On the magnetic quenching of mean-field effects in supersonic interstellar turbulence

Abstract

The emergence of large-scale magnetic fields observed in the diffuse interstellar medium is explained by a turbulent dynamo. The underlying transport coefficients have previously been extracted from numerical simulations. So far, this was restricted to the kinematic regime, but we aim to extend our analysis into the realm of dynamically important fields. This marks an important step on which derived mean-field models rely to explain observed equipartition strength fields. As in previous work, we diagnose turbulent transport coefficients by means of the test-field method. We derive quenching functions for the dynamo α effect, diamagnetic pumping, and turbulent diffusivity, which are compared with theoretical expectations. At late times, we observe the suppression of the vertical wind. Because this potentially affects the removal of small-scale magnetic helicity, new concerns arise about circumventing constraints imposed by the conservation of magnetic helicity at high magnetic Reynolds numbers. While present results cannot safely rule out this possibility, the issue only becomes important at late stages and is absent when the dynamo is quenched by the wind itself.

5 pages, 6 figures, to be published in MNRAS

References in corpus (8)

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• Direct simulations of a supernova-driven galactic dynamo
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Cited by in corpus (20)

• Dynamo theories
• Galactic Dynamos
• Quenching and anisotropy of hydromagnetic turbulent transport
• Non-linear galactic dynamos: A toolbox
• Dynamo saturation in direct simulations of the multi-phase turbulent interstellar medium
• Toward a hybrid dynamo model for the Milky Way
• Galactic magnetic fields and hierarchical galaxy formation
• The magnetic shear-current effect: generation of large-scale magnetic fields by the small-scale dynamo
• Turbulent transport coefficients in galactic dynamo simulations using singular value decomposition
• Magnetic fields during galaxy mergers
• Statistical tests of galactic dynamo theory
• A Subgrid Turbulent Mean Field Dynamo Model for Cosmological Galaxy Formation Simulations
• The supernova-regulated ISM -- VI. Magnetic effects on the structure of the interstellar medium
• Non-linear Galactic Dynamos and the Magnetic Rädler Effect
• On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence
• A global galactic dynamo with a corona constrained by relative helicity
• Quantifying the effect of turbulent magnetic diffusion on the growth rate of the magneto-rotational instability
• Unified treatment of mean-field dynamo and angular-momentum transport in magnetorotational instability-driven turbulence
• Mean fields and fluctuations in compressible magnetohydrodynamic flows
• On the Combined Role of Cosmic Rays and Supernova-Driven Turbulence for Galactic Dynamos