Why Are Rotating Elliptical Galaxies Less Elliptical at X‐Ray Frequencies?

If mass and angular momentum were conserved in cooling flows associated withluminous, slowly rotating elliptical galaxies, the inflowing hot gas would spinup, resulting in disks of cold gas and X-ray images that are highly flattenedalong the equatorial plane out to several effective radii. Such X-rayflattening is not observed at the spatial resolution currently available toX-ray observations. Evidently mass and angular momentum are not in factconserved. If cooling flows are depleted by localized radiative cooling atnumerous sites distributed throughout the flows, then disks of cooled gas donot form and the X-ray images appear nearly circular. However, the distributionof young stars formed from the cooled gas is still somewhat flattened relativeto the stellar light. X-ray images of galactic cooling flows can also becircularized by the turbulent diffusion of angular momentum away from the axisof rotation, but the effective viscosity of known processes -- stellar massloss, supernovae, cooling site evolution, etc. -- is insufficient toappreciably circularize the X-ray images. Radial gradients in the interstellariron abundance are unaffected by the expected level of interstellar turbulencesince these gradients are continuously re-established by Type Ia supernovae.Comment: 17 pages with 6 figures; accepted by Astrophysical Journa