On how much X-ray and UV radiation processes are coupled in accretion disks: AGN case

Abstract

Within the standard accretion disk theory for active galactic nuclei (AGN), the observed X-rays are often modeled by Compton up-scattering of ultraviolet (UV) disk photons inside a hot disk corona. Here, we point out that for many AGN, radiation pressure due to the very same UV disk photons can drive a flow from the disk into the corona and couple the processes producing X-rays and UV photons. This coupling could lead to quenching of the disk corona because the regions above the UV disk will be too dense, too opaque, and consequently too cold. We discuss various consequences of this new type of the X-ray/UV coupling on the dynamical and radiative properties of AGN.