Radio rebrightening of the GRB afterglow by the accompanying supernova

TL;DR

This paper predicts that supernova remnants associated with long-duration gamma-ray bursts will produce a late-time radio rebrightening, outshining the initial GRB afterglow and peaking decades after the explosion, providing insights into shock particle acceleration.

Contribution

It introduces the concept that supernova remnants can cause a late-time radio rebrightening in GRB afterglows, which has not been previously emphasized.

Findings

Supernova remnants will produce a radio emission peak decades after the GRB.

The supernova remnant emission can outshine the GRB afterglow before its peak.

Detection of this emission can improve understanding of particle acceleration in shocks.

Abstract

The gamma-ray burst (GRB) jet powers the afterglow emission by shocking the surrounding medium, and radio afterglow can now be routinely observed to almost a year after the explosion. Long-duration GRBs are accompanied by supernovae (SNe) that typically contain much more energy than the GRB jet. Here we consider the fact that the SN blast wave will also produce its own afterglow (supernova remnant emission), which will peak at much later time (since it is non-relativistic), when the SN blast wave transitions from a coasting phase to a decelerating Sedov-Taylor phase. We predict that this component will peak generally a few tens of years after the explosion and it will outshine the GRB powered afterglow well-before its peak emission. In the case of GRB 030329, where the external density is constrained by the $\sim 10$-year coverage of the radio GRB afterglow, the radio emission is predicted to start rising over the next decade and to continue to increase for the following decades up to a level of $\sim$ mJy. Detection of the SN-powered radio emission will greatly advance our knowledge of particle acceleration in $ \sim 0.1$c shocks.