'Terrifying': Why the universe's largest cosmic explosion is called 'Scary Barbie'

  • Astronomers are wowed by what they describe as the largest cosmic explosion ever seen.
  • The event is more than 10 times brighter than a supernova and 100 times the size of our solar system.
  • Researchers think a supermassive black hole is either engorging a giant mass of gas or ripping apart a star.

They call it "Scary Barbie." But it's not a new toy, it's a cosmic event astronomers agree is the largest explosion and brightest event ever witnessed in the universe.

But two teams of researchers have arrived at different explanations for the explosion, the brilliance of which has lasted for more than three years.

The explosion is more than 10 times brighter than any known supernova, which is the dying of a massive star and the largest explosion in space, and three times brighter than the brightest tidal disruption event, in which a black hole tears apart a star and flings debris away.

When the space object was first detected in 2020 by the Zwicky Transient Facility in California, it was given the random name of "ZTF20abrbeie," and as it's gained attention also gained the nickname of “Scary Barbie.” It also earned the name "AT2021lwx," when it was picked up by the facility in 2021 as a transient object which changes in brightness dramatically or appears or disappears.

“We came upon this by chance, as it was flagged by our search algorithm when we were searching for a type of supernova,” says Philip Wiseman, an astrophysicist at the University of Southampton, U.K., who led the research published in the Monthly Notices of the Royal Astronomical Society. “Most 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.”

Is the largest known cosmic explosion a case of too much gas?

There are different theories about what caused the explosion, which took place nearly eight billion light years away when the universe was about six billion years old.

But the team led by Wiseman speculates that a gigantic cloud of gas, mostly hydrogen, or dust had been orbiting a black hole and veered off course into it.

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They believe the explosion is "a result of a vast cloud of gas, possibly thousands of times larger than our sun, that has been violently disrupted by a supermassive black hole," the researchers say in a press release describing the findings. "Fragments of the cloud would be swallowed up, sending shockwaves through its remnants, as well as into a large dusty ‘doughnut’ surrounding the black hole. Such events are very rare and nothing on this scale has been witnessed before."

The overall energy released by this explosion is far greater than that of the brightest explosion on record – a gamma-ray burst known as GRB 221009A reported last year by astronomers. The explosion was brighter but lasted only a fraction of the amount of time as "Scary Barbie," which is still being observed.

The energy produced by "Scary Barbie" is about that of a “fireball 100 times the size of the solar system” Wiseman told The Guardian. “In three years, this event has released about 100 times as much energy as the sun will in its 10bn-year lifetime.”

Artist’s impression of a black hole accretion. Astronomers have witnessed the universe's largest explosion ever and a team of astronomers led by the University of Southampton believe its caused by a supermassive black hole disrupting a vast cloud of gas, possibly thousands of times larger than our sun.

Or could 'Scary Barbie' be the celestial drama of a black hole devouring a star?

Another explanation is offered by researchers at Purdue University’s College of Science: a supermassive black hole is ripping apart a star.

"The forces around a black hole, called tidal disruption, pull other objects apart in a process called ‘spaghettification.’ We think that’s what happened, but on extreme time scales: The most massive of black holes ripping apart a massive star," said researcher Bhagya Subrayan in a Purdue University news release. Subrayan is a graduate student on the team led by Danny Milisavljevic, an assistant professor of physics and astronomy at the school, whose findings have been accepted for publication in The Astrophysical Journal Letters.

Researchers didn't find "Scary Barbie" until recently because it is far away in a "somewhat neglected corner of the sky," they say. Computers didn't raise an alarm about it because it didn't fit standard concepts of galactic events.

"This is so different from anything else we’ve ever seen that we hadn’t even gotten around to trying to classify it," Milisavljevic said. "It's been hanging out in the public data for years.”

Eventually, Milisavljevic’s lab’s AI engine identified it as something worth further study. Like the Southampton researchers, they used data from other telescopes to assess "Scary Barbie."

About that name, Milisavljevic said the object is “scary” because, "it’s so much of an outlier; its characteristics are terrifying.”

“Scary Barbie” is the affectionate nickname astronomers are calling one of the most energetic and luminous transients ever observed: a supermassive black hole tearing apart a massive star.

How will we learn the cause of the cosmic explosion?

Researchers will continue to study telescope data to learn more about "Scary Barbie."

“With new facilities, like the Vera Rubin Observatory’s Legacy Survey of Space and Time, coming online in the next few years," Wiseman said in an email interview. "we are hoping to discover more events like this and learn more about them. 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."

But another astrophysical researcher, Matt Nicholl at Queen's University Belfast, Northern Ireland, is siding with his fellow U.K. researchers' current explanation. “At first, we thought this flare-up could be the result of a black hole consuming a passing star. But our models showed that the black hole would have to have swallowed up 15 times the mass of our Sun to stay this bright for this long,” Nicholl told IFLScience, a U.K. based science site. “Encountering such a huge star is very rare, so we think a much larger cloud of gas is more likely. Many massive black holes are surrounded by gas and dust and we are still trying to work out why this particular black hole started feeding so vigorously and so suddenly.”

The only objects in the universe as bright as the "Scary Barbie" explosion are quasars, which occur when gas and dust become luminous from falling into a supermassive black hole. “With a quasar, we see the brightness flickering up and down over time," said University of Southampton astrophysicist Mark Sullivan, one of several co-authors of the research. "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.”

Perhaps "Scary Barbie" was the beginning of a quasar phase, offered IFLScience senior staff writer and & space correspondent Alfredo Carpineti, who holds a doctorate in astrophysics from Imperial College London, in his coverage."Scary Barbie continues to shine and be observed," Carpineti wrote, "so we can expect a lot more studies to come out trying to explain this extreme cosmic event."

Follow Mike Snider on Twitter: @mikesnider.

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