Comprehensive multi-wavelength modelling of the afterglow of GRB050525A

TL;DR

This paper presents comprehensive multi-wavelength observations and modeling of GRB 050525A's afterglow, revealing that standard models are insufficient and exploring alternative models to explain complex features.

Contribution

It provides detailed broadband modeling of GRB 050525A's afterglow, testing multiple models and highlighting limitations of the standard blast-wave model.

Findings

Standard blast-wave model cannot explain the afterglow features.

Two-component outflow model fits average behavior but not early fluctuations.

Wind termination shock model fits early light curves but not late-time behavior.

Abstract

The Swift era has posed a challenge to the standard blast-wave model of Gamma Ray Burst (GRB) afterglows. The key observational features expected within the model are rarely observed, such as the achromatic steepening (`jet-break') of the light curves. The observed afterglow light curves showcase additional complex features requiring modifications within the standard model. Here we present optical/NIR observations, millimeter upper limits and comprehensive broadband modelling of the afterglow of the bright GRB 0505025A, detected by Swift. This afterglow cannot be explained by the simplistic form of the standard blast-wave model. We attempt modelling the multi-wavelength light curves using (i) a forward-reverse shock model, (ii) a two-component outflow model and (iii) blast-wave model with a wind termination shock. The forward-reverse shock model cannot explain the evolution of the afterglow. The two component model is able to explain the average behaviour of the afterglow very well but cannot reproduce the fluctuations in the early X-ray light curve. The wind termination shock model reproduces the early light curves well but deviates from the global behaviour of the late-time afterglow.