over a decade there was no detection of AT2021lwx, then suddenly it appears with the brightness of the brightest things in the universe, which is unprecedented."
The researchers' findings were published Friday in .
"With new facilities鈥� coming online in the next few years, we are hoping to discover more events like this and learn more about them," Wiseman, the lead author, said. "It could be that these events, although extremely rare, are so energetic that they are key processes to how the centres of galaxies change over time."
