Importance of magnetic fields in highly eccentric discs with applications to tidal disruption events

TL;DR

This paper investigates how magnetic fields influence the dynamics of highly eccentric accretion discs in tidal disruption events, showing that magnetic fields can stabilize and significantly alter disc behaviour.

Contribution

It introduces alternative stress models motivated by magnetic field behaviour, demonstrating the importance of magnetic fields in the evolution of TDE discs.

Findings

Magnetic fields have a stabilising effect on eccentric disc dynamics.

Magnetic fields can significantly alter the behaviour of radiation-dominated discs.

Magnetic fields are crucial for the evolution of TDE discs.

Abstract

Whether tidal disruption events (TDEs) circularise or accrete directly as a highly eccentric disc is the subject of current research and appears to depend sensitively on the disc thermodynamics. In a previous paper we applied the theory of eccentric discs to TDE discs using an $\alpha-$prescription for the disc stress, which leads to solutions that exhibit extreme, potentially unphysical, behaviour. In this paper we further explore the dynamical vertical structure of highly eccentric discs using alternative stress models that are better motivated by the behaviour of magnetic fields in eccentric discs. We find that the presence of a coherent magnetic field has a stabilising effect on the dynamics and can significantly alter the behaviour of highly eccentric radiation dominated discs. We conclude that magnetic fields are important for the evolution of TDE discs.