One-winged butterflies: mode selection for azimuthal magnetorotational instability by thermal convection

A. Mishra, G. Mamatsashvili, M. Seilmayer, F. Stefani

Published 2024-03-14Version 1

The effects of thermal convection on turbulence in accretion discs, and particularly its interaction with the magnetorotational instability (MRI), are of significant astrophysical interest. Despite extensive theoretical and numerical studies, such interactions have not been explored experimentally. We conduct linear analysis of the azimuthal version of MRI (AMRI) in the presence of convection and compare our findings with the experimental data. We show that AMRI sets in at lower critical Hartmann numbers ($Ha$) in the presence of convection. Importantly, convection breaks symmetry between the $m = \pm 1$ modes ($m$ is the azimuthal wavenumber). This preference for one mode over the other makes the AMRI-wave look like a "one-winged butterfly" observed in the experiments.