Magnetic self-organization in Hall-dominated magnetorotational turbulence

2013/06/25 by Matthew W. Kunz, Geoffroy Lesur · 145 citations
Physics and Astronomy · #Accretion (finance) #Angular momentum #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Classical mechanics #Instability #Magnetic field #Magnetohydrodynamic drive #Magnetohydrodynamics #Magnetorotational instability #Mechanics #Physics #Stellar, planetary, and galactic studies #Turbulence #astro-ph.EP #astro-ph.SR #physics.flu-dyn

paper · pdf · doi:10.1093/mnras/stt1171

published in Monthly Notices of the Royal Astronomical Society 434(3), 2295-2312 (Oxford University Press) · 18 pages, 16 figures, accepted for publication in MNRAS

arxiv created 2013/06/25 · openalex publication_date 2013/07/27 · arxiv updated 2015/06/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

The magnetorotational instability (MRI) is the most promising mechanism by which angular momentum is efficiently transported outwards in astrophysical discs. However, its application to protoplanetary discs remains problematic. These discs are so poorly ionized that they may not support magnetorotational turbulence in regions referred to as ‘dead zones’. It has recently been suggested that the Hall effect, a non-ideal magnetohydrodynamic (MHD) effect, could revive these dead zones by enhancing the magnetically active column density by an order of magnitude or more. We investigate this idea by performing local, three-dimensional, resistive Hall-MHD simulations of the MRI in situations where the Hall effect dominates over Ohmic dissipation. As expected from linear stability analysis, we find an exponentially growing instability in regimes otherwise linearly stable in resistive MHD. However, instead of vigorous and sustained magnetorotational turbulence, we find that the MRI saturates by producing large-scale, long-lived, axisymmetric structures in the magnetic and velocity fields. We refer to these structures as zonal fields and zonal flows, respectively. Their emergence causes a steep reduction in turbulent transport by at least two orders of magnitude from extrapolations based upon resistive MHD, a result that calls into question contemporary models of layered accretion. We construct a rigorous mean-field theory to explain this new behaviour and to predict when it should occur. Implications for protoplanetary disc structure and evolution, as well as for theories of planet formation, are briefly discussed.

Citations

• On the Magnetic Prandtl Number Behavior of Accretion Disks
• THE TURBULENT MAGNETIC PRANDTL NUMBER OF MHD TURBULENCE IN DISKS
• EFFECT OF AMBIPOLAR DIFFUSION ON THE NONLINEAR EVOLUTION OF MAGNETOROTATIONAL INSTABILITY IN WEAKLY IONIZED DISKS
• Ambipolar diffusion in the magnetorotational instability
• A powerful local shear instability in weakly magnetized disks. I - Linear analysis. II - Nonlinear evolution
• Hydrodynamic stability of rotationally supported flows: Linear and nonlinear 2D shearing box results
• The Balbus-Hawley instability in weakly ionized discs

Cited by

• exoALMA. XVI. Predicting Signatures of Large-scale Turbulence in Protoplanetary Disks
• HALL EFFECT CONTROLLED GAS DYNAMICS IN PROTOPLANETARY DISKS. II. FULL 3D SIMULATIONS TOWARD THE OUTER DISK
• MAGNETIC FLUX CONCENTRATION AND ZONAL FLOWS IN MAGNETOROTATIONAL INSTABILITY TURBULENCE
• Thanatology in protoplanetary discs
• FUV Irradiation and the Heat Signature of Accretion in Protoplanetary Disk Atmospheres
• Global multifluid simulations of the magnetorotational instability in radially stratified protoplanetary discs

Related

• Thanatology in protoplanetary discs
• Magnetorotational Instability in a Swirling Partially Ionized Gas
• Global magnetohydrodynamic simulations of the inner regions of protoplanetary discs. I. Zero-net flux regime
• Dust Dynamics in Hall-effected Protoplanetary Disks. I. Background Drift Hall Instability
• Trapping solids at the inner edge of the dead zone: 3-D global MHD simulations