Magnetic helicity fluxes and their effect on stellar dynamos

TL;DR

This paper investigates how magnetic helicity fluxes influence stellar dynamo processes, demonstrating their role in reducing quenching effects and identifying key parameters for dynamo action through simulations.

Contribution

It introduces a formalism combining diffusive and dynamic quenching mechanisms to study magnetic helicity fluxes in alpha^2 dynamos at high magnetic Reynolds numbers.

Findings

Magnetic helicity fluxes can alleviate catastrophic quenching in dynamos.

Preferred dynamo mode is antisymmetric about the mid-plane.

Results are verified with 3-D direct numerical simulations.

Abstract

Magnetic helicity fluxes in turbulently driven alpha^2 dynamos are studied to demonstrate their ability to alleviate catastrophic quenching. A one-dimensional mean-field formalism is used to achieve magnetic Reynolds numbers of the order of 10^5. We study both diffusive magnetic helicity fluxes through the mid-plane as well as those resulting from the recently proposed alternate dynamic quenching formalism. By adding shear we make a parameter scan for the critical values of the shear and forcing parameters for which dynamo action occurs. For this $\alpha\Omega$ dynamo we find that the preferred mode is antisymmetric about the mid-plane. This is also verified in 3-D direct numerical simulations.