The Temporal Symmetrical and Translational Structure in Gamma-Ray Burst Light Curves

TL;DR

This study confirms that most gamma-ray burst light curves contain a symmetrical fast-varying component superimposed on a smooth structure, suggesting a common shell collision origin, with potential future radio observations to further explore this.

Contribution

It introduces an alternative model for the smooth component and confirms the presence of symmetrical and translational features in GRB light curves across datasets.

Findings

Most GRBs exhibit symmetrical fast-varying components.

The ratio of symmetrical to translational features is approximately 1:1.

Shell collision structures may explain the observed features.

Abstract

Tremendous information is hidden in the light curve of a gamma-ray burst (GRB). Based on CGRO/BATSE data, Hakkila (2021) found a majority of GRBs can be characterized by a smooth, single-peaked component superposed with a temporally symmetrical residual structure, i.e., a mirror feature for the fast varying component. In this study, we conduct a similar analysis on the same data, as well as on Fermi/GBM data. We got a similar conclusion that most GRBs have this symmetrical fast varying component. Further more, we chose an alternative model to characterize the smooth component and used a three-parameter model to identify the residual, i.e., the fast component. By choosing 226 BATSE GRBs based on a few criteria, we checked the time symmetrical feature and time translational feature for the fast components and found the ratio is roughly 1:1. We propose that both features could come from the structure of the ejected shells. Future SKA might be able to observe the early radio emission from the collision of the shells.