An explosion in space nicknamed the Tasmanian devil has confused astronomers by flashing at peak brightness more than a dozen times, months after the initial event. The observation, while posing new questions, could help to narrow down what might cause such explosions, which are known as luminous fast blue optical transients (LFBOTs).
LFBOTs are seen across the Universe and defy explanation. The first, dubbed the Cow after its designation AT2018cow, was spotted in 2018 in a galaxy about 60 million parsecs (200 million light years) from Earth. The Cow was notable for being up to 100 times brighter than a supernova before dimming over just a few days, a process that takes weeks for a supernova.
More than half a dozen LFBOTs have since been found, including ones referred to as the Koala, the Camel and, earlier this year, the Finch. But astronomers are still not sure what is causing them. The leading ideas are that these explosions are either failed supernovae — stars collapsing into a black hole or neutron star before they can explode — intermediate-mass black holes consuming other stars, or the results of objects interacting with hot, bright stars known as Wolf-Rayet stars.
In a study published on 15 November in Nature, a team led by astronomer Anna Ho at Cornell University in Ithaca, New York, describes new activity from an LFBOT that had been discovered about 1 billion parsecs away in September 2022; this one, formally called AT2022tsd, is known as the Tasmanian devil. Initially using the Magellan-Baade telescope in Chile, the researchers found that the Tasmanian devil repeatedly flashed at its peak brightness, starting in December 2022. They saw 14 of these flaring events in total, each lasting only minutes.
“Flashes like this haven’t been seen before in LFBOTs,” says Ho. She adds that each of the unexpected flares was “as powerful as the original LFBOT.”
“It’s an amazing observation,” says Raffaella Margutti, an astrophysicist at the University of California, Berkeley. “This is unprecedented. It opens a lot of questions.”
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