An international team of researchers, including academics from the University of Bologna and the Italian National Institute of Astrophysics (INAF), observed for the first time the evolution of hot gas from an active black hole. They were able to observe these structures, which are strongly reminiscent of the flow of smoke produced by volcanic eruptions, with unprecedented detail and on a time scale of one hundred million years.
Their study, published in Nature astronomy, focused on the Nest200047 system, a group of about 20 galaxies about 200 million light years away. The central galaxy of this system is home to an active black hole around which the researchers observed numerous pairs of gas bubbles of various ages, unknown filaments of magnetic fields and relativistic particles in special relativity up to hundreds of thousands of light years.
These observations were made possible thanks to the LOFAR (LOw Frequency ARray), the largest low-frequency radio telescope in the world. LOFAR can intercept the radiation produced by the oldest electrons currently detectable. This cutting-edge tool was born out of the great effort of nine European countries and has enabled researchers to “go back in time” over 100 million years ago and trace the activity of the black hole sitting at the center of Nest200047.
“Our investigation shows how these gas bubbles accelerated by the black hole expand and transform over time. Indeed, they create spectacular mushroom-shaped structures, rings and filaments similar to those from a powerful eruption. volcanic on planet Earth “, declares Marisa Brienza who is the first author of this study and researcher at the Department of Physics and Astronomy” Augusto Righi “of the University of Bologna and member of the INAF.
Bubbles made of particles
At the heart of every galaxy is a supermassive black hole. The activity of the 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 understand how and how quickly the action of these black holes produces these effects.
When active, black holes consume everything around them, and in the process, they release huge amounts of energy. Sometimes this energy comes in the form of a stream of particles moving at a speed close to light and producing radio waves. In turn, these flows generate particle bubbles and magnetic fields which, through a process of expansion, can heat and displace the intergalactic medium around them. This has an immense influence on the evolution of the intergalactic medium itself and, consequently, on the rates of star formation.
This study proposes that active black holes have effects at scales up to 100 times the size of the host galaxy and that this impact lasts for up to hundreds of millions of years.
“LOFAR has given us a unique view of the activity of black holes and their effects on their surrounding environment,” says Annalisa Bonafede, one of the study’s authors and professor at the University of Bologna as well as member of INAF. “Our observations from Nest200047 crucially show how magnetic fields and very old particles accelerated by black holes and therefore aged play a central role in the transfer of energy to the outer regions of clusters of galaxies.”
For this study, the researchers also used in-band X-ray observations obtained using the eROSITA telescope aboard the SRG space observatory. The X-ray data allowed researchers to better study the characteristics of the intergalactic medium surrounding the bubbles of radio-emitting gas.
These observations led to other unexpected discoveries: thin gas filaments as long as a million light years made of particles moving at approximately the speed of light.
According to the researchers, these filaments are the remnants of the bubbles that the black hole Nest200047 produced hundreds of millions of years ago and which are now shattering and mixing with the intergalactic medium. It is believed that the study of these structures will lead to the discovery of new and important information about the physical characteristics of intergalactic matter and the physical mechanism regulating the transfer of energy between bubbles and the external environment.
“In the future, we will be able to study the effects of black holes on galaxies and the intergalactic environment in more and more detail. Ultimately, we will be able to reveal the nature of the filaments that we have discovered thanks to the angular resolution of LOFAR combined with data from international LOFAR stations ”, adds Gianfranco Brunetti, co-author of this study as well as an astrophysicist at INAF Bologna. and Italian coordinator of the LOFAR consortium.
LOFAR is managed by ASTRON, the Dutch Institute for Radio Astronomy, and is made up of thousands of antennas hosted by 51 radio stations scattered across different European countries. LOFAR can intercept the lowest frequencies of radio waves on Earth (between 10 and 240 mega-Hertz). The National Institute of Astrophysics (INAF) is at the head of the Italian LOFAR team and contributes to the development of a new generation of electronic devices for the telescope and the software regulating its operation.
The SRG spacecraft was designed by the Lavochkin Association, as part of the Roskosmos company and launched on July 13, 2019 with a Proton launcher from the Baikonur Cosmodrome. The SRG Observatory was built with the participation of the German Aerospace Center (DLR) as part of the Russian Federal Space Program on the initiative of the Russian Academy of Sciences represented by its Institute for Space Research (IKI). The eROSITA telescope was built under the direction of the Max-Planck-Institute for Extraterrestrial Physics (MPE) and the DLR. The SRG spacecraft is operated by the Lavochkin Association and Deep Space Network Antennae at Bear Lakes, Ussurijsk and Baykonur funded by Roskosmos.
This study is titled “A Snapshot of Older AGN Feedback Phases” and was published in Nature astronomy. It is the result of a combined effort of experts in radio, optical and X-ray astronomy from: Università di Bologna, INAF-IRA, INAF-OAT, INAF-IASF, ASTRON, Leiden Observatory, Hamburger Sternwarte, Kazan Federal University, Academy of Sciences of Tatarstan, Space Research Institute (IKI), Max Planck Institute for Astrophysics, University of Hertfordshire, DIAS, SRON, University of Tokyo, Observatoire de Paris (GEPI, USN), Rhodes University.
Help find the location of the newly discovered black holes in the LOFAR Radio Galaxy Zoo project
Marisa Brienza, A Snapshot of the Earliest Feedback Phases of Active Galactic Nuclei, Nature astronomy (2021). DOI: 10.1038 / s41550-021-01491-0. www.nature.com/articles/s41550-021-01491-0
Provided by Università di Bologna
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