Self-induced warping of accretion discs: non-linear evolution and application to AGN

In a recent paper it was shown that an accretion disc which is irradiated by a central source of radiation can be unstable to becoming warped. In this paper we investigate the growth and non-linear evolution of such radiation-induced warps, taking self-shadowing by the disc fully into account. We apply the results to accretion discs around massive black holes such as are thought to exist in active galactic nuclei. We show that for most of the time the disc configuration is such that the central radiation source is visible only from within two cones of semi-opening angle ∼30° at a variable orientation to the outer disc. Furthermore, if jets emanate from the inner disc perpendicular to the local surface, then the calculations indicate that the axis of the jets and the normal to the outer disc are usually severely misaligned.