Astronomers have been left stunned after spotting a black hole 'burping' out material three years after it devoured a star.
The rare cosmic event took place 665 million light years away, creating a bright display visible from space telescopes on Earth.
A more routine burst of activity had previously been picked up in 2018, when the black hole was seen swallowing up a smaller star and tearing it into small pieces in a Tidal Disruption Event (TDE) named AT2018hyz.
The original outflow created a bright reaction of the kind occasionally seen by scientists at Very Large Array Radio Telescope facility in New Mexico - but a return inspection of the TDE turned up some more unusual results.
Radio data from the space telescope showed it had unexpectedly reanimated in June 2021, causing the shocked research team to quickly refocus their attention on the event.
Outflows usually emerge quickly after a TDE, and are not known to take place years later.
The 'burps' of material coming from this rare activity appeared to be going faster than would normally be expected, travelling at half the speed of light compared with the usual 10 percent, physicists revealed.
It is also thought to be one of the brightest TDES ever recorded.
Commenting on how the scientists responded to the unusual black hole activity, Yvette Cendes, research associate at the Harvard & Smithsonian's Centre for Astrophysics said: “This caught us completely by surprise — no one has ever seen anything like this before,”
“We applied for Director’s Discretionary Time on multiple telescopes, which is when you find something so unexpected, you can’t wait for the normal cycle of telescope proposals to observe it”
“All the applications were immediately accepted.”
She added that the "next step" following the exciting discovery would be to explore whether the phenomenon happens more regularly, which if so would suggest astronomers have "simply not been looking at TDEs late enough in their evolution".
Edo Berger, co-author and professor of astronomy, concluded: "We have been studying TDEs with radio telescopes for more than a decade, and we sometimes find they shine in radio waves as they spew out material while the star is first being consumed by the black hole.
"But in AT2018hyz there was radio silence for the first three years, and now it's dramatically lit up to become one of the most radio-luminous TDEs ever observed."
