The explosion – AT2021lwx – is a fireball 100 times larger than our solar system and 10 times brighter than a supernova.
Astronomers have identified the largest cosmic explosion ever observed, a fireball 100 times larger than our solar system that suddenly began blazing in the distant universe more than three years ago.
While astronomers offered what they think is the most likely explanation for the explosion on Friday, they stressed that more research is needed to understand the puzzling phenomenon.
The explosion, known as AT2021lwx, currently lasts more than three years, compared to most supernovae which are only visibly bright for a few months, according to a study published in Monthly Notices of the Royal Astronomical Society.
Led by the University of Southampton, astronomers believe the explosion was the result of a vast cloud of gas, possibly thousands of times larger than our sun, which was violently disrupted by a a supermassive black hole.
According to the study, the explosion took place almost 8 billion light-years away, when the universe was around 6 billion years old and is still detected by a network of telescopes.
Such events are very rare and nothing on this scale has been observed before, the researchers say.
Last year, astronomers witnessed the brightest explosion on record – a gamma-ray burst known as GRB 221009A, nicknamed BOAT – for Brightest Of All Time.
Although BOAT was brighter than AT2021lwx, it only lasted a fraction of the time, meaning the overall energy released by the AT2021lwx explosion was far greater.
AT2021lwx earned the nickname “Scary Barbie” from researchers due to its “terrifying energy”.
According to Danny Milisavljevic, an assistant professor of physics and astronomy at Purdue University, AT2021lwx was first given a random alphanumeric name upon discovery: ZTF20abrbeie. The nickname “Scary Barbie” comes from her alphanumeric designation “abrbeie” and “scary” due to her power.
We first thought of AT2021lwx alias ZTF20abrbeie alias #ScaryBarbie was a superluminous supernova of a massive star. But no theoretical model has come close to explaining the terrifying energy production that continues to this day. A supermassive black hole seems to be the only solution. pic.twitter.com/GldfFWltJc
— Danny Milisavljevic (@astro_dan_mil) April 26, 2023
AT2021lwx was first detected in 2020 by the Zwicky Transient Facility in California, then picked up by the Hawaii-based Asteroid Land Impact Last Warning System (ATLAS).
But until now, the scale of the explosion was unknown.
Philip Wiseman, a researcher at the University of Southampton who led the research, said: ‘Most supernovae and tidal disturbance events only last a few months before fading away. For something to be brilliant for more than two years was immediately very unusual.
It wasn’t until astronomers, including Wiseman, looked at it through more powerful telescopes that they realized what they had in their hands. By analyzing different wavelengths of light, they determined that the explosion was about 8 billion light-years away. It’s much farther than most of the other new flashes of light in the sky, which means the explosion behind it must be much larger.
It is estimated to be around 2 trillion times brighter than the Sun, Wiseman said.
Astronomers have looked at several possible explanations. The first is that AT2021lwx is an exploding star – but the flash is 10 times brighter than any “supernova” ever seen.
Another possibility is what’s called a tidal disturbance event, when a star is torn apart as it’s sucked into a supermassive black hole. But AT2021lwx is still three times brighter than those events, and Wiseman said their research didn’t point in that direction.
The only somewhat comparable bright cosmic event is a quasar, which occurs when supermassive black holes swallow huge amounts of gas at the center of galaxies. But they tend to flicker in brightness, Wiseman said, as AT2021lwx suddenly started blazing out of thin air three years ago and it’s still blazing.
“This thing that we’ve never seen before – it came out of nowhere,” Wiseman said.
Now that astronomers know what to look for, they’re scanning the skies to see if any other similar outbursts have been missed.