They are called UFOs, but aliens have nothing to do with them. These are ultra-fast streams: cosmic winds blowing near the speed of light from around supermassive black holes. An international team of researchers investigated this still understudied phenomenon to look for these gas emissions, which are crucial to understanding the mechanisms that govern the behavior of supermassive black holes during their active phase.

The research project is called SUBWAYS (Super Massive Black Hole Winds in X-rays), and initial results are Astronomy and Astrophysics. The first of these, led by scientists from the University of Bologna and INAF, relies mainly on data from ESA’s XMM-Newton space telescope.

The scientists analyzed 22 active galactic nuclei (AGNs), the regions surrounding supermassive black holes at the center of galaxies and emitting large amounts of radiation across the electromagnetic spectrum when the black holes are in an active phase. The study found that about 30% of the active galactic nuclei analyzed have cosmic winds that move at speeds between 10% and 30% of the speed of light.

“These results allow us to detect with greater precision that a significant proportion of active galactic nuclei contain ultrafast winds, ultrafast flows, called UFOs,” explains Marcella Brusa, professor and INAF collaborator and coordinator at the University of Bologna. “And we were able to confirm that the intensity of these gas streams is sufficient to significantly change the ecosystem of their galaxy.”

A supermassive black hole and its surrounding galaxy actually have a close relationship that mutually influences their formation and evolution. The mechanisms underlying this interrelation are still poorly understood, but there may be ultrafast winds emitting active galactic nuclei between the major components. These powerful eruptions occur when some of the gas in the accretion disk is ejected outward, thereby transferring some of the matter and energy produced into interstellar space, a mechanism important in regulating the star formation process.

To detect UFOs, spectra emitted in the X-ray range are analyzed looking for absorption from the presence of highly ionized materials such as iron. This phenomenon is associated with extreme temperatures (up to tens of millions of degrees) that form near supermassive black holes. With this in mind, SUBWAYS scientists were able to achieve 1.6 million seconds of observation time (over eighteen days) with ESA’s XMM-Newton X-ray Space Telescope. In this way, they studied 17 active galactic nuclei in the relatively nearby Universe (about 1.5 to 5 billion light-years) and added to them more data than the 5 AGNs already collected in previous observations.

“These observations provide us with new independent evidence for the presence of highly ionized matter ejected at near-light speeds from the deepest regions of active galactic nuclei,” says Gabriele Mazzeu, a researcher at the University of Bologna. . INAF employee and first author of the article presenting the results of the UFO statistics. “These results allowed us to learn more about these ultrafast winds and better understand their role in shaping the evolutionary process of the galaxy.” Source