The Big Bang's being given a run for its money with the discovery of an interstellar explosion so huge astronomers are at a loss as to what caused it.
A distant supermassive black hole let off so much energy, it left a hole in the gas around it big enough to fit 15 Milky Way galaxies end-to-end - 1.6 million lightyears across.
"We've seen outbursts in the centres of galaxies before but this one is really, really massive," said Melanie Johnston-Hollitt of Curtin University in Australia.
The monster boom took place hundreds of millions of years ago in the Ophiuchus galaxy cluster, about 390 million lightyears from Earth, researchers said in a new study, published in The Astrophysical Journal on Friday.
"We don't know why it's so big," added Dr Johnston-Hollitt, who used to be based at Victoria University of Wellington.
The hole had been seen before in X-rays, but no one believed it could have come from a single event. But after analysing it with radio telescopes, the astronomers said the evidence fit "like a hand in a glove".
"People were sceptical because of the size of outburst," said Dr Johnston-Hollitt. "But it really is that. The universe is a weird place."
This bang is five times bigger than the previous record-holder - not including the big one scientists believe marked the start of the universe itself. But they don't expect Ophiuchus to hold the record forever, with the technology only getting better.
This boom was analysed using arrays of telescopes across the world, including the Murchison Widefield Array in Western Australia (MWA).
"We made this discovery with Phase 1 of the MWA, when the telescope had 2048 antennas pointed towards the sky," said Dr Johnston-Hollitt.
"We're soon going to be gathering observations with 4096 antennas, which should be 10 times more sensitive. I think that's pretty exciting."
