Time-dependent global simulations of a thin accretion disc: the effects of magnetically-driven winds on thermal instability

TL;DR

This paper uses global simulations to investigate how magnetically driven winds influence the thermal stability of thin accretion discs, showing winds can suppress instability depending on their strength and mass outflow rate.

Contribution

It introduces a one-dimensional global simulation approach to study the impact of magnetically driven winds on thermal instability in thin accretion discs, highlighting their stabilizing effects.

Findings

Winds transfer angular momentum and cool the disc.

Low wind mass outflow shortens outburst periods.

High wind mass outflow can suppress thermal instability.

Abstract

According to the standard thin disc theory, it is predicted that the radiation-pressure-dominated inner region of a thin disc is thermally unstable, while observations suggest that it is common for a thin disc of more than 0.01 Eddington luminosity to be in a thermally stable state. Previous studies have suggested that magnetically driven winds have the potential to suppress instability. In this work, we implement one-dimensional global simulations of the thin accretion disc to study the effects of magnetically driven winds on thermal instability. The winds play a role in transferring the angular momentum of the disc and cooling the disc. When the mass outflow rate of winds is low, the important role of winds is to transfer the angular momentum and then shorten the outburst period. When the winds have a high mass outflow rate, they can calm down the thermal instability. We also explore the parameter space of the magnetic field strength and the mass loading parameter.