Black Holes and Galaxies

Scientists found indirect ways of doing so. The methods depends upon black holes being members of binary star systems. A binary star system consists of two stars comparatively near to and revolving about each other. Unlike our Sun, most stars exist in pairs.

If one of the stars in a binary system had become a black hole, the hole would betray its existence, although invisible, by its gravitational effects upon the other star. These effects would be in accordance with Newton's Law: attractions of two bodies to each other are directly proportional to the square of the distance between them. The reason is that outside of its event horizon, a black hole's gravity is the same as other objects'.

Scientists also have determined that a substantial part of the energy of matter spiraling into a black hole is converted by collision, compression, and heating into X- and gamma rays displaying certain spectral characteristics. The radiation is from the material as it is pulled across the hole's event horizon, its radiation cannot escape.