Black holes are treated with caution because of their nutritional needs (they absorb the surrounding material). In fact, dust, gas and stars can rotate nearby for quite a long time, until a certain shift in the direction of the black hole occurs.
One of the violations will be the merger of two galaxies. At this point, the central black holes rush towards, absorbing the surrounding material. Such a “dinner” releases a huge amount of high-energy radiation, and a hungry black hole transforms into an active galactic core.
The NuSTAR telescope demonstrated the process of dust and gas entering a black hole at the later stages of the galactic fusion. The total gravity of two galaxies slows down the speed of rotation of gas and dust, which could move freely around. It is the loss of energy that makes the material tend to a black hole.
“The deeper the merger, the more eclipsed is the active galactic nucleus,” said study author Claudio Ricci. “The late stage will demonstrate real gas and dust cocoons.” Ricci and his colleagues tracked high-energy X-rays from 52 galaxies. Approximately half of them remained in the late stage of the merger. NuSTAR is extremely sensitive to X-rays, so scientists are eager to calculate how much light comes out of the gas and dust sphere.
If high-energy X-rays were detected, but not low-energy, then this proves the strong shading of the active galactic core. This study confirms the theory that a black hole feeds most actively in the later stages of a merger. At such moments, it is rapidly growing. New data will help to study its future behavior, as well as the relationship with the host galaxy.