Formation and rotation of disc galaxies with haloes.

The paper discusses disk galaxies formed from collapsing gas in extended haloes of dark material. It was assumed that these systems were produced by hierarchical clustering and have angular moments from tidal torques. Models were developed to determine the structure of the haloes in terms of observable properties of the disks. It was shown that: (1) collapse factors of 10 or more and halo-to-disk mass ratios of 5 or more are necessary to explain the rapid rotation of the disks; (2) the halo rotation curves computed on the basis of detailed conservation of angular momentum in the disks are flat, and (3) most disks are globally unstable to the formation of non-axisymmetric perturbations unless their mass-to-light ratios are much smaller than current estimates.