An international team of astronomers led by Carnegie Science researcher Andrew Newman has achieved the first direct measurement of a dormant black hole in a distant galaxy from the early Universe.
The dormant black hole resides at the centre of MRG-M0138, a massive galaxy located around 10 billion light-years from Earth.
A new way to study dormant black holesUnlike actively feeding black holes, which can be detected through the intense radiation they produce as they consume surrounding gas, a dormant black hole emits little or no visible energy.
Gravitational lensing provides a cosmic magnifying glassA key factor behind the discovery was gravitational lensing.
The newly measured dormant black hole suggests that some of the densest galaxies may have experienced rapid black hole growth early in cosmic history.
An international team of astronomers led by Carnegie Science researcher Andrew Newman has achieved the first direct measurement of a dormant black hole in a distant galaxy from the early Universe.
Using observations from the James Webb Space Telescope (JWST), researchers calculated the mass of the inactive giant at approximately 6 billion times that of the Sun.
The dormant black hole resides at the centre of MRG-M0138, a massive galaxy located around 10 billion light-years from Earth.
The galaxy is observed as it existed when the Universe was only about three billion years old, providing researchers with a rare opportunity to investigate black hole growth during a critical stage of cosmic evolution.
The breakthrough was made possible by combining JWST’s advanced imaging capabilities with gravitational lensing, a natural magnification effect created by a foreground galaxy cluster.
The findings provide some of the strongest evidence yet that supermassive black holes and their host galaxies were already evolving together in the early universe.
A new way to study dormant black holes
Unlike actively feeding black holes, which can be detected through the intense radiation they produce as they consume surrounding gas, a dormant black hole emits little or no visible energy. This makes such objects significantly harder to identify and study.
To overcome this challenge, the research team measured the movement of stars near the centre of MRG-M0138. The gravitational pull of the black hole causes nearby stars to travel at higher speeds, allowing astronomers to estimate the black hole’s mass indirectly.
This technique has previously been used to measure black holes in relatively nearby galaxies. However, applying it to a galaxy located billions of light-years away had remained beyond the reach of existing technology until the arrival of JWST.
Gravitational lensing provides a cosmic magnifying glass
A key factor behind the discovery was gravitational lensing. MRG-M0138 sits behind a massive cluster of galaxies whose gravity bends and magnifies the light from the distant galaxy.
The lensing effect enlarged the appearance of MRG-M0138 by roughly 30 times, enabling JWST to resolve details that would otherwise be impossible to observe.
This allowed astronomers to study the motions of stars within the region dominated by the black hole’s gravity, often referred to as its sphere of influence.
By combining these two powerful tools, researchers were able to perform one of the most challenging black hole measurements ever attempted.
Insights into galaxy evolution
The discovery offers important clues about how the largest black holes formed and grew during the universe’s early history.
Astronomers have long observed a close relationship between the mass of a galaxy’s central black hole and the characteristics of the surrounding galaxy.
However, determining whether this connection existed billions of years ago has proven difficult due to the lack of direct measurements from the distant universe.
The newly measured dormant black hole suggests that some of the densest galaxies may have experienced rapid black hole growth early in cosmic history. This supports the idea that black holes played a major role in shaping the development of galaxies.
Researchers also believe MRG-M0138 was likely once home to a powerful quasar. During that phase, enormous amounts of energy released by the growing black hole may have heated or expelled gas needed for star formation. This process could explain why both the galaxy and its central black hole are now inactive.
Future telescopes could reveal more hidden giants
The measurement marks an important milestone, but astronomers expect many more discoveries to follow.
Scientists are already analysing additional JWST observations of similar galaxies. Upcoming missions, including the Euclid satellite and the Nancy Grace Roman Space Telescope, are expected to uncover significantly more examples of gravitational lensing across the universe.
Meanwhile, the Giant Magellan Telescope, currently under construction in Chile, will provide even greater precision for studying stellar motions in distant galaxies.
By applying these techniques to a larger sample of galaxies, researchers hope to uncover how the most massive dormant black holes formed, how quickly they grew, and how they influenced the evolution of galaxies throughout cosmic history.
