Researchers have identified the most distant dormant black hole known, dating back to the universe’s early history.
Astronomers have long relied on brilliant quasars, supermassive black holes actively feeding on surrounding matter, to study the early universe. Yet these luminous objects reveal only part of the story. Now, researchers have detected the most distant dormant black hole ever found, offering a rare look at a giant cosmic object that has gone quiet.
The international team, including scientists from UCL, identified the black hole in the galaxy MRG-M0138, located more than 10 billion light-years from Earth. The discovery, published in Science, shatters the previous distance record for a dormant black hole by a factor of 15.
With a mass roughly 6 billion times that of the Sun, the black hole is being observed at a time when the universe was just 3 billion years old. Its existence provides an unprecedented opportunity to investigate how massive black holes and their host galaxies evolved during the universe’s formative years.
To determine its mass, researchers used observations from NASA’s James Webb Space Telescope (JWST) to track the movements of stars orbiting the otherwise invisible object. Although this method, known as stellar dynamics, has been used to measure dormant black holes in much closer galaxies, this is the first time it has been successfully applied at such a vast (cosmological) distance.
Senior Author, Professor Richard Ellis (UCL Physics & Astronomy) said: “Determining how stars collectively move within the core of this distant galaxy has allowed us to measure the mass of its otherwise undetectable supermassive black hole. By demonstrating the feasibility of such a technique for galaxies in the early universe, we can now undertake a more complete census of how black holes develop over time and infer their role in shaping galaxy evolution.”
How Astronomers Weighed an Invisible Black Hole
Black holes do not emit light themselves, but gas falling into them can release enormous amounts of radiation. These bright objects, known as active galactic nuclei or quasars, are among the most luminous phenomena in the universe and are relatively easy to spot.
The supermassive black hole in MRG-M0138, however, is inactive. Because no gas is currently falling into it, astronomers could detect it only through its gravitational influence on nearby stars.
By measuring the combined motions of stars orbiting the galaxy’s center, the team was able to confirm the black hole’s presence and calculate its mass. Differences in the speeds of stars near the black hole compared with those farther away provided the data needed for the measurement.
This approach is similar to methods used to determine the mass of the black hole at the center of our own galaxy, the Milky Way, as well as those in several nearby galaxies. However, this is the first time it has been applied to an object at such an extreme distance. Previously, the farthest galaxy studied using this technique was about 700 million light-years away.
Gravitational Lensing Enables Historic Measurement
Normally, observing stellar motions in a galaxy this distant would be impossible. The researchers overcame this challenge by taking advantage of gravitational lensing, a natural cosmic magnification effect.
A second galaxy positioned between Earth and MRG-M0138 bends and refocuses the distant galaxy’s light, enlarging its image by a factor of 30. This magnification allowed the team to reconstruct the galaxy’s internal structure at a level of detail that would otherwise be unreachable.
Lead author Dr. Andrew Newman of the Carnegie Science in Pasadena, California, said: “By combining JWST data with gravitational lensing, we could peer inside the black hole’s sphere of influence, where its gravity boosts the speeds of stars. This is one of the best techniques we have to weigh a black hole, so we were excited to extend it to a much earlier period in cosmic history.”
Only a handful of dormant black holes of this size have been identified before, and all were much closer to Earth.
What the Discovery Reveals About Galaxy Evolution
The finding provides important clues about how galaxies and their central black holes evolved together in the early universe. Observations of nearby galaxies have revealed a strong link between galaxy mass and black hole mass, but researchers need more data from earlier periods of cosmic history to understand how that relationship developed.
The team found that both the black hole and its host galaxy are dormant. The galaxy is no longer producing new stars, suggesting that MRG-M0138 may once have contained a bright quasar. Researchers believe that as the black hole rapidly grew, the energy it released either heated or expelled the gas needed to form new stars, effectively shutting down star formation.
Scientists expect future observations with JWST and other space telescopes to uncover many more dormant black holes from the early universe. These discoveries could reveal more about how black holes suppress star formation and how dormant black holes can become active again when fresh material begins flowing into them.
Reference: “A stellar dynamical mass measurement of an inactive black hole at redshift 2” by Andrew B. Newman, Meng Gu, Sirio Belli, Richard S. Ellis, Sai Gangula, Jenny E. Greene, Jonelle L. Walsh, Sherry H. Suyu, Sebastian Ertl, Gabriel Caminha, Giovanni Granata, Claudio Grillo, Stefan Schuldt, Tania M. Barone, Simeon Bird, Karl Glazebrook, Marziye Jafariyazani, Mariska Kriek, Allison Matthews, Takahiro Morishita, Themiya Nanayakkara, Justin D. R. Pierel, Ana Acebrón, Pietro Bergamini, Sangjun Cha, Jose M. Diego, Nicholas Foo, Brenda Frye, Yoshinobu Fudamoto, M. James Jee, Patrick S. Kamieneski, Anton M. Koekemoer, Asish K. Meena, Shun Nishida, Masamune Oguri, Piero Rosati and Adi Zitrin, 4 June 2026, Science.
DOI: 10.1126/science.adx5816
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