Campus Units

Statistics

Document Type

Article

Publication Version

Published Version

Publication Date

8-2017

Journal or Book Title

Monthly Notices of the Royal Astronomical Society

Volume

469

Issue

3

First Page

3374

Last Page

3389

DOI

10.1093/mnras/stx1024

Abstract

Clustering methods are an important tool to enumerate and describe the different coherent kind of gamma-ray bursts (GRBs). But their performance can be affected by a number of factors such as the choice of clustering algorithm and inherent associated assumptions, the inclusion of variables in clustering, nature of initialization methods used or the iterative algorithm or the criterion used to judge the optimal number of groups supported by the data. We analysed GRBs from the Burst and Transient Source Experiment (BATSE) 4Br Catalog using k-means and Gaussian-mixture-models-based clustering methods and found that after accounting for all the above factors, all six variables – different subsets of which have been used in the literature – that are, namely, the flux duration variables (T50, T90), the peak flux (P256) measured in 256 ms bins, the total fluence (Ft) and the spectral hardness ratios (H32 and H321) contain information on clustering. Further, our analysis found evidence of five different kinds of GRBs and that these groups have different kinds of dispersions in terms of shape, size and orientation. In terms of duration, fluence and spectrum, the five types of GRBs were characterized as intermediate/faint/intermediate, long/intermediate/soft, intermediate/intermediate/intermediate, short/faint/hard and long/bright/intermediate.

Comments

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Copyright Owner

The Authors

Language

en

File Format

application/pdf

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