Mysterious flash of light was black hole jet ‘pointing directly toward Earth’

Earlier this year, astronomers at an observatory near San Diego, California made a perplexing observation: a flash of light, brighter than 1,000 trillion suns, coming from a part of the sky where they had seen only darkness the night before.

Researchers at the Massachusetts Institute of Technology now believe they have uncovered its source. In a study published Wednesday in the journal Nature Astronomy, they said a supermassive black hole had likely expelled a jet of matter as it devoured a nearby star. And the jet may be pointing directly at Earth.

The flash — first spotted at the Palomar Observatory of the California Institute of Technology — piqued the interest of astronomers across the world, who honed their telescopes on the source in hopes of determining what could release such an immense amount of light at once, MIT said in a news release.

“It was something extraordinary,” said study co-author and research scientist Dheeraj “DJ” Pasham, in a statement.

The researchers believe the flash was a “tidal disruption event,” or TDE — a star being torn apart by the colossal gravity of a black hole. Researchers have spotted other TDEs in the past. But the flash earlier this year, dubbed “AT 2022cmc,” was brighter than any ever observed, leading the MIT team to conclude that it angled toward Earth.

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The flash was detected roughly 8.5 billion lights years away — more than halfway across the universe, MIT said. It was traveling at almost exactly the speed of light.

The discovery could help scientists understand how black holes consume passing stars, said study co-author Matteo Lucchini, a postdoctoral researcher in MIT’s Kavli Institute for Astrophysics and Space Research, in a statement.

“We know there is one supermassive black hole per galaxy, and they formed very quickly in the universe’s first million years,” he said. “That tells us they feed very fast, though we don’t know how that feeding process works. So, sources like a TDE can actually be a really good probe for how that process happens.”

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Pasham said the black hole was likely in an extremely active phase — a “hyper-feeding frenzy” of consuming passing stars.

“It’s probably swallowing the star at the rate of half the mass of the sun per year,” he estimated. “A lot of this tidal disruption happens early on, and we were able to catch this event right at the beginning, within one week of the black hole starting to feed on the star.”

As more powerful telescopes become operational in the coming years, scientists could spot more TDEs, which could reveal how supermassive black holes grow and form the galaxies around them, MIT said.

“We expect many more of these TDEs in the future,” Lucchini said. “Then we might be able to say, finally, how exactly black holes launch these extremely powerful jets.”

The study’s other co-authors included MIT postdoc Peter Kosec, Assistant Professor Erin Kara, Principal Research Scientist Ronald Remillard, and collaborators at other universities and institutions around the world, MIT said.