Multivariate Analysis of BATSE Gamma-Ray Burst Properties Using Skewed Distributions

Abstract

The number of classes of gamma-ray bursts (GRBs), besides the well-established short and long ones, remains a debatable issue. It was already shown, however, that when invoking skewed distributions, the log T 90 and log T 90 −log H 32 spaces are adequately modeled with mixtures of only two such components, implying two GRB types. Herein, a comprehensive multivariate analysis of several multi-dimensional parameter spaces is conducted for the BATSE sample of GRBs, with the usage of skewed distributions. It is found that the number of extracted components varies between the examined parameter sets, and ranges from 2 to 4, with higher-dimensional spaces allowing for more classes. A Monte Carlo testing implies that these additional components are likely to be artifacts owing to the finiteness of the data and be a result of examining a particular realization of the data as a random sample, resulting in spurious identifications.

Graph-based clustering of gamma-ray bursts

“…The reasons are that (i) it has an advantage of being easily displayed graphically, consequently being easy to comprehend at a glance, and (ii) it has been widely explored in the literature allowing for straightforward comparisons. Adding other quantities, for example, fluence (Tarnopolski 2019c, and references therein) to form higher-dimensional spaces is left for a future study.…”

“…Moreover, considering skewed distributions, two-component mixtures have also been indicated (Tarnopolski 2019a,b). In higher-dimensional spaces, things become less unambiguous (Mukherjee et al 1998;Chattopadhyay et al 2007;Chattopadhyay & Maitra 2017Modak et al 2018;Acuner & Ryde 2018;Horváth et al 2019;Tóth et al 2019;Tarnopolski 2019c). For the most recent, detailed overview on the topic of parametric clustering of GRBs, readers can refer to Tarnopolski (2019c).…”

Graph-based clustering of gamma-ray bursts

“…The reasons are that (i) it has an advantage of being easily displayed graphically, consequently being easy to comprehend at a glance, and (ii) it has been widely explored in the literature allowing for straightforward comparisons. Adding other quantities, for example, fluence (Tarnopolski 2019c, and references therein) to form higherdimensional spaces is left for a future study.…”

“…Moreover, considering skewed distributions, two-component mixtures have also been indicated (Tarnopolski 2019b,a). In higher-dimensional spaces, things become less unambiguous (Mukherjee et al 1998;Chattopadhyay et al 2007;Chattopadhyay & Maitra 2017Modak et al 2018;Acuner & Ryde 2018;Horváth et al 2019;Tóth et al 2019;Tarnopolski 2019c). For the most recent, detailed overview on the topic of parametric clustering of GRBs, readers can refer to Tarnopolski (2019c).…”

Search for Cosmological time dilation from Gamma-Ray Bursts -- A 2021 status update

“…GRBs with T 90 > 2 secs are known as long bursts and associated with core-collapse supernovae, whereas those with T 90 < 2 seconds are known as short bursts and usually associated with compact object mergers [4][5][6][7]. There are, however, exceptions to this broad dichotomy, and additional sub-classes of GRBs have also been identified [8][9][10][11]. The smoking gun evidence for the association of short GRBs with compact binary object mergers (involving neutron stars) was, however, provided by the simultaneous detection of gravitational waves and gamma rays from GW170817/GRB170817A [12].…”