JWST Finds Three Feeding Black Holes in One Early Galaxy, Two Set to Merge

Start with a distance: 620 light-years. That is how far apart, as seen on the sky, two supermassive black holes sit near the center of a galaxy called J0148-4214. At that spacing, even the James Webb Space Telescope cannot show them as separate points of light. Astronomers inferred them from the structure of the light, and they expect the pair to merge within the next few hundred million years, according to the Max Planck Society.

The galaxy lies more than 12.5 billion light-years away, at a redshift of 5.02. Webb sees it as it was about 1.2 billion years after the Big Bang, when the universe was less than a tenth of its present age. In all, the team found three actively feeding black holes in it. Their estimated masses are about 80 million, 2 million, and 600,000 times the mass of the Sun. The two central ones are the close pair. The third sits roughly 5,500 light-years from the center.

The study appears in Astronomy & Astrophysics. It is not breaking news: the findings were first released as a preprint in September 2025, and the Max Planck Society announced them in August 2026. A ScienceDaily summary on Oct. 25 brought fresh attention. Lead author Hannah Übler of the Max Planck Institute for Extraterrestrial Physics called it the first evidence of three active black holes in a single galaxy in the distant universe. The galaxy's stars total about 1.3 billion solar masses, which means the black holes make up an unusually large share of its mass. Where the third black hole came from is unclear. It could be left over from an earlier galaxy merger, kicked outward by a recoil when two black holes combined, or slowly drifting inward.

The smallest of the three, at about 600,000 solar masses, is feeding faster than the Eddington limit. That limit is the maximum rate at which basic theory says a black hole can swallow gas, since radiation from infalling material pushes back on new gas. The most massive black hole in the galaxy is feeding at a lower rate. Bursts of super-Eddington feeding are one proposed explanation for a puzzle Webb keeps raising: black holes that reached millions or billions of solar masses very early in cosmic history, faster than standard models easily allow.

Co-author Roberto Maiolino of the University of Cambridge said the results suggest mergers may be another fast route to that growth. When the central pair combines, their mass joins in one step, on top of steady feeding.

Separating the pair took a technique called spectro-astrometry. The team used Webb's NIRSpec integral field spectrograph, which records a spectrum at every point across the galaxy, as part of a program called BlackTHUNDER that studies black holes in early galaxies. Gas whirling around each black hole moves fast and leaves a distinctive signature in hydrogen light. By measuring tiny positional shifts in that light at different velocities, the researchers showed the signal came from two slightly offset sources rather than one. They said that without this spatially resolved spectroscopy, probably only one of the three black holes would have been detected.

That raises a wider question. If close pairs routinely masquerade as single objects, surveys may be undercounting multiple black holes in early galaxies, and reanalyzing existing Webb data with the same method could turn up more pairs and triples.

The limits are worth stating. This is a peer-reviewed observational study of a single galaxy, so it cannot say how common such systems are. The central pair was inferred from spectral structure the authors say is best explained by two black holes. Masses and feeding rates are estimates, and the merger timeline is a projection from the estimated separation, not a measured orbit. The "first" claim comes from the research team and has not been independently tested. Giovanni Mazzolari and other co-authors at the Max Planck Institute for Extraterrestrial Physics derived the stellar mass from the same Webb data.

Nothing here touches life on Earth. The payoff is better models of how black holes and galaxies grew together. Future gravitational wave observatories, such as the planned LISA mission, are designed to detect massive black hole mergers and could test whether they were common early on, while more Webb spectroscopy should show whether triples like this one are rare or routine.