On the Intermediate Subgroup of the Gamma-Ray Bursts in the Swift Database

TL;DR

This study analyzes 286 gamma-ray bursts from the Swift database, confirming the presence of short and long subgroups but not detecting an intermediate subgroup, which may be unified with the short subgroup in other datasets.

Contribution

It provides a statistical analysis of gamma-ray burst subgroups in Swift data, challenging the existence of an intermediate subgroup.

Findings

Short and long subgroups are well detected in Swift data.

No intermediate subgroup is observed in the Swift database.

The non-detection suggests a possible unification of short and intermediate subgroups in other datasets.

Abstract

A sample of 286 gamma-ray bursts, detected by Swift satellite, is studied statistically by the chi^2 test and the Student t-test, respectively. The short and long subgroups are well detected in the Swift data. But no intermediate subgroup is seen. The non-detection of this subgroup in the Swift database can be explained, once it is assumed that in the BATSE database the short and the intermediate subgroups form a common subclass.