On the Papaloizou-Pringle instability in tidal disruption events

TL;DR

This paper investigates how the Papaloizou-Pringle instability affects the evolution of thick accretion disks formed in tidal disruption events, potentially leading to rapid angular momentum redistribution and early mass accretion.

Contribution

It demonstrates that the Papaloizou-Pringle instability can induce significant angular momentum transfer in tidal disruption remnants, influencing early accretion before magnetic instabilities develop.

Findings

The instability can cause rapid angular momentum redistribution.

Accretion rates can be super-Eddington but are short-lived.

The instability may trigger early mass accretion prior to MRI onset.

Abstract

We demonstrate that the compact, thick disc formed in a tidal disruption event may be unstable to non-axisymmetric perturbations in the form of the Papaloizou-Pringle instability. We show this can lead to rapid redistribution of angular momentum that can be parameterised in terms of an effective Shakura-Sunyaev $\alpha$ parameter. For remnants that have initially weak magnetic fields, this may be responsible for driving mass accretion prior to the onset of the magneto-rotational instability. For tidal disruptions around a $10^6$ M$_{\odot}$ black hole, the measured accretion rate is super-Eddington but is not sustainable over many orbits. We thus identify a method by which the torus formed in tidal disruption event may be significantly accreted before the magneto-rotational instability is established.