Astronomers have witnessed a supermassive black hole eating gas from a nearby galaxy and then "burping" - twice.
The University of Colorado at Boulder team found that a black hole they were studying had essentially let off jets of bright light from the gas it consumed twice over the course of 100,000 years.
Assistant professor Julie Comerford, who led the study, said that while astronomers have predicted that black holes could burp out light as a result of gas-feeding events, this is one of the few times one has been caught in the act.
"We are seeing this object feast, burp and nap, and then feast, burp and nap once again, which theory had predicted," Ms Comerford said.
"Fortunately, we happened to observe this galaxy in a moment where we could clearly see both events."
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Supermassive black holes are millions of times heavier than the sun and are believed to be at the heart of virtually every galaxy.
Just like normal black holes, they are regions of space-time with gravitational effects so strong that even electromagnetic radiation such as light cannot escape from inside of them.
With supermassive black holes, the gas that they accrete in space generates a lot of electromagnetic radiation as it becomes increasingly dense and is pulled towards the event horizon.
This energy is released in quasars which erupt right across the electromagnetic spectrum, from radio waves through to visible light and X-ray wavelengths.
The team was able to detect a "remnant emission" south of the centre of the galaxy which indicated there had been a black hole feasting event, while another loop of gas north of the galaxy signalled a more recent burp.
"This galaxy really caught us off guard," said Rebecca Nevin, a study co-author and doctoral student at CU Boulder.
"We were able to show that the gas from the north part of the galaxy was consistent with an advancing edge of a shock wave, and the gas from the south was consistent with an older quasar outflow."
Our own galaxy, the Milky Way, has experienced at least one burp, Ms Comerford added - noting how "Fermi bubbles" had been detected shining at the extreme end of the electromagnetic spectrum.
"These are the kinds of bubbles we see after a black hole feeding event," she said.