Apsidal precession, disc breaking and viscosity in warped discs

TL;DR

This paper investigates the role of general relativistic apsidal precession in warped black hole accretion discs through 3D simulations, revealing its significant impact on disc evolution and phenomena like disc breaking.

Contribution

It introduces the first comparison of simulations with and without apsidal precession, highlighting its crucial influence on disc dynamics and warp behavior.

Findings

Apsidal precession alters disc evolution significantly.

Moderately inclined discs exhibit oscillating tilt profiles.

Large inclinations lead to disc breaking phenomena.

Abstract

We demonstrate the importance of general relativistic apsidal precession in warped black hole accretion discs by comparing three - dimensional smoothed particle hydrodynamic simulations in which this effect is first neglected, and then included. If apsidal precession is neglected, we confirm the results of an earlier magnetohydrodynamic simulation which made this assumption, showing that at least in this case the $\alpha$ viscosity model produces very similar results to those of simulations where angular momentum transport is due to the magnetorotational instability. Including apsidal precession significantly changes the predicted disc evolution. For moderately inclined discs thick enough that tilt is transported by bending waves, we find a disc tilt which is nonzero at the inner disc edge and oscillates with radius, consistent with published analytic results. For larger inclinations we find disc breaking.