The Origin of Parsec-Scale Gaseous and Stellar Disks in the Galactic
  Center and AGNs
  The Galactic center stellar disk and the circumnuclear ring provide a unique
opportunity to study in detail the dynamics and physical conditions of distant
molecular disks in the nuclei of galaxies. One of the key questions is how
these disks form so close to their host black holes and under what condition
they form stars in a tidally stressed environment. We argue that disk formation
around a massive black hole is due to partial accretion of extended molecular
clouds that temporarily pass through the central region of the Galaxy. The
cancellation of angular momentum of the gravitationally focused gas naturally
creates a compact gaseous disk. The disk can potentially become gravitationally
unstable and form stars. We apply these ideas to explain the origin of
sub-parsec megamaser disks found in the nuclei of Seyfert 2 galaxies. We show
that an empirical scaling relation between the mass of the black hole and the
size of the disk can be understood in the context of the cloud capture
scenario. We conclude that the stellar and gas disks found in our Galactic
center act as a bridge to further our understanding of more distant mega-maser
disks in the nuclei of Seyfert 2 galaxies.
