Vertical structure of accretion discs with hot coronae in active galactic nuclei

We study the vertical structure of a radiation-pressure-dominated disc with a hot corona. We include all the relevant processes like bound-free opacit y and convection. We show that the presence of the corona modifies consider ably the density and the opacity of the disc surface layers, which are impo rtant 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 d isc. Such a disc is likely to produce a neutral reflection and a local spec trum close to a blackbody. This effect will help to reconcile the predictio ns of accretion disc models with the observational data since a neutral ref lection and a lack of Lyman edge are generally seen in active galactic nucl ei.