# Convective Quenching of Field Reversals in Accretion Disc Dynamos

## TL;DR

This study investigates how hydrodynamic convection in accretion disc dynamos suppresses magnetic field reversals, replacing them with quasi-periodic fluctuations, through analysis of stratified shearing box simulations.

## Contribution

It demonstrates that convection prevents magnetic field reversals by mixing magnetic fields, offering new insights into magnetic behavior in accretion disc turbulence.

## Key findings

- Convection suppresses field reversals in simulations.
- Magnetic field fluctuations remain quasi-periodic with fixed polarity.
- Hydrodynamic mixing destroys reversals by transporting magnetic flux.

## Abstract

Vertically stratified shearing box simulations of magnetorotational turbulence commonly exhibit a so-called butterfly diagram of quasi-periodic azimuthal field reversals. However, in the presence of hydrodynamic convection, field reversals no longer occur. Instead, the azimuthal field strength fluctuates quasi-periodically while maintaining the same polarity, which can either be symmetric or antisymmetric about the disc midplane. Using data from the simulations of Hirose et al. (2014), we demonstrate that the lack of field reversals in the presence of convection is due to hydrodynamic mixing of magnetic field from the more strongly magnetized upper layers into the midplane, which then annihilate field reversals that are starting there. Our convective simulations differ in several respects from those reported in previous work by others, in which stronger magnetization likely plays a more important role than convection.