Self-induced warping of accretion discs

A warped accretion disc with a central radiation source is subject to non-axisymmetric radiation pressure forces, which in turn modify the warp. We show here, with a simple analytic approach, that even an initially flat disc is unstable to warping through this effect. We give estimates of the radii at which such self-induced warping takes place, and discuss applications to discs in binary X-ray sources and in active galactic nuclei.