Magnetorotational instability in magnetic diffusion dominated accretion discs

Abstract

We investigate the stability of partially ionised, differentially rotating, diffusive disc threaded by both azimuthal and vertical magnetic field. The general stability criterion of such a disc in the presence of axisymmetric fluctuations can be stated purely in terms of ambipolar and Hall diffusivities. It is shown that the disc is magnetorotationally unstable if the sum of scaled ambipolar and Hall diffusivities are larger than some numerical constant determined by the rotation profile of the disc. This criterion suggests that the diffusive discs are always unstable to almost radial fluctuations. The field geometry and obliqueness of wavevector (encapsulated together in the topological factor $g$), plays dual role of not only assisting MRI in ambipolar--Ohm dominated disc but also making otherwise stable region in Hall--ambipolar diffusion plane unstable.

abstract modified, figures 4 and 5 slightly corrected; discussion modified; accepted MNRAS

References in corpus (11)

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Cited by in corpus (10)

• Wind-driven Accretion in Protoplanetary Disks. I: Suppression of the Magnetorotational Instability and Launching of the Magnetocentrifugal Wind
• Hall-effect Controlled Gas Dynamics in Protoplanetary Disks: II. Full 3D Simulations toward the Outer Disk
• Magnetically driven accretion in protoplanetary discs
• Global Three-Dimensional Simulations of Outer Protoplanetary Disks with Ambipolar Diffusion
• Origin of Weak Turbulence in the Outer Regions of Protoplanetary Disks
• The vertical shear instability in poorly ionised, magnetized protoplanetary discs
• Magnetic diffusion driven shear instability of solar flux tubes
• Growth of Magnetorotational Instability in Circumstellar Disks around Class 0 Protostars
• The impact of resistivity on the variability of black hole accretion flows
• Radially Magnetized Protoplanetary Disk: Vertical Profile