Resonant Excitation of Density Waves in Galaxies

Abstract

Linear kinetic theory is eveloped to describe the resonant Landau-type excitation of spiral density waves in a self-gravitating, rapidly and nonuniformly rotating, spatially inhomogeneous, and collisionless stellar disk of flat galaxies. This Landau excitation of waves is suggested as a mechanism for the formation of observable nonradial structural features, such as spiral arms, and the slow dynamical relaxation of disk galaxies, in a parameter regime of Jeans stability.