Alfven seismic vibrations of crustal solid-state plasma in quaking paramagnetic neutron star

TL;DR

This paper develops a magneto-solid-mechanical model of crustal vibrations in quaking paramagnetic neutron stars, deriving spectral formulas for oscillation frequencies and lifetimes, and linking them to observed X-ray flux oscillations.

Contribution

It introduces a novel theoretical model for crustal Alfven seismic vibrations in neutron stars, connecting magnetic and elastic forces to observed oscillation spectra.

Findings

Derived analytic spectral formulas for torsional mode frequencies and lifetimes.

Linked observed X-ray oscillations to crustal Alfven seismic vibrations.

Suggested magnetic stresses drive the observed quasi-periodic oscillations.

Abstract

Magneto-solid-mechanical model of two-component, core-crust, paramagnetic neutron star responding to quake-induced perturbation by differentially rotational, torsional, oscillations of crustal electron-nuclear solid-state plasma about axis of magnetic field frozen in the immobile paramagnetic core is developed. Particular attention is given to the node-free torsional crust-against-core vibrations under combined action of Lorentz magnetic and Hooke's elastic forces; the damping is attributed to Newtonian force of shear viscose stresses in crustal solid-state plasma. The spectral formulae for the frequency and lifetime of this toroidal mode are derived in analytic form and discussed in the context of quasi-periodic oscillations of the X-ray outburst flux from quaking magnetars. The application of obtained theoretical spectra to modal analysis of available data on frequencies of oscillating outburst emission suggests that detected variability is the manifestation of crustal Alfven's seismic vibrations restored by Lorentz force of magnetic field stresses.