Black hole weighed at a distance of 10 billion light-years by JWST

An international team of astronomers, including researchers from University College London (Ucl), has successfully detected and weighed the most distant dormant black hole ever identified. Located at the center of the galaxy Mrg-M0138, more than 10 billion light-years away, this inactive black hole is 15 times farther than any previous discovery of its kind. Observing this cosmic object provides unprecedented insights into the early universe, as it is captured at an epoch when the cosmos was only about 3 billion years old, roughly a quarter of its current age.

Discovery and measurement of the most distant dormant supermassive black hole

To uncover this elusive black hole, which has a mass approximately 6 billion times that of the Sun, the research team utilized data from the Nasa James Webb Space Telescope (Jwst). Because dormant black holes do not emit light through the accretion of matter, their existence can only be inferred by tracking the collective motion of surrounding stars. By measuring the velocities of these stars, the team could calculate the gravitational pull exerted by the central hidden mass.

While this method, known as stellar dynamics, is routinely applied to study dormant black holes in galaxies relatively close to Earth, this study marks the first time the technique has been successfully deployed at such a vast cosmological distance. Prior to this achievement, the most distant galaxy analyzed via stellar dynamics was located merely 700 million light-years away. Professor Richard Ellis from Ucl Physics & Astronomy noted that determining how stars move collectively within the core of this distant galaxy allowed the team to measure a supermassive black hole that would otherwise remain completely undetectable.

Professor Ellis further emphasized that demonstrating the feasibility of this technique for early universe galaxies opens the door to a comprehensive census of black hole development over time. This advancement will allow scientists to deduce the precise role these objects play in shaping galactic evolution. The precise measurement achieved by the team confirms that the speed of the stars increases significantly within the sphere of influence of the black hole, proving the reliability of the stellar dynamics approach even at extreme distances.

Gravitational lensing as a cosmic magnifying glass

Observing individual stellar movements at a distance of 10 billion light-years would normally be impossible with current technology. To overcome this formidable barrier, the astronomers relied on a natural cosmic phenomenon known as gravitational lensing. The gravitational field of a massive foreground galaxy, perfectly aligned between Earth and Mrg-M0138, deflected and refocused the light coming from behind it.

This gravitational distortion acted as a powerful natural magnifying glass, amplifying the background image of the galaxy by a factor of 30. By leveraging this exceptional enhancement, the researchers managed to reconstruct the internal structure of the distant galaxy with a much higher resolution than standard observations would permit. Dr Andrew Newman from Carnegie Science, the lead author of the study, explained that combining Jwst data with gravitational lensing allowed them to peer directly into the core of the galaxy where gravity accelerates stellar velocities.

Dr Newman expressed great enthusiasm about extending one of the best available mass-quantification techniques to such a remote period of cosmic history. Without the alignment provided by gravitational lensing, the subtle differences in stellar motion between the stars closest to the black hole and those farther away would have been entirely blurred. The success of this observation establishes a new precedent for using cosmic magnification to study the intimate mechanics of the ancient universe.

Coevolution of galaxies and the suppression of star formation

The discovery of this dormant giant offers vital clues regarding how black holes and their host galaxies formed and evolved together during the infancy of the universe. Modern local galaxies exhibit a tight, proportional relationship between their total mass and the mass of their central black holes. However, gathering more data from remote cosmic epochs is essential to understand whether this correlation held true in the early universe for both active and inactive systems.

In addition to the black hole being dormant, the researchers discovered that the surrounding galaxy Mrg-M0138 is also completely quiescent, meaning it has ceased to form new stars. Evidence suggests that this galaxy likely hosted a luminous quasar in its distant past, powered by large amounts of gas falling into the black hole and emitting immense radiation. When the black hole grew rapidly during this active phase, the energy it released likely heated or expelled the cold gas reservoirs required for star birth.

The research team anticipates that future observations with the Jwst and other advanced space telescopes will reveal many more dormant black holes dating back to the early universe. A larger sample size would clarify the exact mechanism by which these objects halt star formation across entire galaxies. Furthermore, such studies will help scientists understand how these dormant giants might eventually reactivate if a new supply of matter begins to flow back into their gravitational centers.

The study is published in Science.