The explosion, dubbed AT2021lwx, occurred nearly 8 billion light-years from Earth when the universe was about 6 billion years old and is still being detected by a network of telescopes
Posted Date – Fri, 12 May 23 at 05:59pm
PHOTOGRAPH BY MARK A. GARLICK / UNIVERSITY OF SHEFFIELD / AFP
New Delhi: Astronomers say they have detected the largest cosmic explosion ever recorded, which has now lasted more than three years.
The explosion, known as AT2021lwx, occurred nearly 8 billion light-years away from Earth when the universe was about 6 billion years old and was still being detected by a network of telescopes, the researchers said.
They say the explosion was more than ten times brighter than any known supernova or exploding star, and three times brighter than the brightest TDE, in which a star falls into a supermassive black hole.
According to the researchers, the event has now lasted more than three years, compared to most supernovae, which are only visible for a few months.
“We found it by accident because it was flagged by our search algorithm when we searched for a type of supernova,” said Philip Wiseman, a researcher at the University of Southampton and the Royal Astronomical Society.
“Most supernovae and TDEs last only a few months before disappearing. It is very unusual for something to stay bright for more than two years,” Wiseman said in a statement.
The team believes the explosion was the result of a massive cloud of gas — possibly thousands of times larger than the sun — being violently disrupted by a supermassive black hole.
Fragments of the cloud would be engulfed, sending shock waves through its remnants and into a large dusty “doughnut” around the black hole. Such events are very rare and nothing of this magnitude has been seen before.
Last year, astronomers witnessed the brightest explosion ever recorded — a gamma-ray burst known as GRB 221009A. While this was brighter than the AT2021lwx, it only lasted for a fraction of the time, meaning the total energy released by the explosion of the AT2021lwx was much greater.
AT2021lwx was first detected in 2020 by the Zwicky Transient Facility in California, USA, and was subsequently received by the Asteroid Terrestrial Impact Last Alert System (ATLAS) in Hawaii.
These facilities survey the night sky to detect transient objects that change rapidly in brightness, which indicate cosmic events such as supernovae, and to search for asteroids and comets.
However, the scale of the explosion was unknown until now.
There are different theories as to what might have caused this explosion, but the team believes the most plausible explanation is that an extremely large cloud of gas (mainly hydrogen) or dust was de-orbited from orbit around the black hole and sent in.
The researchers are now setting out to collect more data on the explosion — measuring different wavelengths, including X-rays, that can reveal the object’s surface and temperature, as well as the underlying processes that were taking place.
They will also perform upgraded computational simulations to test whether those simulations match their theories about the cause of the explosion.
