On the Formation of Warped Gas Disks in Galaxies
  We consider the most commonly occurring circumstances which apply to
galaxies, namely membership in galaxy groups of about $10^{13}h^{-1} M_\odot$
total mass, and estimate the accompanying physical conditions of intergalactic
medium (IGM) density and the relative galaxy-IGM space velocity. We then
investigate the dynamical consequences of such a typical galaxy-IGM interaction
on a rotating gaseous disk within the galaxy potential. We find that the
rotating outer disk is systematically distorted into a characteristic "warp"
morphology, of the type that has been well-documented in the majority of
well-studied nearby systems. The distortion is established rapidly, within two
rotation periods, and is long-lived, surviving for at least ten. A second
consequence of the interaction is the formation of a one arm retrograde spiral
wave pattern that propagates in the disk. We suggest that the ubiquity of the
warp phenomenon might be used to reconstruct both the IGM density profile and
individual member orbits within galaxy groups.
