Rare cosmic explosion brighter than billions of suns spotted in red galaxy
Astronomers have discovered a new type of cosmic explosion which outshines nearly every supernova detected in the universe.
As bright as hundreds of billions of suns, but quick to fade – the rare and dazzling blast is believed to have been caused by a black hole colliding with a star and was spotted by researchers at Queen’s University Belfast.
They first identified the event, known as AT2022aedm, using the Atlas network of robotic telescopes in Hawaii, Chile and South Africa.
They scan the sky every night to search for any object that moves or changes in brightness.
Researchers delved deeper into the blast with the New Technology Telescope in Chile and found that it looked unlike any known supernova and lasted less than half as long.
The team has been hunting for the most powerful cosmic explosions for over a decade.
Dr Matt Nicholl, from the School of Mathematics and Physics at Queen’s, described the discovery as “one of the brightest we’ve ever seen”.
He said: “Usually, with a very luminous supernova, it will have faded to maybe half of its peak brightness within a month. In the same amount of time, AT2022aedm faded to less than one per cent of its peak – it basically disappeared.”
Where the explosion occurred also came as a surprise to the team.
Dr Shubham Srivastav, also from Queen’s, said: “Our data showed that this event happened in a massive, red galaxy two billion light years away. These galaxies contain billions of stars like our sun, but they shouldn’t have any stars big enough to end up as a supernova.”
Historical data showed there have been just two other cosmic events with a similar set of properties – discovered by the ROTSE and ZTF surveys in 2009 and 2020.
Dr Nicholl added: “We have named this new class of sources ‘Luminous Fast Coolers’, or LFCs. This is partly to do with how bright they are and how fast they fade and cool.
“But it’s also partly because myself and some of the other researchers are huge fans of Liverpool Football Club. It’s a nice coincidence that our LFCs seem to prefer red galaxies.”
Dr Nicholl added the discovery has opened up avenues for more research.
“The exquisite data set that we have obtained rules out this being another supernova. The most plausible explanation seems to be a black hole colliding with a star,” he said.
“If we find more LFCs, especially in the more local universe, we should be able to test this scenario. Collisions are more likely in dense star clusters, so we can look for these at the sites of the explosions.”
The research paper has been published in The Astrophysical Journal Letters.