Astronomers Astonished by Largest Explosion Since the Big Bang

Yahoo

11 hours ago

You've heard of how mighty supernovas are, or of the ungodly amounts of energy released by gamma ray bursts.
But astronomers have just discovered a type of cosmic blast that puts all those to shame. They're called "extreme nuclear transients" (ENTs) — and they're quite literally the most powerful explosion witnessed since the dawn of time.
What produces ENTs is appropriately catastrophic: a star, at least three times as massive as our Sun, being obliterated by a supermassive black hole.
"We've observed stars getting ripped apart as tidal disruption events for over a decade, but these ENTs are different beasts, reaching brightnesses nearly ten times greater than what we typically see," Jason Hinkle, lead author of a new study published in the journal Science Advances, and a researcher at the University of Hawai'i's Institute for Astronomy (IfA), said in a statement about the work.
"Not only are ENTs far brighter than normal tidal disruption events, but they remain luminous for years, far surpassing the energy output of even the brightest known supernova explosions," Hinkle added.
The first clues emerged when Hinkle and his team were trawling through public data collected by the European Space Agency's Gaia mission, a vast three-dimensional map of over two billion stars and counting. Amid this stellar sea, they noticed flares of light, including one recorded in 2016 and another in 2018, that inexplicably lasted for several years. Most cosmic explosions, for comparison, only shine for several weeks.
"When I saw these smooth, long-lived flares from the centers of distant galaxies, I knew we were looking at something unusual," Hinkle said.
He wasn't the only one on the scent. Back in 2023, another team of astronomers reported a similar detection with the Zwicky Transient Facility in California. Following-up on these findings, Hinkle conducted additional observations with other telescopes, including the Keck Observatory in Hawaii, and linked these phenomena together.
The most formidable ENT, assigned the screenname-esque moniker of Gaia18cdj, unleashed 25 times more energy than the most powerful supernova ever detected. In one year, it radiated energy equal to all the energy our Sun will produce in its entire lifetime across billions of years — times one hundred. Typically, a supernova produces "just" one Sun's worth of energy.
To produce such a tremendous blast, a star has to undergo a brutal, slow death. That's what sets these apart from when a star falls into a black hole in a typical tidal disruption event, which culminates in a powerful but brief flash. An ENT draws out the torture, forming a disk of the star's shredded entrails that glows for years.
This aspect of a supermassive black hole's diet could tell us a lot about how they grew to their monstrous masses — a mystery that has long haunted astronomers — and how they stamped their name on a crucial period of the universe's history.
"By observing these prolonged flares, we gain insights into black hole growth when the universe was half its current age and galaxies were busy places — forming stars and feeding their supermassive black holes ten times more vigorously than they do today," said coauthor Benjamin Shappee, an associate professor at IfA, in a statement.
"These ENTs don't just mark the dramatic end of a massive star's life. They illuminate the processes responsible for growing the largest black holes in the universe," Hinkle added.
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