A new constraint on mean-field galactic dynamo theory

Abstract

Appealing to an analytical result from mean-field theory, we show, using a generic galaxy model, that galactic dynamo action can be suppressed by small-scale magnetic fluctuations. This is caused by the magnetic analogue of the Rädler or $\Omega \times J$ effect, where rotation-induced corrections to the mean-field turbulent transport result in what we interpret to be an effective reduction of the standard $\alpha$ effect in the presence of small-scale magnetic fields.

6 pages, 2 figures, 1 table, edited to match MNRAS version

References in corpus (19)

• Simulations of nonhelical hydromagnetic turbulence
• Mean-field concept and direct numerical simulations of rotating magnetoconvection and the geodynamo
• Magnetism in the spiral galaxy NGC 6946: magnetic arms, depolarization rings, dynamo modes and helical fields
• Current status of turbulent dynamo theory: From large-scale to small-scale dynamos
• Direct simulations of a supernova-driven galactic dynamo
• Galactic dynamo and helicity losses through fountain flow
• Kinematic alpha effect in isotropic turbulence simulations
• The Turbulent Dynamo in Highly Compressible Supersonic Plasmas
• Minimal tau approximation and simulations of the alpha effect
• The supernova-regulated ISM. II. The mean magnetic field
• Fluctuation dynamos and their Faraday rotation signatures
• Magnetic fields in the nearby spiral galaxy IC 342: A multi-frequency radio polarization study
• Dynamo coefficients from local simulations of the turbulent ISM
• Non-linear galactic dynamos: A toolbox
• Traces of large-scale dynamo action in the kinematic stage
• A comparison between grid and particle methods on the small-scale dynamo in magnetised supersonic turbulence
• Simulations of the anisotropic kinetic and magnetic alpha effects
• Stellar dynamos with $\vec{\Omega }\times \vec{J}$ effect
• Enhancement of small-scale turbulent dynamo by large-scale shear

Cited by in corpus (5)

• Transition from small-scale to large-scale dynamo in a supernova-driven, multiphase medium
• Non-linear Galactic Dynamos and the Magnetic Rädler Effect
• On the shear-current effect: toward understanding why theories and simulations have mutually and separately conflicted
• Mean field dynamo action in shear flows. I: fixed kinetic helicity
• Synthesizing Observations and Theory to Understand Galactic Magnetic Fields: Progress and Challenges