The center of active galaxies is the site of a wide range of activity aparently powered by the black hole. X-rays and gamma-rays are emitted from the area, and rapidly moving gas clouds can be observed there. Data strongly indicates that material is being pulled into the black hole from outside the nuclear region, including some gas from the z direction (i.e., perpendicular to the galactic plane). As the gas nears the black hole, its strong gravitational force squeezes the gas into a rapidly rotating disk, which extends outward about five to 30 light-years from the central object. Rotation measurements of these disks indicate that their black holes have a mass roughly 4,000,000 times that of the Sun.