Formation of Galactic Disks
  We review progress in understanding the formation of galactic disks in the standard cosmogonic scenario involving gravitational clustering of baryons and dark matter and dissipative collapse of the baryons. This scenario accounts remarkably well for the observed properties of galactic disks if they have retained most of the specific angular momentum they acquired by tidal torques. Early simulations, which included cooling of the gas but not star formation and the associated feedback, indicated instead that most of the angular momentum of the baryons would be transferred to the dark matter. Recent simulations indicate that this angular-momentum problem can be solved partially, and in some cases entirely, by feedback and other effects. 
S. Michael Fall