Circular polarization of fast radio bursts in the curvature radiation scenario

TL;DR

This paper proposes that curvature radiation can explain the observed circular polarization in fast radio bursts, linking polarization properties to neutron star characteristics and radiation beam effects.

Contribution

It introduces a curvature radiation model for FRB polarization, explaining circular polarization and position angle swings without relying solely on geometric models.

Findings

Curvature radiation can produce significant circular polarization at the beam's wing.

Higher electron Lorentz factors and more energetic bursts enhance circular polarization.

Neutron star rotation period influences the polarization characteristics.

Abstract

The curvature radiation is applied to the explain the circular polarization of FRBs. Significant circular polarization is reported in both apparently non-repeating and repeating FRBs. Curvature radiation can produce significant circular polarization at the wing of the radiation beam. In the curvature radiation scenario, in order to see significant circular polarization in FRBs (1) more energetic bursts, (2) burst with electrons having higher Lorentz factor, (3) a slowly rotating neutron star at the centre are required. Different rotational period of the central neutron star may explain why some FRBs have high circular polarization, while others don't. Considering possible difference in refractive index for the parallel and perpendicular component of electric field, the position angle may change rapidly over the narrow pulse window of the radiation beam. The position angle swing in FRBs may also be explained by this non-geometric origin, besides that of the rotating vector model.