Kinematic Dynamo, Supersymmetry Breaking, and Chaos

TL;DR

This paper explores the mathematical link between the kinematic dynamo and supersymmetric stochastic theory, revealing that dynamo action is tied to chaos and supersymmetry breaking, with implications for understanding astrophysical magnetic fields.

Contribution

It establishes a novel correspondence between the kinematic dynamo and supersymmetric stochastic theory, providing new insights into the role of chaos and supersymmetry breaking in magnetic field growth.

Findings

Dynamo effect corresponds to supersymmetry breaking in STS.

Chaotic flows are necessary for dynamo action, even with diffusion.

Exponential growth and oscillations in KD modes confirm supersymmetry breaking.

Abstract

The kinematic dynamo (KD) describes the growth of magnetic fields generated by the flow of a conducting medium in the limit of vanishing backaction of the fields onto the flow. The KD is therefore an important model system for understanding astrophysical magnetism. Here, the mathematical correspondence between the KD and a specific stochastic differential equation (SDE) viewed from the perspective of the supersymmetric theory of stochastics (STS) is discussed. The STS is a novel, approximation-free framework to investigate SDEs. The correspondence reported here permits insights from the STS to be applied to the theory of KD and vice versa. It was previously known that the fast KD in the idealistic limit of no magnetic diffusion requires chaotic flows. The KD-STS correspondence shows that this is also true for the diffusive KD. From the STS perspective, the KD possesses a topological supersymmetry and the dynamo effect can be viewed as its spontaneous breakdown. This supersymmetry breaking can be regarded as the stochastic generalization of the concept of dynamical chaos. As this supersymmetry breaking happens in both the diffusive and the non-diffusive case, the necessity of the underlying SDE being chaotic is given in either case. The observed exponentially growing and oscillating KD modes prove physically that dynamical spectra of the STS evolution operator that break the topological supersymmetry exist with both, real and complex ground state eigenvalues. Finally, we comment on the non-existence of dynamos for scalar quantities.