Properties of magneto-dipole X-ray lines in different radiation models

TL;DR

This paper compares the polarization characteristics of cyclotron and relativistic dipole X-ray emissions from electrons in magnetic fields, proposing observational tests to distinguish their origins in neutron star accretion scenarios.

Contribution

It introduces a polarization-based method to differentiate between cyclotron and relativistic dipole radiation models in X-ray spectra of neutron stars.

Findings

Polarization properties differ significantly between the two radiation models.

A proposed observational test can identify the dominant radiation mechanism.

Application to sources like Her X-1 can clarify the nature of observed spectral features.

Abstract

We compare polarization properties of the cyclotron, and relativistic dipole radiation of electrons moving in the magnetic field on a helix with ultra-relativistic longitudinal and non-relativistic transverse velocity components. The applicability of these models in the case of accretion onto a neutron star is discussed. The test, based on polarization observations is suggested, to distinguish between the cyclotron, and relativistic dipole origin of features, observed in X-ray spectra of some X-ray sources, among which the Her X-1 is the most famous.