Astronomers have discovered three actively feeding supermassive black holes in a single galaxy more than 12.5 billion light-years from Earth. The finding, made by an international research team led by the Max Planck Institute for Extraterrestrial Physics (MPE), offers a rare glimpse of how enormous black holes grew and interacted during the universe’s earliest stages.
The black holes are located in a galaxy known as J0148-4214. All three are actively accumulating matter, which spirals toward them through surrounding disks of gas and other material. Because the galaxy is so distant, its light has traveled through space for approximately 12.5 billion years before reaching Earth. This means astronomers are observing it as it existed just 1.2 billion years after the Big Bang.
Over such vast distances, the expansion of the universe stretches light to longer, redder wavelengths. Astronomers measure this effect through a property called redshift. For J0148-4214, the researchers measured a redshift of z=5.02, allowing them to determine its remarkable distance.
Three Black Holes in One Ancient Galaxy
“This is the first evidence of three active black holes in a single galaxy in the distant Universe,” says Hannah Übler, research group leader at MPE and lead author of the study.
Two of the black holes lie near the galaxy’s center, separated by a projected distance of just 620 light-years. The third is much farther out, approximately 5,500 light-years from the center.
The discovery provides important evidence about how massive black holes came together in the young universe.
“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,” says Übler.
Astronomers believe that galaxy collisions and mergers were common during the universe’s early history. As galaxies combined, their central black holes could also move closer together and eventually merge. These mergers would produce increasingly massive black holes at the centers of the newly formed galaxies, potentially helping explain how some grew to enormous sizes so soon after the Big Bang.
How Astronomers Detected the Hidden Black Holes
The researchers identified the three black holes by examining distinctive patterns in the light emitted by hydrogen gas. Near a black hole, powerful gravitational forces cause gas to move at extremely high speeds. These movements leave recognizable signatures in the spectrum of light, allowing astronomers to detect black hole activity even when the objects themselves cannot be seen directly.
In the center of J0148-4214, the team found a particularly complicated hydrogen emission pattern. The best explanation was the presence of two closely spaced black holes rather than a single source.
To distinguish between them, the scientists used a precise measurement technique called spectro-astrometry. By tracking subtle changes in the positions of spectral emissions across the galaxy, they were able to identify the locations of both central black holes, even though the telescope could not resolve them as two separate points of light.
The observations also revealed the third active black hole in the galaxy’s outer region.
Three Black Holes With Remarkably Different Masses
The three black holes vary dramatically in size. According to the researchers’ calculations, their masses are approximately 80 million, 600,000, and 2 million times that of the Sun.
Surprisingly, the largest black hole is not the one feeding most aggressively. Its smaller neighbor, with a mass of roughly 600,000 suns, is accumulating matter at a much higher rate. In fact, its estimated feeding rate exceeds the maximum predicted by basic models of black hole growth (the Eddington limit).
This unusually rapid growth may offer clues to how some black holes became extraordinarily massive during the relatively short time available in the early universe.
“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,” says Dr. Giovanni Mazzolari, second author of the study and researcher at MPE. “We find a total stellar mass of about 1.3 billion suns, and the black holes represent a significant fraction of that.”
An Ancient Black Hole Merger in the Making
The two black holes near the galaxy’s center are expected to merge within the next few hundred million years. Their eventual collision could help produce an even more massive black hole, illustrating a process that may have been essential to the growth of the universe’s earliest cosmic giants.
“These results are extremely exciting,” adds Roberto Maiolino, professor at the University of Cambridge and co-author of the study. “They suggest that black hole merging may be an additional, fast route for their rapid growth in the early Universe.”
The third black hole presents another intriguing puzzle. Located well outside the galaxy’s center, it could be a remnant of an earlier merger that was pushed outward by a powerful gravitational recoil. Such a kick can occur when merging black holes emit gravitational waves unevenly, sending the resulting black hole in the opposite direction.
Another possibility is that the third black hole is gradually moving toward the galaxy’s center, where it may eventually interact with the other two.
James Webb Reveals Black Holes That Might Otherwise Remain Hidden
The discovery highlights the remarkable capabilities of the James Webb Space Telescope (JWST) for studying black holes in distant galaxies.
In particular, the findings demonstrate the importance of integral field spectroscopy, which allows astronomers to examine how light and its spectral signatures vary across different parts of a galaxy.
Using Webb’s Near Infrared Spectrograph in its integral field spectroscopy mode (NIRSpec-IFS), the researchers were able to separate signals that would otherwise have appeared to come from a single black hole.
Without that detailed spatial information, astronomers likely would have identified only one of the galaxy’s three active black holes.
The results suggest that other distant galaxies may contain multiple growing black holes that have gone undetected. Finding more of these hidden systems could help scientists reconstruct the history of black hole mergers and better understand how the universe produced its most massive black holes so early in cosmic history.
