NASA’s Neil Gehrels Swift Observatory has observed a rare supermassive black hole tearing apart and consuming stars far from the center of a distant galaxy. Astronomers describe the star as an apparent “orphan” because it is unusually far away from the center of galaxies, where supermassive black holes are normally found. This type of phenomenon has never before been detected this far from the center of a galaxy.
“We were looking for these star-shattering events as a way to find invisible supermassive black holes that wander far from the centers of galaxies where they normally reside,” said Robert Stein, a research scientist at the University of Maryland, College Park, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This discovery is one of only two confirmed to date, validating a new technique that can now be used for further exploration.”
A paper led by Stein describing the results was published in the journal July 27. Astrophysics Journal Letter.
A star shattered by a hidden black hole
The discovery began with an extremely bright flare produced when a star flies too close to a supermassive black hole and is torn apart by its strong gravity. Astronomers call this type of phenomenon tidal disruption.
The mass of the black hole responsible is about 1 million times that of the sun. Its existence was first suspected in November 2025, when the ZTF (Zwicky Transitional Facility), a sky survey run by Southern California’s Palomar Observatory, detected an unusual burst of light in a galaxy some 750 million light-years from Earth.
“Of the 500,000 flashes that ZTF detects each night, our new artificial intelligence algorithm automatically recognized a flare that closely resembles a tidal disruption event, despite its unusual location on the outskirts of the galaxy,” Stein said.
For several months, this flare was brighter in ultraviolet light than the entire surrounding galaxy. At its peak, it briefly emitted as much light as about 10 billion suns.
Swift confirms extreme space flare
After the initial ZTF detection, additional observatories examined the source. The SOAR (Southern Astrophysical Research) telescope in Chile studied its spectrum and found features consistent with tidal disruption phenomena.
So astronomers turned to NASA’s Swift Observatory, which can probe wavelengths that ground-based telescopes can’t detect. For example, Swift’s UVOT (Ultraviolet/Optical Telescope) measured the temperature of the flare at approximately 54,000 degrees Fahrenheit (30,000 degrees Celsius).
“By combining all of this data, we can now rule out other explanations and say with confidence that this is a tidal disruption event, despite its strange location,” said Jonathan Carney, a doctoral student at the University of North Carolina at Chapel Hill.
Hidden heroes at the center of the galaxy
Almost every galaxy in the universe appears to have a supermassive black hole at its center. Approximately once every 100,000 years, a star in a given galaxy comes close enough to one of these black holes that a tidal disturbance can tear it apart.
Although it is extremely rare for such events to occur within individual galaxies, astronomers monitor millions of galaxies to find them. Current research typically detects about 30 tidal disruption events each year across the universe.
Before 2024, all confirmed examples were found at the center of galaxies. One reason for this was that all known supermassive black holes were located at the center of galaxies, so astronomers focused their searches there. A tidal disruption event also requires a very massive black hole, since the gravity of a light black hole is not strong enough.
This assumption began to change when scientists detected signs of star destruction 2,600 light-years from the center of the host galaxy. This discovery prompted astronomers to expand their search beyond the galactic core.
The newly confirmed cases are even more extreme. It occurred more than 30,000 light years from the center of the galaxy.
How did the black hole get there?
The black hole’s unusual location raises big questions about its past.
“It must have originated in the center of the galaxy, not in today’s suburbs,” Stein said. “We think the host galaxy’s supermassive black hole is still at its center, but this star-eating black hole may have started as a smaller galaxy that merged with the larger galaxy we see today.”
The researchers have proposed two possible explanations.
In one scenario, three or more galaxies merged. The supermassive black holes at their centers could then become trapped in a gravitational struggle, and the lightest black holes could be launched towards the edge of the merging galaxy.
Another possibility is that the dwarf galaxy is still in the process of merging with a larger system. As stars from the dwarf galaxy enter the larger galaxy, one of them may have gotten too close to the dwarf galaxy’s supermassive black hole.
“Further discoveries may reveal the origin of this apparently ‘orphan’ black hole,” Stein said. “The key scientific question we want to answer is how common are wandering black holes?”
Swift is waiting for Orbit Boost
Astronomers may soon be able to answer that question by discovering more displaced black holes.
“Advanced science observations with Swift’s UVOT and XRT (X-ray telescope) instruments will be temporarily suspended pending an orbital boost scheduled for this summer,” said co-author S. Bradley Senko, Swift Principal Investigator at NASA Goddard.
Swift’s main mission lasted from 2004 to 2006, but the spacecraft continued to observe the changing universe for more than two decades. Currently, it is gradually approaching Earth due to atmospheric resistance. Raising Swift to a higher orbit could keep it running even longer.
“Once it resumes normal operation, Swift may continue to look for more examples of out-of-place black holes.”
A new exploration of a wandering black hole
In the coming years, astronomers will apply the same detection techniques to observations from the newly operational Vera C. Rubin Observatory, jointly funded by the U.S. Department of Energy and the National Science Foundation in Chile, and NASA’s upcoming Nancy Grace Roman Space Telescope.
“Rubin’s wide-ranging and deep survey will reveal a much larger sample of tidal disruption events than current observatories can collect, including off-center ones,” Carney said. “And Roman’s space-based survey will extend the scope of current research by looking back over 9 billion years of cosmic history and seeing what lies further afield.”
By combining data from Rubin, Roman, Swift, and ground-based observatories, scientists may be able to identify even more wandering black holes. These discoveries could ultimately help astronomers build the most complete census of the universe’s supermassive black holes to date.
