Detailed Classification of Swift's Gamma-Ray Bursts

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 Beppo-SAX 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, the maximum likelihood method favors the three component against the two component model. The likelihood also shows that a fourth component is not needed.