Generation of magnetic fields by large-scale vortices in rotating convection

TL;DR

This paper introduces a new dynamo mechanism where large-scale vortices in rotating turbulent convection can generate large-scale magnetic fields, especially below the small-scale dynamo threshold.

Contribution

It demonstrates that large-scale vortices in rotating convection can sustain large-scale magnetic fields without requiring small-scale dynamo action, a novel insight into magnetic field generation.

Findings

Large-scale vortices can generate magnetic fields at low magnetic Reynolds numbers.

The mechanism operates below the threshold for small-scale dynamo action.

It provides a new understanding of magnetic field generation in natural rotating systems.

Abstract

We propose a new self-consistent dynamo mechanism for the generation of large-scale magnetic fields in natural objects. Recent computational studies have described the formation of large-scale vortices (LSVs) in rotating turbulent convection. Here we demonstrate that for magnetic Reynolds numbers below the threshold for small-scale dynamo action, such turbulent flows can sustain large-scale magnetic fields --- i.e. fields with a significant component on the scale of the system.