FRB 200428: an Impact between an Asteroid and a Magnetar

TL;DR

This paper proposes that an asteroid impacting a magnetar can produce the observed fast radio burst and associated X-ray emission, offering a new explanation for such phenomena with testable predictions.

Contribution

It introduces a novel asteroid-magnetar impact model to explain FRB 200428, linking asteroid disruption and accretion processes to observed emissions.

Findings

Asteroid of 10^{20} g disrupts near the magnetar

Accreted material produces X-ray burst and FRB

Predicts quasi-periodic oscillations in X-ray burst

Abstract

A fast radio burst (FRB) was recently detected to be associated with a hard X-ray burst from the Galactic magnetar SGR 1935+2154. Scenarios involving magnetars for FRBs are hence highly favored. In this work, we suggest that the impact between an asteroid and a magnetar could explain such a detection. According to our calculations, an asteroid of mass $10^{20}$ g will be disrupted at a distance of $7 \times 10^9$ cm when approaching the magnetar. The accreted material will flow along the magnetic field lines from the Alfv\'en radius $\sim 10^7$ cm. After falling onto the magnetar's surface, an instant accretion column will be formed, producing a Comptonized X-ray burst and an FRB in the magnetosphere. We show that all the observational features of FRB 200428 could be interpreted self-consistently in this scenario. We predict quasi-periodic oscillations in this specific X-ray burst, which can serve as an independent observational test.