At the center of many galaxies sits a supermassive black hole. When gas falls onto it, the gas heats up and shines brighter than an entire galaxy: this is an active galactic nucleus. Sometimes a true hurricane erupts from there: a stream of ionized gas racing at tens of percent of the speed of light. In the X-ray spectrum, it leaves a mark — a dark absorption band shifted toward higher energies.

Astronomers took 33 observations of 33 bright active nuclei from the XMM-Newton space observatory (an X-ray telescope operating in orbit since 1999). For the first time, they searched for such winds up to an energy of 12 keV — previously they had limited themselves to 10 keV. In six out of 33 cases, they found a reliable signal: the probability of a chance coincidence is less than 5%. The wind speed in one source exceeded 40% of the speed of light — faster than in previous samples.

They checked the connection with the black hole's appetite — how fast it swallows matter. It turns out there is no connection: the wind blows both for gluttons and for those that eat slowly. However, they noticed that the wind is not constant: in the same source, it appears and disappears between observations. This is the first systematic check up to 12 keV, and it showed that such hurricanes occur in 18% of bright active nuclei.