Galactic dynamo and helicity losses through fountain flow

Abstract

Nonlinear behaviour of galactic dynamos is studied, allowing for magnetic helicity removal by the galactic fountain flow. A suitable advection speed is estimated, and a one-dimensional mean-field dynamo model with dynamic alpha-effect is explored. It is shown that the galactic fountain flow is efficient in removing magnetic helicity from galactic discs. This alleviates the constraint on the galactic mean-field dynamo resulting from magnetic helicity conservation and thereby allows the mean magnetic field to saturate at a strength comparable to equipartition with the turbulent kinetic energy.

4 pages, 2 figures, accepted by A&A Letters

References in corpus (3)

• The case for a distributed solar dynamo shaped by near-surface shear
• Minimal tau approximation and simulations of the alpha effect
• Nonlinear current helicity fluxes in turbulent dynamos and alpha quenching

Cited by in corpus (7)

• Galactic dynamos supported by magnetic helicity fluxes
• A Radio and Optical Polarization Study of the Magnetic Field in the Small Magellanic Cloud
• Small-scale magnetic helicity losses from a mean-field dynamo
• Galactic dynamo action in presence of stochastic alpha and shear
• Laboratory Plasma Dynamos, Astrophysical Dynamos, and Magnetic Helicity Evolution
• Toward Coupling Flow Driven and Magnetically Driven Dynamos
• Magnetic helicity in primordial and dynamo scenarios of galaxies