Largest observed flare from a black hole unleashes the light of 10 trillion suns

Astronomers have spotted the largest and most distant flash ever seen from a supermassive black hole. The flare, nicknamed “Superman”, originated 10 billion light-years from Earth, and at its peak the light emitted was as bright as 10 trillion suns.

The source of the flare is the active galactic nucleus, or AGN—the bright, compact region at the center of the galaxy—and it is fed by a supermassive black hole that is actively feeding on material. Gas and dust fall into a spinning disk around the black hole, and as the debris spirals faster, it overheats, releasing intense radiation.

Researchers wondered what the giant black hole swallowed to release such a powerful flare. They concluded that it likely devoured a massive star that would otherwise have been destined to end its life in an explosion.

“About 1 in 10,000 AGN exhibits some kind of flare activity, but it is so extreme that it is in its own category (which is about 1 in a million events),” 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 of the unprecedented phenomenon published Tuesday in the journal. Nature Astronomy.

The flare suggests the presence of unknown populations of giant stars near the centers of large galaxies that also host supermassive black holes, and sheds light on the complex interactions between the two giants.

Large-scale star celebration

Superman was first discovered through real-time transient research by Catalina and the Zwicky Transient Center at the Palomar Observatory in Southern California in November 2018. Zwicky, who scans the night sky with a wide-angle camera, has a reputation for allowing astronomers to detect transients or fleeting cosmic phenomena such as rapidly exploding supernovae.

According to Graham, at first the object did not seem unusual, just bright. The team of astronomers thought it was a blazar, or supermassive black hole, that was shooting energetic jets of material across space.

Five years later, they revisited early data collected from Zwicky's study and noticed one signal, previously thought to be a blazar, that was constantly changing in brightness. The team made follow-up observations using other telescopes such as the V.M. Keck in Hawaii, which showed that the light source was brighter and more energetic than originally thought.

Light, they realized it came from an active galactic nucleus that is estimated to be 500 million times more massive than our Sun.

Astronomers looked at several possible reasons why the flare was so bright, such as the explosion of a massive star inside a disk of material around the black hole, before determining that the most likely cause was tidal disruption, where a star gets too close to the black hole and is torn apart.

The flare is ongoing, meaning the black hole is still actively consuming the star, like “a fish only halfway down a whale's esophagus,” Graham said.

Superman reached a maximum brightness that was 30 times brighter than any other known black hole flare, and the mass of the star being consumed by the black hole is at least 30 times the mass of the Sun. The previous tidal disruption record was set by ZTF20abrbeie, nicknamed “Scary Barbie”. It was caused by a black hole consuming a star that was 3 to 10 times the size of our Sun.

“This is likely the most massive star ever seen destroyed by a supermassive black hole,” study co-author C. E. Saavik Ford, a professor of astronomy at Community College of Manhattan and a research fellow in the department of astrophysics at the American Museum of Natural History in New York, said in a statement. “This is interesting because it tells us that massive stars must live in and around gaseous disks around supermassive black holes.”

Look into the hearts of galaxies

The team continues to monitor the flare, which fades over time, although time moves differently near the black hole than on Earth, Graham said.

“This phenomenon is called cosmological time dilation due to the stretching of space and time. As light moves through expanding space to reach us, its wavelength is stretched, just like time itself,” he said. “Seven years here, two years there. We're watching events play out at quarter speed.”

Because the flash occurred 10 billion light years away, the light took 10 billion years to reach Earth. A light year is the distance that light travels in one year, that is 5.88 trillion miles (9.46 trillion kilometers).

By studying the Zwicky data and using new telescopes such as the Vera K. Rubin Observatory in Chile, it may be possible to identify more of these rare events, which demonstrate that supermassive black holes have dynamic environments and are much more than just large funnels surrounded by swirling material, Graham said.

According to Ford, such flares reveal the presence of incredibly large stars near the hearts of galaxies and shed light on the very structure of galaxies.

“Understanding the stars at the centers of galaxies (how many there are and what kind they are) at such early times in the Universe gives us a new way to study the assembly of galaxies as a whole,” she said.

The discovery represents an amazing leap in our understanding of the most powerful events in the universe, said Dr. Danny Milisavljevic, assistant professor of physics and astronomy at Purdue University. Milisavljevic was not involved in the new study, but has previously researched the Scary Barbie event.

“We once thought 'Scary Barbie' was a freaky, one-of-a-kind anomaly, but this new flare is even more extreme, releasing as much energy as if the entire Sun had turned completely into electromagnetic radiation,” he wrote in an email.

“It belongs to the recently emerging class of extreme nuclear transients (ENT), a poorly understood phenomenon that challenges our current models of black hole-star interactions.”

The flare provides insight into the growth of black holes, how they tear apart nearby stars and how their enormous energy can shape the galaxies around them, said Alex Filippenko, a distinguished professor of astronomy at the University of California, Berkeley. Filippenko was not involved in the new research, but his work laid a solid foundation for active physics of galactic nuclei.

“When a supermassive black hole suddenly erupts in a brilliant flash, it gives astronomers a front-row seat to some of the most extreme physical phenomena in the Universe,” he wrote in an email. “With this record-breaking clearing, astronomers have opened a new window into the extreme physics of galactic centers, where stars, gas and gravity collide in the most brutal laboratories of the universe.”

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