Constraining the Jet Structure of Gamma-Ray Bursts from Viewing Angle Observations

TL;DR

This paper investigates how viewing angles and reconstructed jet parameters can reveal the structure of gamma-ray burst jets, challenging the uniform jet model and proposing methods to distinguish non-uniform structures.

Contribution

It demonstrates that reconstructed angles are inconsistent with uniform jets and proposes a way to differentiate non-uniform jet structures using GRB observations.

Findings

Reconstructed angles challenge the uniform jet model.

Number of GRBs needed to distinguish jet structures calculated.

Method to infer jet structure from viewing angle data.

Abstract

The angular dependence of emission in gamma-ray bursts (GRB) is of fundamental importance in understanding the underlying physical mechanisms, as well as in multimessenger search efforts. We examine the prospects of using reconstructed GRB jet opening angles and off-axis observer angles in determining the jet structure. We show that the reconstructed angles by Ryan et al. (2015) are inconsistent with uniform jet structure. We further calculate the number of GRBs with accurately reconstructed opening and observer angles necessary to differentiate between some phenomenological non-uniform structures.