Detailed Classification of Swift's Gamma-Ray Bursts

TL;DR

This paper extends gamma-ray burst classification by analyzing Swift data with spectral and duration information, confirming three main groups without requiring a fourth component, using maximum likelihood methods.

Contribution

It introduces a spectral analysis to the classification of Swift gamma-ray bursts, reinforcing the three-group model with statistical evidence.

Findings

Three gamma-ray burst groups confirmed in Swift data.

Spectral hardness combined with duration supports three-component model.

No evidence for a fourth gamma-ray burst class.

Abstract

Earlier classification analyses found three types of gamma-ray bursts (short, long and intermediate in duration) in the BATSE sample. Recent works have shown that these three groups are also present in the RHESSI and the BeppoSAX databases. The duration distribution analysis of the bursts observed by the Swift satellite also favors the three-component model. In this paper, we extend the analysis of the Swift data with spectral information. We show, using the spectral hardness and the duration simultaneously, that the maximum likelihood method favors the three-component against the two-component model. The likelihood also shows that a fourth component is not needed.