Warp propagation in astrophysical discs

TL;DR

This paper reviews the physics of warped astrophysical discs, which are common in various cosmic systems, and discusses how they respond to non-axisymmetric forces like black hole precession or gravitational pulls.

Contribution

It provides a comprehensive overview of the fundamental physics governing warped discs and explores their implications across different astrophysical contexts.

Findings

Warped discs are prevalent in many astrophysical systems.

Non-axisymmetric forces induce warping in discs.

The response of discs to warping varies across different systems.

Abstract

Astrophysical discs are often warped, that is, their orbital planes change with radius. This occurs whenever there is a non-axisymmetric force acting on the disc, for example the Lense-Thirring precession induced by a misaligned spinning black hole, or the gravitational pull of a misaligned companion. Such misalignments appear to be generic in astrophysics. The wide range of systems that can harbour warped discs - protostars, X-ray binaries, tidal disruption events, quasars and others - allows for a rich variety in the disc's response. Here we review the basic physics of warped discs and its implications.