Magnetorotational instability in Keplerian disks: a nonlocal approach

N.I. Shakura^†^a, b, K.A. Postnov^‡^a, b, D.A. Kolesnikov^§^a, c, G.V. Lipunova^*^a, d
^aLomonosov Moscow State University, Shternberg State Astronomical Institute, Universitetskii prosp. 13, Moscow, 119889, Russian Federation
^bKazan Federal University, ul. Kremlyovskaya 18, Kazan, 420008, Russian Federation
^cTel-Aviv University, Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv, Israel
^dMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, Bonn, 53121, Germany

We revisit the modal analysis of small perturbations in Keplerian ideal gas flows with a constant vertical magnetic field leading to magnetorotational instability (MRI) using the nonlocal approach. In the general case, MRI modes are described by a Schrödinger-like differential equation with some effective potential, including 'repulsive' (1/r²) and 'attractive' (−1/rr³) terms, and are quantized. In shallow potentials, there are no stationary 'energy levels.' In thin Keplerian accretion discs, the perturbation wavelengths λ =2π /k_z are smaller than the disc semi-thickness h only in 'deep' potential wells. We find that there is a critical magnetic field for the MRI to develop. The instability arises for magnetic fields below this critical value. In thin accretion discs, at low background Alfvén velocity c_A≪ (c_A)_cr, the MRI instability increment ω is suppressed compared to the value obtained in the local perturbation analysis, ω ≈ −√3ic_Ak_z. We also investigate for the first time the case of a radially variable background magnetic field.

Keywords: magnetorotational instability, accretion discs
PACS: 95.30.Qd, 97.10.Gz (all)
DOI: 10.3367/UFNe.2023.09.039554
URL: https://ufn.ru/en/articles/2023/12/f/
Web of Science

001172931200005
Scopus

2-s2.0-85183001473
ADS NASA

2023PhyU...66.1262S
Citation: Shakura N I, Postnov K A, Kolesnikov D A, Lipunova G V "Magnetorotational instability in Keplerian disks: a nonlocal approach" Phys. Usp. 66 1262–1276 (2023)

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RT Journal
T1 Magnetorotational instability in Keplerian disks: a nonlocal approach
A1 Shakura,N.I.
A1 Postnov,K.A.
A1 Kolesnikov,D.A.
A1 Lipunova,G.V.
PB Physics-Uspekhi
PY 2023
FD 10 Dec, 2023
JF Physics-Uspekhi
JO Phys. Usp.
VO 66
IS 12
SP 1262-1276
DO 10.3367/UFNe.2023.09.039554
LK https://ufn.ru/en/articles/2023/12/f/

Received: 16th, December 2022, revised: 21st, September 2023, accepted: 22nd, September 2023

Оригинал: Шакура Н И, Постнов К А, Колесников Д А, Липунова Г В «Магниторотационная неустойчивость в кеплеровских дисках: нелокальный подход» УФН 193 1340–1355 (2023); DOI: 10.3367/UFNr.2023.09.039554