Hyperluminal Signatures in the Afterglows of Gamma-Ray Bursts 980425 and 030329

TL;DR

This paper presents evidence of hyperluminal expansion in the afterglows of two gamma-ray bursts, supporting the cannonball model and suggesting superluminal motion in GRB sources.

Contribution

It provides observational evidence of superluminal expansion in GRB afterglows consistent with the cannonball model, a novel interpretation for these phenomena.

Findings

Hyperluminal speed ~350c in GRB980425/SN1998bw.

Superluminal expansion observed in GRB030329/SN2003dh.

Results support the cannonball model of GRBs.

Abstract

The late-time high-resolution X-ray and radio observations of GRB980425/SN1998bw, the closest known gamma ray burst (GRB) associated with a supernova (SN) explosion, may have actually resolved the hyperluminal source that produced the GRB and its afterglow. Its hyperluminal speed ~350c is consistent with that expected in the cannonball (CB) model of GRBs. The observed superluminal expansion of the late-time radio image of GRB030329/SN2003dh, the GRB with the brightest and longest followed up radio afterglow to date, is also consistent with that expected in the CB model of GRBs and extrapolates to an apparent early-time hyperluminal expansion.