Three-Dimensional Models for the Distribution of Mass in Galaxies

Abstract

From Toomre’s (1963) disk models of galaxies, we have generalized other convenient pairs of functions to represent the axisymmetric potential and density of models in which the mass is no longer confined to a single plane. These new pairs of functions include some that vary continuously from Kuzmin’s (1956) thin-disk model to Plummer’s (1911) spherical model for globular clusters. The models are free from singularities and involve functions that are quite explicit and elementary. Even without superposing any of them, the present density laws seem to mimic remarkably well the stratifications of mass both in the central bulges and in the disk parts of real galaxies.