The late-time radio behavior of GRB afterglows: testing the standard model

Understand

We examine a sample of 21 gamma-ray burst (GRB) afterglow light curves at radio frequencies, and compare them to the X-ray and/or optical properties of the afterglows and to the predictions of the standard jet/fireball model.

• Our sample includes every \textit{Swift} GRB with an X-ray light curve indicating a jet break and with a published radio light curve, as well as several other targets with observed X-ray or and/optical jet breaks.
• We examine the late-time decline of each burst, and attempt to fit an analytical model based on the standard GRB afterglow equations to each data set.
• We show that most of the events in our \textit{Swift} GRB sample are incompatible with the radio light curve behavior predicted by conventional afterglow theory.