On the inner edge of the circumnuclear disc in the Galaxy

Evidence is presented showing that the comparatively sharp inner edge of the circumnuclear accretion disk, or ring, in the Galactic center is due to a change in the radial gradient of the mass distribution at about 1.8 pc. The smaller the region is over which the gradient of the potential changes, the sharper the edge will be. Therefore, it is possible to determine the change of the potential's gradient, i.e., of the mass distribution's radial gradient, by measuring the radial extent of the edge of the ring. The transition from the domain of the central object to the power-law mass distribution in this model is correspondingly sharp, which means that the mass within about the central 2 pc of the Galaxy is small compared to the mass of the central object.