Vertical Structure of Accretion Discs with Hot Coronae in AGN

Abstract

We study vertical structure of radiation pressure dominated disc with a hot corona. We include all the relevant processes like bound--free opacity and convection. We show that the presence of the corona modifies considerably the density and the opacity of the disc surface layers which are important from the point of view of spectrum formation. The surface of the disc with a corona is much denser and less ionized than the surface of a bare disc. Such a disc is likely to produce a neutral reflection and a local spectrum close to a black body. This effect will help to reconcile the predictions of accretion disc models with the observational data since a neutral reflection and a lack of Lyman edge are generally seen in AGN.