Using an array of ALMA radio telescopes, astronomers were able to view a disk of cold interstellar gas encircling a supermassive black hole in the center of the Milky Way, as well as track its rotation.
For the first time, we managed to see this elusive disk, estimate its mass and study the movement of gas in it. Over the decades of research, we have drawn a fairly clear picture of a gravitational monster chaotic and filled with various objects in the center of our galaxy, but some details still elude our telescopes, and we still manage to make new discoveries.
At a distance of about 26 thousand light-years from Earth in the direction of the center of the Milky Way is the object Sagittarius A*, which, according to astronomers, is a supermassive black hole exceeding the mass of the Sun 4 million times.
Today we know that his surroundings are filled with wandering stars and interstellar dust clouds. In addition, it contains a large amount of both phenomenally hot and relatively cold gas, which are believed to revolve around Sagittarius A*, forming a huge accretion disk extending a few tenths of a light year from its event horizon.
So far, however, we have managed to display only an insignificant, hot part of the gas stream, heated to 10 million degrees Celsius. At such a temperature, matter glows fiercely in the X-ray range, and this makes it possible to study it with the help of space X-ray telescopes.
It is much more difficult to see clouds of colder gas because of the complexity of the observations, however, astronomers have found a way to do this. Despite the fact that the source Sagittarius A* is relatively quiet, the radiation around it is strong enough that the hydrogen atoms constantly lose their electrons and recombine. This leads to the emission of a characteristic millimeter wavelength signal, which is capable of reaching the Earth with very small losses.
With its remarkable sensitivity and ability to see small details, ALMA was able to capture just this weak radio signal and create the first image of a cold gas disk (10 thousand degrees Celsius), removed only 1000 astronomical units from the supermassive black hole in the heart of the Milky Way.
The observations, the researchers note, allowed them to both map the location and track the movement of this ring out of gas, whose mass is estimated to be about one-tenth of Jupiter’s mass or one ten-thousandth of the Sun’s mass.
We are getting closer and closer“ getting closer ”to our supermassive black hole, but the riddles still remain. I hope that the observations made at ALMA will help in the future to reveal some of its secrets, ”concluded Elena Murchikova, lead author of the study from the Institute for Advanced Studies in Princeton (USA).
Ring around a black hole in the center of the Milky Way
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