FRB 190520B -- A FRB in a Supernova Remnant?

TL;DR

This paper discusses FRB 190520B, a repeating fast radio burst with a large, variable dispersion measure excess likely caused by a young supernova remnant, and proposes using baseband data to measure high rotation measures.

Contribution

It introduces the idea that the dispersion measure excess in FRB 190520B is due to a young supernova remnant and suggests a method to measure large rotation measures using baseband data.

Findings

Dispersion measure excess varies on a 30-year timescale.

The excess is likely due to a supernova remnant a few decades old.

Magnetic field in the remnant could be around 1 Gauss.

Abstract

FRB 190520B, a repeating FRB near-twin of FRB 121102, was discovered \citep{N21} to have a dispersion measure excess over the intergalactic and Galactic contributions of about 900 pc-cm$^{-3}$, attributable to its host galaxy or near-source environment. This excess varies on a time scale of $\sim 30\,$y and might be explained by a supernova remnant no more than a few decades old. A magnetic field in equipartition with the remnant's expansion would be ${\cal O}(1\,\text{G})$. I suggest the use of baseband data to measure very large rotation measures.