Accretion Discs in AGN, Viscosity and Structure of Accretion Disks

Abstract

Early, it has been suggested that Keplerian flows should be unstable regarding shear instabilities. This hypothesis, not seriously considered nowadays, is strongly sustained by a recent re-analysis of experimental data on shear flows and new laboratory experiments. We review some consequences on steady state accretion dises of a viscosity law derived from shear experiments. In particular, we show that it wholly suppresses the thermal and viscous instabilities within the radiation pressure dominated region, unlike the standard theory.