Modeling astrophysical outflows via the unified Dynamo-Reverse Dynamo mechanism

Abstract

The unified Dynamo-Reverse Dynamo (Dy-RDy) mechanism, capable of simultaneously generating large scale outflows and magnetic fields from an ambient microscopic reservoir, is explored in a broad astrophysical context. The Dy-RDy mechanism is derived via Hall magnetohydrodynamics, which unifies the evolution of magnetic field and fluid vorticity. It also introduces an intrinsic length scale, the ion skin depth, allowing for the proper normalization and categorization of microscopic and macroscopic scales. The large scale Alfvén Mach number ${\mathcal{M}}_A$, defining the relative "abundance" of the flow field to the magnetic field is shown to be tied to a microscopic scale length that reflects the characteristics of the ambient short scale reservoir. The dynamo (Dy), preferentially producing the large scale magnetic field, is the dominant mode when the ambient turbulence is mostly kinetic, while the outflow producing reverse dynamo (RDy) is the principal manifestation of a magnetically dominated turbulent reservoir. It is conjectured that an efficient RDy may be the source of many observed astrophysical outflows that have ${\mathcal{M}}_A\gg 1$.

5 pages, 1 table, 1 figure; accepted for publication in MNRAS Letters

References in corpus (5)

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Cited by in corpus (12)

• Extended MHD turbulence and its applications to the solar wind
• On the structure and statistical theory of turbulence of extended magnetohydrodynamics
• Hall current effects in mean-field dynamo theory
• On Beltrami states near black hole event horizon
• Multi-region relaxed magnetohydrodynamics with flow
• Macro-scale fast flow and magnetic field generation in 2-temperature relativistic electron-ion plasmas of astrophysical objects
• Modification of magnetohydrodynamic waves by the relativistic Hall effect
• Multi-region relaxed Hall magnetohydrodynamics with flow
• On the quadruple Beltrami fields in thermally relativistic electron-positron-ion plasma
• Hall MHD waves: A fundamental departure from their MHD counterparts
• Multiscale structures in three species magnetoplasmas with two positive ions
• Dynamical generation of macroscale magnetic fields and fast flows in a four-component astrophysical plasma