Astrophysicists think that there are tens of thousands of black holes at the centre of our galaxy. This hypothesis is based on the probable discovery of a dozen smaller black holes around the enormous black hole in the centre of the Milky Way, Sagittarius A.
The astronomers have found evidence for the presence of a dozen black holes around Sagittarius A by looking for less fierce, but more consistent X-rays that occur after the merging of an X-ray binary star. In addition, the binary star system is in an inactive state. The astronomers specifically searched for the bond between a black hole and a star with a relatively low mass, because the radiation is more consistent with these double stars than with double stars with heavier stars. In the search, scientists from Columbia University used to archive data from NASA’s Chandra X-ray Observatory. On the basis of the data, twelve have been found that are within three light years of Sagittarius A.
According to the scientists, this discovery is a confirmation of a theory that has existed for decades that thousands of black holes around supermassive black holes must be present. . By extrapolating the results on the basis of analyzes of where such discovered binary star systems are located in space, the scientists state that between 300 and 500 X-ray double stars with stars with relatively little mass should be in the same environment of the twelve discovered double stars, with another ten thousand black holes.
Until now scientists have mainly looked for these black holes by looking at the bright x-rays emitted at the moment such a black hole the true binds to a passing star and thus forms an X-ray binary star. A large amount of X-rays is released during this process. According to the researchers, this has yielded little, because the center of the Milky Way is so far away that such radiation is only strong and clear enough once every hundred or thousand years. In addition, the search for individual black holes is also difficult, because they are only black and have little activity.
According to the astronomers, their research can mean a lot for research into gravitational waves, because it is important for research in this field to know how many black holes there are in the centre of an average galaxy. Eventually, it becomes possible to better predict how many gravity effects can be associated with black holes. The research was published in the scientific journal Nature, under the title ‘A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy’.