Astronomers have spotted the largest and most distant flare ever observed from a supermassive black hole. Nicknamed “Superman,” the flare originated 10 billion light-years from Earth, and at its peak, the light emitted shone with the brightness of 10 trillion suns.
The source of the flare is an active galactic nucleus, or AGN — a bright, compact region at the center of a galaxy — and it’s powered by a supermassive black hole that is actively feeding on material. Gas and dust fall into a rotating disk around the black hole, and as the debris spirals more rapidly, it becomes superheated, releasing intense radiation.
Researchers pondered what the gargantuan black hole consumed to release such a powerful flare. They concluded it likely gobbled up a massive star that would have otherwise been destined to end its life by exploding.
“About 1 in 10,000 AGN show some sort of flaring activity but this is so extreme that it puts it into its own category (which is roughly a 1 in a million event),” Matthew Graham, a research professor of astronomy at the California Institute of Technology, said in an email. Graham is the lead author of a study about the unprecedented phenomenon that published Tuesday in the journal Nature Astronomy.
The flare suggests there are unknown populations of giant stars near the centers of large galaxies, which also host supermassive black holes — and sheds light on the complicated interactions between two behemoths.
Superman was first detected by the Catalina Real-Time Transient Survey and the Zwicky Transient Facility at the Palomar Observatory in Southern California in November 2018. Zwicky, which scans the night sky with a wide-field camera, has a reputation of enabling astronomers to discover transients or fleeting cosmic phenomena, such as quickly flaring supernovae.
At first, the object didn’t seem unusual, only bright, Graham said. The team of astronomers thought it was a blazar, or a supermassive black hole that launches energetic jets of material across the cosmos.
Five years later, they revisited early data gathered by the Zwicky survey and noticed one signal, previously thought to be a blazar, which had steadily changed in brightness. The team captured follow-up observations with other telescopes such as the W. M. Keck Observatory in Hawaii, which revealed that the source of light was more luminous and energetic than initially thought.
The light, they realized, came from an active galactic nucleus estimated to be 500 million times more massive than our sun.
The astronomers considered several possible reasons why the flare is so bright, such as a massive star exploding within the disk of material around the black hole, before determining that the most likely cause is a tidal disruption event — when a star draws too near a black hole and gets torn apart.
The flare is ongoing, meaning that the black hole is still actively consuming the star, like “a fish only halfway down the whale’s gullet,” Graham said.
Superman peaked at a brightness that was 30 times more luminous than any other known black hole flare, and the star being consumed by the black hole has a mass at least 30 times greater than that of the sun. The previous record for a tidal disruption event was set by ZTF20abrbeie, nicknamed “Scary Barbie,” which was caused when a black hole gobbled up a star between three and 10 times the size of our sun.
“This is probably the most massive star ever seen shredded by a supermassive black hole,” study coauthor K.E. Saavik Ford, an astronomy professor at the Borough of Manhattan Community College and a research associate in the department of astrophysics at the American Museum of Natural History in New York City, said in a statement. “That’s exciting because it tells us that massive stars must live in and around gas disks around super-massive black holes.”
The team continues to monitor the flare as it fades over time — although time passes differently near a black hole compared with how it’s experienced on Earth, Graham said.
“It’s a phenomenon called cosmological time dilation due to stretching of space and time. As the light travels across expanding space to reach us, its wavelength stretches as does time itself,” he said. “Seven years here is two years there. We are watching the event play back at quarter speed.”
Since the flare occurred 10 billion light-years away, it’s taken 10 billion years for the light to reach Earth. A light-year is the distance light travels in one year, which is 5.88 trillion miles (9.46 trillion kilometers).
By combing through Zwicky’s data and using new telescopes, such as the Vera C. Rubin Observatory in Chile, it may be possible to identify more of these rare events, which showcase that supermassive black holes have dynamic environments and are far more than big sinkholes surrounded by swirling material, Graham said.
Flares such as this one reveal the presence of incredibly large stars near the hearts of galaxies and shed light on the very structure of galaxies, Ford said.
“Understanding the stars in the centers of galaxies (how many are there, what are they like) at such early times in the universe gives us a new way of investigating galaxy assembly over all,” she noted.
The discovery represents an astonishing leap in our understanding of the universe’s most powerful events, said Dr. Danny Milisavljevic, associate professor of physics and astronomy at Purdue University. Milisavljevic was not involved in the new study but previously researched the “Scary Barbie” event.
“We once thought ‘Scary Barbie’ was a bizarre, one-of-a-kind anomaly, but this new flare is even more extreme, releasing as much energy as if the entire Sun were converted completely into electromagnetic radiation,” he wrote in an email.
“It belongs to a newly emerging class of extreme nuclear transients (ENTs), a poorly understood phenomenon that is challenging our current models of how black holes and stars interact.”
The flare reveals insights into the growth of black holes, how they rip apart nearby stars and how their immense energy can shape the galaxies around them, said Alex Filippenko, distinguished professor of astronomy at the University of California, Berkeley. Filippenko did not participate in the new research, but his work has established a strong foundation for active galactic nuclei physics.
“When a supermassive black hole suddenly erupts in a brilliant flare, it gives astronomers a front-row seat to some of the most extreme physics in the Universe,” he wrote in an email. “By catching this record-breaking brightening, astronomers have opened a new window into the extreme physics of galactic centers, where stars, gas, and gravity collide in the Universe’s most violent laboratories.”
Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.