NASA's Swift detects wandering black hole shredding star far from galaxy core

NASA's Neil Gehrels Swift Observatory has detected a supermassive black hole shredding a star on the outskirts of a galaxy, marking the first time such an event has been observed so far from a galactic core. The black hole, weighing about a million times the mass of the Sun, was found in the galaxy WISEA J014656.04-152214.7, located roughly 750 million light-years away in the constellation Cetus. The discovery was first flagged in November 2025 by the Zwicky Transient Facility (ZTF) at Palomar Observatory in Southern California, which spotted an unusual brightening. An artificial intelligence algorithm identified the flare as a likely tidal disruption event, where a star is torn apart by a black hole's gravity. For several months, the event outshone its entire host galaxy in ultraviolet light, temporarily radiating with the brightness of about 10 billion suns.

This finding affects our understanding of where supermassive black holes can exist. Typically, these black holes reside at the centers of galaxies, and tidal disruption events have only been seen in galactic cores until 2024, when one was spotted 2,600 light-years from its galaxy's center. The new event is more than 30,000 light-years from its galaxy's center, suggesting that black holes can wander far from their original locations. The discovery matters because it validates a new technique for finding otherwise invisible wandering black holes, which could help astronomers determine how common such objects are.

Follow-up observations were conducted by the SOAR telescope in Chile and NASA's Swift observatory. Swift's Ultraviolet/Optical Telescope measured the temperature of the flare at about 54,000 degrees Fahrenheit (30,000 degrees Celsius). The combination of data ruled out other explanations, confirming the event as a tidal disruption event despite its unusual location. The research, led by Robert Stein of the University of Maryland and NASA's Goddard Space Flight Center, was published on Monday in The Astrophysical Journal Letters.

Background: Nearly every galaxy has a supermassive black hole at its center, and tidal disruption events occur roughly once every 100,000 years per galaxy. Astronomical surveys typically spot about 30 such events each year across the universe. Prior to 2024, all were seen in galaxy cores because that's where astronomers looked. The new event's origin is unclear; researchers propose two possibilities: either three or more galaxies merged, and gravitational interactions flung the black hole to the edge, or a dwarf galaxy is merging with the larger one, and a star passed too close to the dwarf's black hole. The next steps involve further discoveries to answer the key question: How common are wandering black holes?