A unified picture of Galactic and cosmological fast radio bursts

TL;DR

This paper links the Galactic FRB associated with a magnetar to cosmological FRBs, suggesting they are the same class of transients, and proposes a model involving magnetic disturbances near the magnetar surface to explain their emission.

Contribution

It presents evidence that Galactic and cosmological FRBs are likely the same phenomenon and introduces a model involving magnetic disturbances near the magnetar surface for their radio emission.

Findings

Galactic FRB rate matches the faint end of cosmological FRB rate.

Radio and X-ray burst rates suggest 100-1000 X-ray bursts per FRB.

The two-peak radio lightcurve constrains emission models.

Abstract

The discovery of a fast radio burst (FRB) in our galaxy associated with a magnetar (neutron star with strong magnetic field) has provided a critical piece of information to help us finally understand these enigmatic transients. We show that the volumetric rate of Galactic-FRB like events is consistent with the faint end of the cosmological FRB rate, and hence they most likely belong to the same class of transients. The Galactic FRB had an accompanying X-ray burst but many X-ray bursts from the same object had no radio counterpart. Their relative rates suggest that for every FRB there are roughly 10^2 to 10^3 X-ray bursts. The radio lightcurve of the galactic FRB had two spikes separated by 30 ms in the 400-800 MHz frequency band. This is an important clue and highly constraining of the class of models where the radio emission is produced outside the light-cylinder of the magnetar. We suggest that magnetic disturbances close to the magnetar surface propagate to a distance of a few tens of neutron star radii where they damp and produce radio emission. The coincident hard X-ray spikes associated with the two FRB pulses seen in this burst and the flux ratio between the two frequency bands can be understood in this scenario. This model provides a unified picture for faint bursts like the Galactic FRB as well as the bright events seen at cosmological distances.