With the help of the NASA Chandra X-ray Observatory, researchers obtained data on thousands of black holes living near the center of the Milky Way. This wealth is represented by black holes of stellar mass, the weight of which usually reaches 5-30 solar masses. They were found within three light years from the supermassive black hole Sagittarius A *.
Theoretical studies of stellar dynamics in galaxies have shown that a large population of stellar-mass black holes (approximately 20,000 pieces) can drift inward according to eons and gather around Sagittarius A *.
By itself, the black hole remains invisible. However, when approaching the object, it begins to pull the gas out of the satellite. The material falls into the disk and warms up to millions of degrees, due to which X-rays are released. Some of these X-ray binaries are noted on Chandra images.
Researchers at Columbia University in New York used this information to search for X-ray binaries containing black holes near Sagittarius A *. They studied X-ray spectra at a distance of 12 light-years from the central supermassive black hole. Then selected sources with x-ray spectra corresponding to the indicators of binary systems. Thus, we managed to find 14 points at a distance of 3 light years from Sagittarius A *. Two of them probably contain x-ray stars. The dozens remaining are marked with red circles, and other sources are marked with white. Analysis shows that most of the doubles contain black holes. But it is important to note that only the brightest double objects appear in the review. Therefore, we can assume that there is a large, weak population of non-found X-ray sources (from 300 to thousands) with black holes.
This discovery not only helps to understand the process of formation of X-ray twins, but also contributes to the study of gravitational waves. With Sagittarius A *, there should be an even larger population of stellar-mass black holes without accompanying stars. The theory indicates the presence of more than 10,000-40000 black holes in the center.