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Magnetic inhibition of centrifugal instability.

Komissarov, Serguei S. and Gourgouliatos, Konstantinos N. and Matsumoto, Jin (2019) 'Magnetic inhibition of centrifugal instability.', Monthly notices of the Royal Astronomical Society., 488 (3). pp. 4061-4073.


Recently, it was shown that the centrifugal instability may be important in the dynamics of astrophysical jets undergoing reconfinement by external pressure. However, these studies were limited to the case of unmagnetized flows. Here, we explore the role of the magnetic field within both the Newtonian and relativistic frameworks. Since the jet problem is rather complicated, we focus instead on the simpler problem of cylindrical rotation and axial magnetic field, which shares significant similarity with the jet problem, and consider only axisymmetric perturbations. The studied equilibrium configurations involve a cylindrical interface and they are stable to non-magnetic centrifugal and magnetorotational instabilities everywhere except this interface. We use a heuristic approach to derive the local stability criterion for the interface in the magnetic case and numerical simulations to verify the role of the magnetic field. The theory and simulations agree quite well for Newtonian models but indicate a potential discrepancy for the relativistic models in the limit of high Lorentz factor of the rotational motion at the interface. In general, the magnetic field sets a critical wavelength below which the centrifugal modes are stabilized. We discuss the implication of our findings for the astrophysical jets, which suggest that the centrifugal instability develops only in jets with relatively low magnetization. Namely, the magnetic pressure has to be below the thermal one and for the relativistic case the jets have to be kinetic-energy dominated.

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Publisher statement:This article has been accepted for publication in the Monthly notices of the Royal Astronomical Society ©: 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:12 July 2019
Date deposited:08 October 2019
Date of first online publication:22 July 2019
Date first made open access:08 October 2019

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