Pulsating magneto-dipole radiation of a quaking neutron star powered by energy of Alfven seismic vibrations

TL;DR

This paper models how neutron stars undergoing torsional Alfvén vibrations emit pulsating magneto-dipole radiation powered by their seismic energy, with implications for understanding observed X-ray pulsations.

Contribution

It introduces a theoretical model linking seismic vibrations in neutron stars to their magnetic dipole radiation, including numerical estimates and the effect of magnetic field decay.

Findings

Vibration frequencies decrease over time due to magnetic field decay.

The model explains pulsating high-energy emissions from magnetars.

Predicted radiation characteristics match observed X-ray pulsations.

Abstract

We compute the characteristic parameters of magnetic dipole radiation of a neutron star undergoing torsional seismic vibrations under the action of Lorentz restoring force about axis of a dipolar magnetic field experiencing decay. After brief outline of general theoretical background of the model of vibration powered neutron star, we present numerical estimates of basic vibration and radiation characteristics, such as the oscillation frequency, lifetime, luminosity of radiation, and investigate their time dependence upon magnetic field decay. The presented analysis suggests that gradual decrease in frequencies of pulsating high-energy emission detected from a handful of currently monitored AXP/SGR-like X-ray sources can be explained as being produced by vibration powered magneto-dipole radiation of quaking magnetars. \keywords{neutron stars, torsion Alfv\'en vibrations, vibration powered radiation, magnetic field decay, magnetars}