The Remarkable Twisted Disk of NGC 4753 and the Shapes of Galactic Halos

The complex dust lanes in the S0 galaxy NGC 4753 are shown to be consistent with a disk that is strongly twisted by differential precession. Yet another peculiar S0 can therefore be explained as the result of an accretion event. Am evolving disk model is fitted to the observed dust distribution. This disk is inclined by 15^deg^ relative to the galaxy's equatorial plane and twisted such that its line of nodes changes smoothly by 3.8π over a factor of seven in radius. The model shows excellent agreement between increased line-of-sight path lengths through the disk and the observed dust lanes. A nodal precession rate proportional to r^-1^ matches the observations with considerable accuracy. The model indicates that most of the galaxy's mass is unseen, is nearly spherically distributed, and has a nearly scale-free spatial distribution. The ellipticity of the total galactic mass distribution must be constant to within 20% over the radial extent of the twisted disk- a conclusion which may significantly constrain galaxy formation mechanisms. If the disk and the main body of NGC 4753 rotate in the same direction, then the sense of the twist implies an oblate galactic mass distribution. The flattening of the halo and the age of the accretion event cannot be determined independently, but physical arguments imply that the shape of the total mass distribution is between ~E0.1 and E1.6.