The discovery, part of an international observing campaign, marks the first unambiguous detection of a “tidal disruption event” (TDE) caused by an off-centre supermassive black hole.
Tidal disruption events occur when a star drifts too close to a supermassive black hole and is ripped apart by its immense gravitational pull, producing a brilliant burst of energy across the electromagnetic spectrum from visible and X-ray light to radio waves.
The event, dubbed AT 2024tvd, stands out for both its record-breaking speed and unusual location.
“Tidal disruption events are usually found at the hearts of galaxies, whereas AT 2024tvd was caused by an off-centre black hole the first time this has been clearly seen,” said Dr Joe Bright, a radio astronomy researcher at the University of Oxford. “It’s possible that the unprecedented rapid radio evolution is linked to its unusual position in the galaxy.”
The international research team, led by Dr Itai Sfaradi and Dr Raffaella Margutti from the University of California, Berkeley, and including scientists from the SETI Institute, said the finding reshapes how astronomers understand where supermassive black holes can hide.
Most galaxies, including the Milky Way, harbour a supermassive black hole at their core. These cosmic giants influence galaxy formation and evolution, often by launching enormous jets of energy. Yet many remain invisible until a dramatic event like a TDE lights them up.
Radio data from the Allen Telescope Array (ATA) revealed that AT 2024tvd’s host galaxy contains two supermassive black holes: one at its centre and another offset by about 2,600 light years, likely the product of a long-ago galactic merger. When the off-centre black hole shredded an unlucky star, it unleashed two powerful radio bursts, offering a rare glimpse into black hole behaviour beyond galactic nuclei.
“What makes this discovery remarkable is that it reveals a massive black hole that would otherwise be invisible to us,” said Margutti. “We only spotted it because it happened to destroy a star, producing these incredibly bright radio signals.”
SETI Institute researcher Dr Sofia Sheikh said the ATA’s rapid, flexible observations were vital to tracking the event as its radio brightness surged and faded. “Its ability to monitor fast-changing signals across wide frequencies made it uniquely suited to capture the fleeting nature of AT 2024tvd,” she said.
Astronomers said the findings not only shed light on hidden black holes but also reveal new clues about the fate of the obliterated star with models suggesting two energetic outflows, one likely containing remnants of the stellar debris.
The ATA’s role in this breakthrough underscores its growing significance in time-domain astronomy, the study of fast-evolving cosmic events such as TDEs, fast radio bursts and supernovae.