Astrophysics finally found a hot wind from a black hole in the center of our galaxy

Astrophysicists discovered a hot wind bursting out of a super -massive black hole in the center of our galaxy, and this can help understand its mysterious “passivity”.

Compared to many other ultra -massive black holes in the centers of galaxies, our Sagittarius A* (SGR A*) behaves relatively calmly. She does not throw powerful giant jets, which in other black holes are so bright that they are visible from the earliest times of the universe. But it is believed that all ultra -massive black holes, including SGR A*, produce winds – flows of hot gas, breaking out of the area at the horizon of events, where the substance rotates and greatly heats up.

Such winds were predicted back in the 1970s, but so far it has not been possible to obtain reliable confirmations of their presence from SGR A*. This is partly explained by adverse observation conditions: our black hole is poorly visible inside the dense cluster of stars, gas and dust – the pre -core disk (Oyad).

With the help of the ALMA radio telescope, Mark Gorski and Elena Murchikova from the North-Western University at Illinois studied the most internal region of Oyad with unprecedented details, the results of which were divided into arXiv. They found there the vast regions of cold gas, which they did not expect to see, as well as the clear cone of hot gas cutting them out-which, apparently, is the same predictable wind.

The discovery of such a amount of cold gas was so close to a black hole, it was a mountain. In generally accepted opinion, it was pointless to look for him there, because he “should not” exist.

“When I showed this image (colleague), I said:“ Well, now we must focus on this, because this problem remains unresolved for more than 50 years, ”the scientist recalls.

Gorski and Murchikov collected Alma data for five years of observation of the internal part of the Oyad and created a cold gas map within a radius of several light years from SRR A*, which turned out to be 100 times more clearly than the previous ones. It was possible to achieve this by simulating a bright flicker from the SGR A* itself and subtracting it from the weak glow of cold gas.

As a result, a clear cone was revealed, where there is almost no cold gas. When the researchers put X -ray data (hot gas radiation) on this card, both areas coincided almost perfectly. According to calculations, the energy necessary for blowing hot gas through this cone is equivalent to the energy of about 25,000 suns. This excludes the possibility that the gas is thrown out by neighboring stars or formed by a supernova – such events are not visible there. So, the source of the wind is SRR A*itself.

“The necessary energy requires the presence of a black hole. This means that the wind really comes from it, ”explains Gorski.

Earlier, astronomers discovered giant gas bubbles above and under the plane of the galaxy-the so-called Fermi bubbles, which indicates: once our black hole was thrown out by jets. But it is not known whether they can appear again. The measurement of this wind can explain why SRR A* behaves relatively calmly, and help better understand the stage of evolution of black holes.

If the detection of the “missing wind” in SRR A* is confirmed, this will be a very important discovery – because it can give the key to understanding the black hole itself – for example, the direction of its rotation, the astrophysicist Ziri Yunsi from the University College of London noted.

It was believed that Sagittarius A* should rotate perpendicular to the plane of the Milky Way, that is, we must see it “from the rib”. But when in 2022 the first images appeared from the telescope of the horizon of events, it turned out that it was located “face to us”, although the data is not enough for the final output.

“The mass of Sagittarius A* is determined by observations very accurately, but its angle of inclination relative to us is not so defined that it can turn out to be almost anything. If these results are reliable, they will give us the first indications of where the substance comes into the black hole. And this, in turn, will help to better understand how our Galaxy developed, ”Yuns summed up.