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In accretion disks with large-scale ordered magnetic fields, the magnetorotational instability (MRI) is marginally suppressed, so other processes may drive angular momentum transport leading to accretion. Accretion could then be driven by…

High Energy Astrophysical Phenomena · Physics 2018-05-16 Megan D. Marshall , Mark J. Avara , Jonathan C. McKinney

The magnetorotational instability (MRI) has been suggested to have an important role on the dynamics of accretion disks. We investigate MRI as an alternative way for guiding the plasma from the disk to the funnel flow at the…

High Energy Astrophysical Phenomena · Physics 2012-10-08 S. Dogan , E. R. Pekunlu

We present an instability occurring in the inner part of disks threaded by a moderately strong vertical (poloidal) magnetic field. Its mechanism is such that a spiral density wave in the disk, driven by magnetic stresses (rather than…

Astrophysics · Physics 2007-05-23 M. Tagger , R. Pellat

Angular momentum transport and particle acceleration during the magnetorotational instability (MRI) in a collisionless accretion disk are investigated using three-dimensional particle-in-cell (PIC) simulation. We show that the kinetic MRI…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Masahiro Hoshino

Magnetorotational Instability (MRI), the instability causing turbulent transport in accretion disks, is studied in the kinetic regime. Radiatively Inefficient Accretion Flows (RIAFs), like the one around the supermassive black hole in the…

Astrophysics · Physics 2007-05-23 Prateek Sharma

Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on…

Earth and Planetary Astrophysics · Physics 2015-06-15 Russell Landry , Sarah E. Dodson-Robinson , Neal J. Turner , Greg Abram

We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionised, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards…

Astrophysics · Physics 2009-11-10 Raquel Salmeron , Mark Wardle

The stresses produced by magnetorotational turbulence can provide effective angular momentum transport in accretion disks. However, questions remain about the ability of simulated disks to reproduce observationally inferred…

High Energy Astrophysical Phenomena · Physics 2015-06-19 E. R. Parkin

We examine the properties of strongly magnetized accretion discs in a global framework, with particular focus on the evolution of magnetohydrodynamic instabilities such as the magnetorotational instability (MRI). Work by Pessah and Psaltis…

High Energy Astrophysical Phenomena · Physics 2017-11-13 Upasana Das , Mitchell C. Begelman , Geoffroy Lesur

Magnetorotational instability (MRI) has a potential to generate the vigorous turbulence in protoplanetary disks, although its turbulence strength and accretion stress remains debatable because of the uncertainty of MRI with low ionization…

Earth and Planetary Astrophysics · Physics 2017-11-15 Shoji Mori , Takayuki Muranushi , Satoshi Okuzumi , Shu-ichiro Inutsuka

Magnetohydrodynamic accretion disk simulations suggest that much of the energy liberated by the magnetorotational instability (MRI) can be channeled into large-scale toroidal magnetic fields through dynamo action. Under certain conditions,…

High Energy Astrophysical Phenomena · Physics 2015-08-19 Mitchell C. Begelman , Philip J. Armitage , Christopher S. Reynolds

The gas dynamics in protoplanetary disks (PPDs) is strongly affected by non-ideal MHD effects. Using a complex chemical reaction network with standard prescriptions for X-ray and cosmic-ray ionizations, as well as the most up-to-date…

Earth and Planetary Astrophysics · Physics 2015-05-28 Xue-Ning Bai

Although the magnetorotational instability (MRI) has been widely accepted as a powerful accretion mechanism in magnetized accretion disks, it has not been realized in the laboratory. The possibility of studying MRI in a rotating…

Astrophysics · Physics 2009-11-06 Hantao Ji , Jeremy Goodman , Akira Kageyama

We study the dynamics of toroidal magnetic flux tubes, symmetric about the rotation axis, inside non-magnetic thick accretion disks around black holes. We present model equations which include effects of gravity, centrifugal force, pressure…

Astrophysics · Physics 2009-10-22 Sandip K. Chakrabarti , Sydney D'Silva

Though usually treated in isolation, the magnetorotational and gravitational instabilities (MRI and GI) may coincide at certain radii and evolutionary stages of protoplanetary discs and active galactic nuclei. Their mutual interactions…

High Energy Astrophysical Phenomena · Physics 2017-12-27 A. Riols , H. Latter

The saturation level of the magneto-rotational instability (MRI) in a strongly radiation dominated accretion disk is studied using a new Godunov radiation MHD code in the unstratified shearing box approximation. Since vertical gravity is…

High Energy Astrophysical Phenomena · Physics 2013-04-09 Yan-Fei Jiang , James M. Stone , Shane W. Davis

How do T Tauri disks accrete? The magneto-rotational instability (MRI) supplies one means, but protoplanetary disk gas is typically too poorly ionized to be magnetically active. Here we show that the MRI can, in fact, explain observed…

Astrophysics · Physics 2015-05-13 Eugene I. Chiang , Ruth A. Murray-Clay

The magnetorotational instability (MRI) can destabilize hydrodynamically stable rotational flows, thereby allowing angular momentum transport in accretion disks. A notorious problem for MRI is its questionable applicability in regions with…

Solar and Stellar Astrophysics · Physics 2013-08-09 Oleg N. Kirillov , Frank Stefani

The magneto-rotational decay instability (MRDI) of thin Keplerian discs threaded by poloidal magnetic fields is introduced and studied. The linear magnetohydrodynamic problem decouples into eigenvalue problems for in-plane slow- and fast-…

Plasma Physics · Physics 2014-03-05 Yuri M. Shtemler , Michael Mond , Edward Liverts

The effect of magnetic field diffusion on the stability of accretion disks is a problem that has attracted considerable interest of late. In particular, the Hall effect has the potential to bring about remarkable changes in the dynamical…

Earth and Planetary Astrophysics · Physics 2017-03-29 Gopakumar Mohandas , Martin E. Pessah