Compressibility and local instabilities of differentially rotating magnetized gas

Abstract

We study the stability of compressible cylindrical differentially rotating flow in the presence of the magnetic field, and show that compressibility alters qualitatively the stability properties of flows. Apart from the well-known magnetorotational instability that can occur even in incompressible flow, there exist a new instability caused by compressibility. The necessary condition of the newly found instability can easily be satisfied in various flows in laboratory and astrophysical conditions and reads $B_s{B}_{\varphi }{\Omega }^{\prime }\ne 0$ where $B_s$ and $B_{\varphi }$ are the radial and azimuthal magnetic fields, ${\Omega }^{\prime }=d\Omega /ds$ with $s$ being the cylindrical radius. Contrary to the magnetorotational instability that occurs only if $\Omega$ decreases with $s$, the newly found instability operates at any sign of ${\Omega }^{\prime }$. The considered instability can arise even in a very strong magnetic field that suppresses the magnetorotational instability.

29 pages, 9 figures, accepted for publication in ApJ

References in corpus (5)

• Magnetically Driven Accretion Flows in the Kerr Metric II: Structure of the Magnetic Field
• The Stability of Magnetized Rotating Plasmas with Superthermal Fields
• Magneto-rotational overstability in accretion disks
• Hydromagnetic Instability in Differentially Rotating Flows
• Convective magneto-rotational instabilities in accretion disks

Cited by in corpus (8)

• Linear stability analysis of magnetized relativistic rotating jets
• Linear stability analysis of magnetized jets: the rotating case
• Stretching of the toroidal field and generation of magnetosonic waves in differentially rotating plasma
• Linear stability of magnetized massive protoplanetary disks
• Magnetic shear-driven instability and turbulent mixing in magnetized protostellar disks
• Current-driven instabilities in weakly ionized disks
• Magnetohydrodynamic instability in differentially rotating compressible flow
• High-growth-rate magnetohydrodynamic instability in differentially rotating compressible flow