Astronomers have found three black holes in one galaxy in the early universe, all of them actively feeding, in a system seen as it was about 1.2 billion years after the Big Bang. The galaxy, J0148-4214, lies more than 12.5 billion light-years away. The discovery was made by an international team led by the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, using the James Webb Space Telescope.
The study, titled “BlackTHUNDER: Evidence of three massive black holes in a z ~ 5 galaxy,” was published in the journal Astronomy & Astrophysics and announced by the Max Planck Society in August. It drew fresh attention this weekend after ScienceDaily featured the findings on Oct. 25, 2026.
What Astronomers Found in Galaxy J0148-4214
The galaxy’s light is stretched toward redder wavelengths by the expansion of the universe, a measure called redshift. The researchers measured a redshift of z = 5.02 (5.0167 in the paper), which places it in the first tenth of cosmic history.
Two of the black holes sit near the galaxy’s core, separated by a projected distance of about 620 light-years, or roughly 190 parsecs. The third lies in the outskirts, about 5,500 light-years (1.7 kiloparsecs) from the center.
“This is the first evidence of three active black holes in a single galaxy in the distant Universe,” said Hannah Übler, a research group leader at MPE and the study’s lead author. “It suggests that processes in the early Universe were efficient at bringing massive black holes together, setting the stage for the massive black hole mergers we expect to detect with future gravitational wave observatories.”
Three Very Different Masses, One Fast Eater
The team estimated the black holes’ masses at about 80 million, 600,000 and 2 million times the mass of the Sun. In the paper’s notation, that is log masses of 7.9, 5.8 and 6.3, each with an uncertainty of roughly half a dex.
The heaviest one is not the hungriest. Its 600,000-solar-mass neighbor near the center is pulling in matter faster, at a rate that exceeds the Eddington limit, the ceiling predicted by basic models of how fast a black hole can grow before the radiation it produces pushes incoming gas away.
“The JWST data allowed us not only to identify the three black holes, but also to estimate their masses, accretion rates, and the stellar mass of the galaxy,” said Giovanni Mazzolari, the paper’s second author and an MPE researcher. “We find a total stellar mass of about 1.3 billion suns, and the black holes represent a significant fraction of that.” For comparison, the Milky Way’s central black hole, Sagittarius A*, is about 4 million solar masses inside a galaxy far larger in stars.
How the James Webb Space Telescope Spotted Them
None of the black holes can be seen directly. The team found them through the light of hydrogen gas whirling around each one at high speed, which produces broad emission lines in the galaxy’s spectrum. The paper reports broad hydrogen-alpha emission with widths from about 430 to 2,920 kilometers per second.
The data came from the Near Infrared Spectrograph on the James Webb Space Telescope, used in its integral field mode, which records a separate spectrum for each small patch of the galaxy. In the core, the hydrogen signal had an uneven, complex shape that the researchers concluded was best explained by two black holes close together. To separate them, they used spectro-astrometry, a technique that tracks tiny shifts in where emission comes from across the image, even when two sources blur into one point.
According to MPE, without that spatially resolved data, astronomers would probably have detected only one of the three. The authors write that this suggests systems with multiple massive black holes were likely common in the early universe and may be hiding in other distant galaxies.
A Black Hole Merger in the Making
The central pair is expected to merge. The paper’s simple dynamical friction estimate puts that at roughly 700 million years or less, which MPE describes as “the next few hundred million years.” If the outer black hole is also sinking inward, a second merger could follow.
“They suggest that black hole merging may be an additional, fast route for their rapid growth in the early Universe,” said Roberto Maiolino, a University of Cambridge professor and co-author.
The outer black hole has another possible explanation: it could be the leftover of an earlier merger, kicked away from the center by a gravitational recoil. That kind of kick can happen when two merging black holes emit gravitational waves unevenly and the combined black hole is pushed in the opposite direction.
Mergers like these are a key target for LISA, the Laser Interferometer Space Antenna. The European Space Agency formally adopted the mission in January 2024 and plans to launch it in 2035. The authors examined how likely LISA would be to detect mergers from systems like J0148-4214.
The finding adds to a busy season in astronomy. Earlier this month, researchers reported the first known green star, a rare white dwarf, and the 2026 Nobel Prize in Physics honored IceCube’s Francis Halzen. Japan also launched its MMX mission to return samples from Mars’ moon Phobos.
Sources
- Max Planck Society: Three supermassive black holes discovered in a single galaxy for the first time
- Astronomy & Astrophysics: BlackTHUNDER: Evidence of three massive black holes in a z ~ 5 galaxy (Übler et al.)
- ScienceDaily: Three giant black holes discovered in a galaxy from the dawn of time
- ESA: Capturing the ripples of spacetime, LISA gets go-ahead
- NASA: James Webb Space Telescope mission
- NASA Science: Black holes
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