An international team of astronomers has measured the mass of a dormant supermassive black hole more than 10 billion light-years away, providing an unprecedented glimpse into the early universe. The research, published in Science, reveals the black hole at the center of galaxy MRG-M0138 weighs around six billion times the mass of the Sun, offering new clues about how galaxies and black holes evolved when the universe was only a quarter of its current age.
Unveiling A Cosmic Giant Hidden In Plain Sight
While active black holes often announce their presence through intense radiation, dormant black holes remain invisible, detectable only through their gravitational influence on nearby stars. In the case of MRG-M0138, astronomers relied on the stellar dynamics technique, tracking the motions of stars orbiting the galaxy’s core to calculate the black hole’s mass.
Previously, this method had only been applied to relatively nearby galaxies, with the farthest studied at 700 million light-years away. Now, JWST combined with gravitational lensing has allowed this technique to probe a galaxy located over 10 billion light-years from Earth, extending the reach of stellar dynamics deep into the early cosmos.
How JWST And Gravitational Lensing Made The Impossible Possible
The James Webb Space Telescope (JWST) played a central role in this discovery, providing high-resolution data of the highly magnified galaxy image. A foreground galaxy acts as a cosmic magnifying glass, bending and enlarging the light from MRG-M0138 by roughly 30 times. Lead author Dr. Andrew Newman of Carnegie Science explained,
“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.”
Without this fortuitous alignment, measuring the motions of stars at such a distance would have been impossible.
Weighing The Invisible: Stellar Motions Reveal Mass
The team meticulously mapped the velocities of stars across the galaxy’s central region. Stars near the black hole moved significantly faster than those farther out, reflecting the gravitational pull of a hidden giant. This difference in stellar speeds allowed researchers to calculate the black hole’s mass with remarkable precision. Professor Richard Ellis of UCL Physics & Astronomy emphasized the importance of the method:
“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.”
The study, detailed in the journal Science, represents a major step toward understanding how supermassive black holes influenced the growth of galaxies in the young universe.
Implications For Early Universe Galaxy Formation
MRG-M0138 and its central black hole are both dormant, with no ongoing star formation or accretion activity. Astronomers hypothesize that during its early, luminous quasar phase, the black hole released enormous energy that likely expelled the gas necessary for forming new stars. Observing such a massive dormant black hole so far away offers a rare window into galactic evolution in the universe’s first few billion years. Future JWST observations and data from other telescopes are expected to uncover more dormant black holes, deepening our understanding of their role in regulating star formation and the lifecycle of galaxies.
