J/ApJ/508/314 Gamma-ray bursts types (Mukherjee+, 1998)
Three types of gamma-ray bursts.
Mukherjee S., Feigelson E.D., Babu J.G., Murtagh F., Fraley C.,
Raftery A.
<Astrophys. J. 508, 314 (1998)>
=1998ApJ...508..314M 1998ApJ...508..314M
ADC_Keywords: Gamma rays
Keywords: gamma rays: bursts - methods: data analysis - methods: statistical
Abstract:
A multivariate analysis of gamma-ray burst (GRB) bulk properties is
presented to discriminate between distinct classes of GRBs. Several
variables representing burst duration, fluence, and spectral hardness
are considered. Two multivariate clustering procedures are used on a
sample of 797 bursts from the Third BATSE Catalog, a nonparametric
average linkage hierarchical agglomerative clustering procedure
validated with Wilks' {LAMBDA}* (1932, Biometrika, 24, 471) and other
multivariate analysis of variance tests and a parametric maximum
likelihood model-based clustering procedure assuming multinormal
populations calculated with the Expectation-Maximization algorithm and
validated with the Bayesian Information Criterion. The two methods
yield very similar results. The BATSE GRB population consists of three
classes with the following duration/fluence/spectrum bulk properties:
class I with long/bright/soft bursts, class II with short/faint/hard
bursts, and class III with intermediate/intermediate/soft bursts. One
outlier due to spurious data is also present. Classes I and II
correspond to those reported by Kouveliotou et al., but class III is
clearly defined here for the first time.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 7 797 Burst classes from average linkage clustering
(3B trigger number)
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See also:
IX/20 : The Fourth BATSE Burst Catalog (Paciesas+ 1998)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1 A1 --- Class [ABCD] (1)
3- 6 I4 ---- Burst Burst number
7 A1 --- Note [*] Note (2)
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Note (1): A: Class I (486 Bursts) long/bright/intermediate bursts
B: Class II (203 Bursts), short/faint/hard,group
C: Class III (107 Bursts) with intermediate/intermediate/soft
properties
D: Class IV (1 Burst)
Note (2): In C class, all bursts are placed into class III by Gaussian
model-based clustering procedure except burst marked * which is
placed into class II
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History: From ApJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 04-Feb-1999