Astrophysicists have discovered why fewer stars are forming in space than expected

An international team of astronomers led by Congyae Zhang from the Department of Theoretical Physics and Astrophysics at the Faculty of Science has discovered turbulent movements of intergalactic gas caused by a supermassive black hole at the center of the Perseus galaxy cluster. The results of the study were published in the prestigious scientific journal Nature and provide new insights into how supermassive black holes influence the evolution of galaxies and suppress star formation.

Only about 15 percent of the mass of the universe consists of "normal" matter composed of atoms, while the remaining 85 percent is accounted for by the still mysterious dark matter. Furthermore, research over the past 25 years has shown that less than 10 percent of normal matter is found in stars and galaxies. Most of it is very rarefied hot gas filling the space between galaxies, which emits X-rays that can be observed using space telescopes.

A major breakthrough has been made by the new Japanese X-ray observatory XRISM, which provides astronomers with an unprecedented detailed view of the dynamics of hot gas in galaxy clusters. For the first time, it was possible to accurately map the velocities of intergalactic gas in the Perseus galaxy cluster. Measurements showed that the supermassive black hole at its center, approximately 200 times more massive than the black hole in our galaxy, causes chaotic turbulent motions with velocities of up to about 200 kilometers per second.

Contrary to the widespread notion of black holes as cosmic vacuum cleaners, it appears that they are rather "inefficient eaters." Most of the gas that flows into them is not absorbed, but rather ejected back into the surrounding space in the form of powerful jets and winds. These outflows continuously supply energy to the surrounding environment, mix hot gas, and drive the observed turbulent motions.

The lead author of the study published in Nature is Congyao Zhang from the Institute of Theoretical Physics and Astrophysics. Members of the entire international collaboration of the XRISM mission contributed to the article, and the work represents one of the key scientific results of the first years of this mission. "These results provide fundamental insights into the feedback of supermassive black holes, which could explain why only a small fraction of the ordinary matter in the universe is converted into stars," says Zhang, who came to Masaryk University from the University of Chicago in 2024.

It has long been assumed that hot intergalactic gas in galaxy clusters will gradually cool, condense, and form new stars. However, observations using the XRISM satellite suggest that turbulence driven by supermassive black holes plays a key role in heating this gas and effectively preventing the formation of new stars.

You can read the publication in Nature here.