Emission from a Pulsar Wind Nebula: Application to the Persistent Radio Counterpart of FRB 121102

TL;DR

This paper models the persistent radio counterpart of FRB 121102 as a pulsar wind nebula powered by a magnetar, explaining its spectrum, size, and rotation measure without requiring supernova ejecta.

Contribution

It introduces a novel model linking the radio counterpart of FRB 121102 to a magnetar-powered pulsar wind nebula with a stratified medium, constrained by observational data.

Findings

The model explains the spectrum and size of the radio counterpart.

The rotation measure decrease is consistent with the nebula scenario.

Dispersion measure aligns with the shocked medium hypothesis.

Abstract

The properties of fast radio bursts (FRBs) indicate that the physical origin of this type of astrophysical phenomenon is related to neutron stars. The first detected repeating source, FRB 121102, is associated with a persistent radio counterpart. In this paper, we propose that this radio counterpart could arise from a pulsar wind nebula powered by a magnetar without surrounding supernova ejecta. Its medium is a stratified structure produced by a progenitor wind. The model parameters are constrained by the spectrum of the counterpart emission, the size of the nebula, and the large but decreasing rotation measure (RM) of the repeating bursts. In addition, the observed dispersion measure is consistent with the assumption that all of the RM comes from the shocked medium.