Magnetohydrodynamic stability of magnetars in the ultrastrong field regime II: The crust

Abstract

We study the stability of Hall MHD with strong magnetic fields in which Landau quantization of electrons is important. We find that the strong-field Hall modes can be destabilized by the dependence of the differential magnetic susceptibility on magnetic field strength. This instability is studied using linear perturbation theory, and is found to have typical growth time of order $\lesssim 10^3$ yrs, with the growth time decreasing as a function of wavelength of the perturbation. The instability is self-limiting, turning off following a period of local field growth by a few percent of the initial value. Finite temperature is also shown to limit the instability, with sufficiently high temperatures eliminating it altogether. Alfvén waves can show similar unstable behaviour on shorter timescales. We find that Ohmic heating due to the large fields developed via the instability and magnetic domain formation is not large enough to account for observed magnetar surface temperatures. However, Ohmic heating is enhanced by the oscillatory differential magnetic susceptibility of Landau-quantized electrons, which could be important to magneto-thermal simulations of neutron star crusts.

20 pages, 18 figures

References in corpus (14)

• Physics of Strongly Magnetized Neutron Stars
• Fast radio bursts as synchrotron maser emission from decelerating relativistic blast waves
• The Breaking Strain of Neutron Star Crust and Gravitational Waves
• Magnetars: Properties, Origin and Evolution
• Hall drift and the braking indices of young pulsars
• Thermoplastic waves in magnetars
• Magnetic-field evolution in a plastically-failing neutron-star crust
• Magnetars as cooling neutron stars with internal heating
• Entrainment in Superfluid Neutron Star Crusts: Hydrodynamic Description and Microscopic Origin
• Magnetar activity mediated by plastic deformations of neutron star crust
• Density-shear instability in electron MHD
• Lagrangian perturbation theory for rotating magnetic stars
• Heating in Magnetar Crusts from Electron Captures
• Magnetohydrodynamic stability of magnetars in the ultrastrong field regime I: The core

Cited by in corpus (3)

• Magnetar structure in non-linear electrodynamics with mixed poloidal-toroidal fields
• Topology of the Superconducting Heart of Neutron Stars: Effects of Microphysics and Gravitational-Wave Signatures
• Numerical simulation of electron magnetohydrodynamics with Landau-quantized electrons in magnetar crusts