Accretion Rates onto Massive Black Holes in Four Quiescent Elliptical Galaxies

Four quiescent elliptical galaxies were imaged with the NRAO VLA at 8.5 GHz. Within the context of canonical advection-dominated accretion flows (ADAFs), these VLA images plus published black hole masses constrain the accretion rates to be less than 1.6x10-4, less than 3.6x10-4,