An international team of researchers has observed for the first time the evolution of hot gas from an active black hole. In their observations, they noticed that these structures are very reminiscent of the smoke currents produced by volcanic eruptions, with unprecedented detail and on a time scale of one hundred million years, as published in the journal ‘Nature Astronomy’.

The study focused on the Nest200047 system, a group of about 20 galaxies located about 200 million light years away. The central galaxy of this system is home to an active black hole around which the researchers observed many pairs of gas bubbles of various ages, some unknown filaments of magnetic fields, and relativistic particles in special relativity up to hundreds of thousands of light-years away.

These observations were made possible by LOFAR (LOw Frequency ARray), the world’s largest low-frequency radio telescope. LOFAR can intercept radiation produced by the oldest electrons that can be detected today. This state-of-the-art tool, the result of great efforts by nine European countries, has allowed researchers to “go back in time” to more than 100 million years ago and track the activity of the black hole at the center of Nest200047.

“Our research shows how these black hole-accelerated gas bubbles expand and transform over time. In fact, they create spectacular mushroom-shaped structures, rings, and filaments that are similar to those that originate in a powerful volcanic eruption in planet Earth “, says Marisa Brienza, first author of this study and researcher at the Augusto Righi Department of Physics and Astronomy of the University of Bologna and member of the Italian National Institute of Astrophysics (INAF).

Black holes change the evolution of a galaxy
At the core of every galaxy is a supermassive black hole. The activity of this black hole has a crucial impact on the evolution of the galaxy and the intergalactic environment that hosts it. For years, researchers have tried to find out how and at what rate the action of these black holes produces these effects.

When active, black holes consume their surroundings and, in the process, release enormous amounts of energy. Sometimes this energy comes in the form of streams of particles that move at close to the speed of light and produce radio waves. In turn, these currents generate bubbles of particles and magnetic fields that, by a process of expansion, can heat and move the intergalactic medium that surrounds them. This greatly influences the evolution of the intergalactic environment itself and, consequently, the rates of star formation.

This study, conducted by an international team of researchers from Italy, the Netherlands, Germany, Russia, the United Kingdom, South Africa, Japan and France, proposes that active black holes have effects at scales that are up to 100 times larger than the galaxy than those harbors and that this impact lasts up to hundreds of millions of years.