A self-sustaining nonlinear dynamo process in Keplerian shear flows

TL;DR

This paper identifies a nonlinear dynamo process in Keplerian shear flows, which could explain magnetic field sustenance in accretion disks, by demonstrating a magneto-rotational instability-driven mechanism analogous to hydrodynamic self-sustaining processes.

Contribution

It introduces a new nonlinear dynamo mechanism in Keplerian flows based on magneto-rotational instability, with numerical solutions across various magnetic Reynolds numbers.

Findings

Dynamo process exists in rotating shear flows.

Steady solutions found at low Reynolds numbers.

Potential relevance to accretion disk magnetic fields.

Abstract

A three-dimensional nonlinear dynamo process is identified in rotating plane Couette flow in the Keplerian regime. It is analogous to the hydrodynamic self-sustaining process in non-rotating shear flows and relies on the magneto-rotational instability of a toroidal magnetic field. Steady nonlinear solutions are computed numerically for a wide range of magnetic Reynolds numbers but are restricted to low Reynolds numbers. This process may be important to explain the sustenance of coherent fields and turbulent motions in Keplerian accretion disks, where all its basic ingredients are present.