Astronomers have observed a black hole tearing apart a star far from its galaxy's center, producing the fastest-changing radio signals ever recorded from such an event. Named AT 2024tvd, this tidal disruption event reveals supermassive black holes can exist and remain active in unexpected locations. The discovery, led by an international team, suggests complex, delayed energy releases from black holes.
The event AT 2024tvd marks the first time scientists have witnessed a tidal disruption event (TDE)—where a black hole rips apart a passing star—occurring outside a galaxy's central region. The black hole is located approximately 2,600 light-years (0.8 kiloparsecs) from its host galaxy's center, providing evidence that supermassive black holes can reside in previously overlooked areas.
An international team, led by Dr. Itai Sfaradi and Prof. Raffaella Margutti from the University of California, Berkeley, along with Prof. Assaf Horesh from the Hebrew University of Jerusalem and collaborators worldwide, identified this phenomenon. Observations revealed bright, rapidly evolving radio emission, the fastest ever recorded from a TDE.
"This is truly extraordinary," said Dr. Itai Sfaradi, the study's lead author. "Never before have we seen such bright radio emission from a black hole tearing apart a star, away from a galaxy's center, and evolving this fast. It changes how we think about black holes and their behavior."
Prof. Horesh, Sfaradi's former advisor, added, "This is one of the fascinating discoveries I've been part of. The fact that it was led by my former student, Itai, makes it even more meaningful. It's another scientific achievement that places Israel at the forefront of international astrophysics."
Key observations came from radio telescopes including the Very Large Array (VLA), ALMA, ATA, SMA, and the Arcminute Microkelvin Imager Large Array (AMI-LA) in the UK. The Hebrew University-led AMI data highlighted two distinct radio flares that evolved faster than in any prior TDE. These flares indicate powerful material outflows launched months after the star's destruction, pointing to at least two separate ejection events.
Detailed modeling supports episodic black hole activity, with ejections occurring months apart, suggesting black holes can "reawaken" after inactivity. The findings were published in The Astrophysical Journal Letters (2025; 992 (2): L18). This discovery reshapes understanding of black hole locations and evolution.