2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/1772We review the origin and structure of hot (cooling flow) gas in elliptical galaxies. X-ray observations can be used to determine the stellar mass to light ratio, the mass profiles of dark matter halos, and the interstellar magnetic field. Interstellar gas cools over a large volume, forming stars with a bottom-heavy IMF. For consistency with the thin fundamental plane, young stars must be optically luminous. Circular X-ray isophotes in rotating elliptical galaxies indicate distributed radiative cooling or strong interstellar turbulence.4 pages; to appear in "Gas and Galaxy Evolution" ASP Conf. Ser. eds. Hibbard, Rupen & van GorkomAstrophysicstext