For the first time, scientists have observed a tidal disruption event (TDE) — a phenomenon in which a passing black hole grabs a star — outside the central region of the galaxy. The extraordinary discovery revealed powerful and rapidly changing radio waves, indicating that supermassive black holes may exist and be more active than galactic centers. The delayed, intense radio bursts also point to a previously unknown mechanism for how black holes release material over extended periods.
An international team led by Dr. Attai Safadi and Professor Raffaella Margotti of the University of California, Berkeley, together with colleagues from around the world, including Asif Horesh, Professor of Physics at the Hebrew University of Jerusalem, identified the first TDE to produce bright radio signals far from the center of a galaxy.
The event, dubbed 2024 TVD, showcased the fastest-changing radio emission ever recorded from a black hole.
“It’s really unusual,” said Dr. Attai Safadi, lead author of the study. “Never before have we seen such bright radio emission from a black hole that rips apart a star, away from the center of a galaxy, and evolves this rapidly. This changes how we think about black holes and their behavior.”
Dr. Safadi, a former student of Professor Horesh, led the research. “This is one of the most exciting discoveries I’ve been a part of,” Professor Horisch said. “The fact that it was led by my former student, Atai, makes it even more meaningful. This is another scientific achievement that puts Israel at the forefront of international astrophysics.”
A black hole far from home
A tidal disruption event occurs when a star is too close to a massive black hole and is pulled apart by its immense gravitational forces.
In this rare instance, the black hole was found about 2,600 light-years (0.8 kiloparsi) from the center of its host galaxy—strong evidence that supermassive black holes can exist in surprising and previously overlooked places.
Key role of radio observations
The discovery was made possible by high-quality observations from a number of the world’s premier radio telescopes in the UK, including the Very Large Array (VLA), ALMA, ATA, SMA, and the Arcanet Microwave Imager Large Array (AMI-LA).
The AMI observations, led by a team from the Hebrew University, were crucial in revealing the unusually fast evolution of the radio emission – a hallmark of the event and an important clue to understanding its physical nature.
The data show that two separate radio flares develop faster than any TDE before. These results show that the powerful outflow of material from the vicinity of the black hole immediately after the stellar destruction. Not later, but months later, disruptions resulted in delays and complicated process proposals.
Detailed modeling points to at least two separate ejection events, months apart—clear evidence that black holes can be decently “reawakened” after periods of apparent inactivity.
The research was carried out in collaboration with scientists from institutions in the United States, Europe and Israel, including Prof. Paz Benemini of the Open University of Israel, and was published in Astronomical Journal Letters.
