Dynamical processes in self-gravitating disks

I will start by reviewing key dynamical processes at the basis of the excitation and maintenance of spiral structure in galaxies and focus on the dynamical coupling/decoupling between the cooler component, dominated by the dissipative gas, and the more massive underlying collisionless stellar component of the disk. This important dynamical factor can now be probed observationally by comparing images in the optical with images taken in the near-infrared. I will then consider the formation of an ideal gaseous disk and show that self-gravity helps organize the accretion process in such a way that the disk density distribution is characterized by a flat rotation curve.