Overview: A rogue black hole and a star’s dramatic fate
Astronomers have recorded a landmark tidal disruption event (TDE) that defies typical expectations: a supermassive black hole shredding a star while sitting far from the heart of its host galaxy. The event, designated AT 2024tvd, produced the brightest and fastest-changing radio signals ever observed from a black hole consuming a star. The discovery challenges preconceived ideas about where black holes live and how they unleash material after a stellar disruption.
The team and the lead researchers
The international collaboration was led by Dr. Itai Sfaradi and Prof. Raffaella Margutti of the University of California, Berkeley, with key contributions from researchers around the world, including Prof. Assaf Horesh of the Racah Institute of Physics at the Hebrew University of Jerusalem. Dr. Sfaradi, a former student of Prof. Horesh, described the finding as a defining moment in his career and for the field at large. Prof. Horesh highlighted the broader significance, noting that Israel’s role in international astrophysics had been reinforced by the research.
A black hole far from home: location matters
In most TDEs, the stellar disruption occurs near the central supermassive black hole of a galaxy. AT 2024tvd, however, occurred roughly 2,600 light-years (about 0.8 kiloparsecs) from the galaxy’s center. This unusual placement shows that supermassive black holes can exist and be active away from galactic cores, broadening the environments where TDEs and associated radio signals may be observed.
The radio observations: why this event is a game changer
The discovery relied on state-of-the-art radio telescopes around the world, including the Very Large Array (VLA), ALMA, the Atacama Large Millimeter/submillimeter Array, the Submillimeter Array (SMA), the Allen Telescope Array (ATA), and the Arcminute Microkelvin Imager Large Array (AMI-LA) in the United Kingdom. The AMI observations, led by the Hebrew University team, were especially pivotal in capturing the rapid evolution of the radio emission—the fastest changes ever seen in a TDE radio flare.
Data revealed two distinct radio flares that evolved more quickly than any previously documented TDE. The observations imply powerful outflows were launched from the black hole’s vicinity not immediately after the stellar disruption, but months later. This points to delayed, complex processes shaping the aftermath of a disruption and indicates that black holes can undergo episodic “reawakening.”
What the findings mean for black hole physics
Modeling of AT 2024tvd supports the scenario of at least two separate ejection events, suggesting a more dynamic and less predictable response of black holes to stellar infall. The rapid radio evolution and dual flares provide fresh clues about how matter is accelerated and expelled at relativistic speeds, as well as how magnetic fields may organize and reconfigure over time in the aftermath of a tidal disruption.
Experts emphasize that the event expands the known diversity of TDEs and radio-bright black holes. It also underscores the critical role of long-baseline radio monitoring in catching late-stage or episodic activity that optical surveys might miss.
Collaborations and publication
The study is the product of a wide collaboration spanning the United States, Europe, and Israel, with contributions from institutions including the Open University of Israel (Prof. Paz Beniamini) and many others. The findings were published in The Astrophysical Journal Letters, reflecting a growing global effort to map how black holes interact with their environments across vast cosmic distances.
Looking ahead
AT 2024tvd demonstrates that black holes can exhibit surprising behavior far from galactic centers and can experience episodic reactivation long after a disruption. As radio astronomy continues to advance, researchers expect more TDEs with unusual locations and rapid radio variability, which will help refine models of black-hole physics and improve our understanding of how these enigmatic objects shape their host galaxies.
