Study finds 'supermassive' black holes may be smaller than thought, new measurements in the early universe

Scientists have published findings that a black hole at the center of a galaxy 12 billion light-years away may be far smaller than previously believed. Using the GRAVITY+ instrument to observe the infant galaxy, researchers measured a black hole mass of about 800 million solar masses, roughly one-tenth of the mass that earlier estimates indicated. The study, published in Astronomy & Astrophysics, challenges assumptions about the masses of supermassive black holes in the early universe and could affect models of cosmic evolution.

The team studied gas dynamics near the black hole, tracing how gas swirls around the event horizon and using precise measurements to weigh the object. Observations were made with the European Southern Observatory's Very Large Telescope, combining light from four telescopes to create a virtual 100-meter-scale instrument. By mapping both the position and speed of the gas, the researchers derived a more accurate mass for the black hole.

Co-author Professor Seb Hoenig of the University of Southampton said the findings show that existing methods to weigh such black holes in the distant universe are not reliable. The results imply that the masses of some high redshift black holes may have been systematically overestimated, with implications for models of how cosmic structures evolved.

Dr. Richard Davies of the Max Planck Institute for Extraterrestrial Physics noted that earlier estimates relied on relationships calibrated with nearby black holes, which might not apply in the early universe.

The study also found that the black hole was accreting gas at a high rate and driving a rapid outflow of material. The outflow is moving at about 6,200 miles per second (10,000 kilometers per second). The researchers suggest this radiation-driven wind could have influenced the observed gas dynamics, contributing to the prior overestimation of mass.

If the pattern holds for other distant black holes, the finding could affect theories about how galaxies and their central black holes grew in the early universe. Researchers emphasize that more work is needed to determine how common such biases are.

The study demonstrates the role of GRAVITY+ in refining black hole mass measurements by combining the light of the four Unit Telescopes of the Very Large Telescope. The instrument helps achieve resolution sufficient to study gas motion close to black holes.

The Astronomy & Astrophysics paper lists Hoenig, Shimizu, Davies and colleagues as authors. The research adds to ongoing efforts to map the growth of black holes during the universe's first few billion years.