Magnetohydrodynamic stability of magnetars in the ultrastrong field regime I: the core

ABSTRACT We study magnetohydrodynamic stability of neutron star core matter composed neutrons, protons, and leptons threaded by a magnetar-strength magnetic field 1014–1017 G, where quantum electrodynamical effects Landau quantization fermions are important. Stability is determined using the Friedman–Schutz formalism for canonical energy fluid perturbations, which we calculate magnetizable with H ≠ B. Using this Euler–Heisenberg–Fermi–Dirac Lagrangian strongly magnetized Landau-quantized charged fermions, local criteria spherical axisymmetric geometry toroidal field, accounting composition gradient buoyancy. find that, sufficiently strong fields B ≳ 1015 unstable to magnetosonic-type instability growth times order 10−3 s. The triggered sharp changes in second-order derivative that occur additional levels start being populated. These divergent at zero temperature, but finite non-zero so realistic temperatures 5 × 107 K < T 108 used. conjecture mechanism could promote formation domains as predicted Blandford Hernquist Suh Mathews.