Why are rotating elliptical galaxies less elliptical at X-ray frequencies?

If mass and angular momentum are conserved in the cooling flows associated with luminous, slowly rotating elliptical galaxies, the flow cools onto ext ended, massive disks of rotationally supported cold gas in the equatorial p lane. As the hot interstellar gas approaches the disks, its density and the rmal X-ray emission increase, resulting in X-ray images that are considerab ly flattened toward the equatorial plane out to an optical effective radius or beyond. Remarkably, the flattening of X-ray images due to rotation is v ery small or absent at the spatial resolution currently available to X-ray observations. This is strong evidence that mass and angular momentum are no t in fact conserved. In particular, if cooling flows are depleted by locali zed radiative cooling at numerous sites distributed throughout the flows, d isks of cooled gas do not form and the X-ray images appear nearly circular. Even in this case, however, the spatial distribution of the cooled gas and any young stars that may have formed from this gas would be decidedly flat ter than the old stellar population; if the young stars are optically lumin ous, the Balmer lines they contribute to the stellar spectra should be more elliptical than the total stellar light. In principle, X-ray images of gal actic cooling flows can also be circularized by the turbulent diffusion of angular momentum away from the axis of rotation. But the effective turbulen t viscosity of known processes-stellar mass loss, supernovae, cooling site evolution, etc.-is insufficient to circularize the X-ray images appreciably . Radial gradients in the interstellar iron abundance in elliptical galaxie s similar to those observed are unaffected by the expected level of interst ellar turbulence since these gradients are quickly reestablished by Type Ia supernovae.