Hyperflares of SGRs as an engine for millisecond extragalactic radio bursts

TL;DR

This paper suggests that millisecond extragalactic radio bursts could originate from hyperflares of soft gamma-ray repeaters, linking observed radio fluxes to magnetar magnetosphere instabilities.

Contribution

It proposes a novel connection between hyperflares of soft gamma-ray repeaters and millisecond extragalactic radio bursts, supported by estimated flare rates and a proposed emission mechanism.

Findings

Hyperflare rate matches observed radio burst occurrence.

Radio flux can be explained by magnetar magnetosphere tearing mode instability.

Proposed mechanism accounts for observed burst intensity.

Abstract

We propose that the strong millisecond extragalactic radio burst (mERB) discovered by Lorimer et al. (2007) may be related to a hyperflare from an extragalactic soft gamma-ray repeater. The expected rate of such hyperflares, $\sim$ 20 - 100 d$^{-1}$ Gpc$^{-3}$, is in good correspondence with the value estimated by Lorimer et al. The possible mechanism of radio emission can be related to the tearing mode instability in the magnetar magnetosphere as discussed by Lyutikov (2002), and can produce the radio flux corresponding to the observed $\sim$ 30 Jy from the mERB using a simple scaling of the burst energy.