Alignment and Precession of a Black Hole with a Warped Accretion Disc

Understand

We consider the shape of an accretion disc whose outer regions are misaligned with the spin axis of a central black hole and calculate the steady state form of the warped disc in the case where the viscosity and surface densities are power laws in the distance from the central black hole.

• We discuss the shape of the resulting disc in both the frame of the black hole and that of the outer disc.
• We note that some parts of the disc and also any companion star maybe shadowed from the central regions by the warp.
• We compute the torque on the black hole caused by the Lense-Thirring precession and hence compute the alignment and precession timescales.