Using gaseous disks to probe the geometric structure of elliptical galaxies

The preferred plane of the galaxy into which the cold gas residing in the core of an elliptical galaxy settles depends on the gross geometric shape of the galaxy, with an alignment of the angular momentum vector of the gas with the longest axis in the case of a prolate galaxy and with the shortest axis in the case of an oblate form. A numerical model shows that the time scale on which this settling occurs is short where the gas disk is less than 10 kpc in size. Knowledge of gaseous disk preferred orientation in an elliptical galaxy allows the deciphering of the geometric structure of 12 galaxies with gas in their cores. Both oblate and prolate galaxies are found, and the intrinsic axial ratio of most of the galaxies is derived, without assumptions as to why the group of stars defining each galaxy is shaped as it is.