Strong-field QED effects on polarization states in dipole and quadrudipole pulsar emissions

TL;DR

This paper studies how quantum electrodynamics effects in highly magnetized neutron stars influence the polarization states of pulsar emissions, revealing distinct evolution patterns depending on magnetic field strength and emission frequency.

Contribution

It introduces a detailed analysis of polarization evolution in pulsar emissions considering quantum refraction effects and provides analytical solutions to the evolution equations.

Findings

Polarization evolution exhibits three main patterns: monotonic, half-oscillatory, and highly oscillatory.

The behavior depends on magnetic field strength and emission frequency.

Analytical solutions confirm the numerical evolution patterns.

Abstract

Highly magnetized neutron stars have quantum refraction effects on pulsar emission due to the non-linearity of the quantum electrodynamics (QED) action. In this paper, we investigate the evolution of the polarization states of pulsar emission under the quantum refraction effects, combined with the dependence on the emission frequency; we solve a system of evolution equations of the Stokes vector, where the birefringent vector, in which such effects are encoded, acts on the Stokes vector. At a fixed frequency of emission, depending on the magnitude of the birefringent vector, dominated mostly by the magnetic field strength, the evolution of the Stokes vector largely exhibits three different patterns: (i) monotonic, or (ii) half-oscillatory, or (iii) highly oscillatory behaviors. These features are understood and confirmed by means of approximate analytical solutions to the evolution equations.