Modeling the radio and optical/NIR afterglows of GRB 980703: a numerical study

TL;DR

This study uses extensive multi-band data of GRB 980703 to test the standard fireball model, successfully explaining its afterglow light curves and deriving key physical parameters of the burst.

Contribution

It provides a detailed numerical analysis of GRB 980703's afterglows, confirming the standard fireball model's applicability and estimating physical parameters.

Findings

Fireball model explains multi-band afterglow data

Beaming angle estimated at ~0.23 radians

Circum-burst medium density ~27 cm^-3

Abstract

Extensive multi-band afterglow data are available for GRB 980703. Especially, its radio afterglow was very bright and was monitored until more than 1000 days after the trigger time. Additionally, there is no obvious special feature, i.e., no rebrightenings, no plateau, and no special steep decay or slow decay in the multi-band afterglow light curves. All these conditions make GRB 980703 a precious sample in gamma-ray burst research. Here we use the observational data of GRB 980703 to test the standard fireball model in depth. It is found that the model can give a satisfactory explanation to the multi-band and overall afterglow light curves. The beaming angle of GRB 980703 is derived as ~0.23 radian, and the circum-burst medium density is ~ 27 cm-3. The total isotropic equivalent kinetic energy of the ejecta is ~ 3.8E52 ergs. A rest-frame extinction of Av ~ 2.5 mag in the host galaxy is also derived.