Analysis of the Swift Gamma-Ray Bursts duration

TL;DR

This paper reanalyzes gamma-ray burst durations from the Swift BAT catalog, finding evidence for three distinct classes of bursts using statistical modeling, which refines previous two-class classifications.

Contribution

It introduces a three-component log-normal model for GRB durations in the Swift data, providing stronger statistical evidence for a third class of gamma-ray bursts.

Findings

Three log-normal components fit the duration distribution better than two.

Statistical significance exceeds 99%, confirming three classes.

Supports existence of a potential third GRB class.

Abstract

Two classes of gamma-ray bursts have been identified in the BATSE catalogs characterized by durations shorter and longer than about 2 seconds. There are, however, some indications for the existence of a third type of burst. Swift satellite detectors have different spectral sensitivity than pre-Swift ones for gamma-ray bursts. Therefore it is worth to reanalyze the durations and their distribution and also the classification of GRBs. Using The First BAT Catalog the maximum likelihood estimation was used to analyzed the duration distribution of GRBs. The three log-normal fit is significantly (99.54 % probability) better than the two for the duration distribution. Monte-Carlo simulations also confirm this probability (99.2 %).