A new definition of the intermediate group of gamma-ray bursts

Horváth, I.; Balázs, L. G.; Bagoly, Z.; Ryde, F.; Mészáros, A.

doi:10.1051/0004-6361:20041129

Cited by 108 publications

(180 citation statements)

References 30 publications

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“…A solution, proposed to deal with the classification ambiguity problem, was proposed and examined in a number of papers (Hakkila et al 2003;Horváth et al 2004Horváth et al , 2006Horváth et al , 2010Chattopadhyay et al 2007;Veres et al 2010). The idea is to examine a multi-dimensional space of various parameters; particularly, a two-dimensional space of the hardness ratio vs. duration T 90 .…”

Section: Discussionmentioning

confidence: 99%

On the limit between short and long GRBs

Tarnopolski

2015

Astrophys Space Sci

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Two classes of GRBs have been identified thus far without doubt and are prescribed to different physical scenarios-NS-NS or NS-BH mergers, and collapse of massive stars, for short and long GRBs, respectively. The existence of two distinct populations was inferred through a bimodal distribution of the observed durations T 90 , and the commonly applied 2 s limit between short and long GRBs was obtained by fitting a parabola between the two peaks in binned data from BATSE 1B. Herein, by means of a maximum likelihood (ML) method a mixture of two Gaussians is fitted to the datasets from BATSE, Swift, BeppoSAX, and Fermi in search for a local minimum that might serve as a new, more proper, limit for the two GRB classes. It is found that Swift and BeppoSAX distributions are unimodal, hence no local minimum is present, Fermi is consistent with the conventional limit, whereas BATSE gives the limit significantly longer (equal to 3.38 ± 0.27 s) than 2 s. These new values change the fractions of short and long GRBs in the samples examined, and imply that the observed T 90 durations are detector dependent, hence no universal limiting value may be applied to all satellites due to their different instrument specifications. Because of this, and due to the strong overlap of the two-Gaussian components, the straightforward association of short GRBs to mergers and long ones to collapsars is ambiguous.

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Section: Discussionmentioning

confidence: 99%

On the limit between short and long GRBs

Tarnopolski

2015

Astrophys Space Sci

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“…We proceed in an identical way to the successful statistical analysis completed for the BATSE catalog (Horváth 1998) leading to the discovery of the third subgroup (Mukherjee et al 1998;Bagoly et al 1998;Horvath 1999;Hakkila et al 2000;Rajaniemi & Mähönen 2002;Horváth 2002Horváth , 2003Balázs et al 2003;Horváth et al 2006;Chattopadhyay et al 2007). A statistical study of the Swift database -using the maximum likelihood method -has already shown evidence of a third subgroup (Horváth et al 2008).…”

Section: Introductionmentioning

confidence: 97%

“…Any comparison of different databases is highly useful. For example, in the BATSE database, three subgroups (short, intermediate, and long GRBs) have been robustly identified (Horváth et al 2006;Chattopadhyay et al 2007, and references therein). The short and long subgroups are physically different phenomena (Balázs et al 2003).…”

Section: Introductionmentioning

confidence: 99%

“…However, in contrast to this, it remains possible that the intermediate subgroup is not a true physically independent subgroup and it is present in the BATSE database because of e.g. some observational biases caused by the BATSE triggering procedure (Horváth et al 2006). The most reliably way, to resolve the debate concerning whether subgroups or bias are present is to analyze an independent database acquired by another instrument.…”

Section: Introductionmentioning

confidence: 99%

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A comparison of the gamma-ray bursts detected by BATSE and Swift

Huja¹,

Mészáros²,

Řípa³

2009

A&A

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Aims. The durations of 388 gamma-ray bursts detected by the Swift satellite, are analyzed statistically to search for subgroups. The results are then compared with results obtained earlier for data from the BATSE database. Methods. We apply the standard χ 2 test. Results. As for data in the BATSE database, short and long subgroups are also reliably identified in the Swift data. An intermediate subgroup is also seen in the Swift database.Conclusions. The analysis of the entire sample of 388 GRBs provides a support for the existence of three subgroups.

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“…Early hints to the existence of distinct populations of gamma-ray transients (e.g., Mazets et al 1981;Norris et al 1984), and at least two classes of short-hard (Type-I) & long-soft (Type-II) GRBs (Dezalay et al 1992) have now been extensively corroborated and confirmed by the prompt-emission data E-mail: amir@physics.utexas.edu (AS); nemiroff@mtu.edu (RJN) from independent gamma-ray detector missions (e.g., Kouveliotou et al 1993a;Gehrels, Ramirez-Ruiz & Fox 2009; or follow-up observations of the afterglows or host galaxies (e.g., Zhang et al 2009;Berger 2011Berger , 2014. Although the possibility of more than two classes of GRBs with distinct progenitors has been extensively discussed and considered (e.g., Horvath 1998;Mukherjee et al 1998;Hakkila et al 2001;Balastegui, Ruiz-Lapuente & Canal 2001;Hakkila et al 2004b;Horvath et al 2006;Gehrels et al 2006;Chattopadhyay et al 2007;Horvath et al 2008;Virgili, Liang & Zhang 2009;Gao, Lu & Zhang 2010;Horvath et al 2012;Levan et al 2014;Kbori et al 2014), it has remained a matter of debate and speculation to this date (e.g., Hakkila et al 2000cHakkila et al ,a,b, 2003Hakkila et al , 2004aShahmoradi 2013b;Zhang et al 2014;Levan et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Short versus long gamma-ray bursts: a comprehensive study of energetics and prompt gamma-ray correlations

Shahmoradi

Nemiroff

2015

Monthly Notices of the Royal Astronomical Society

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We present the results of a comprehensive study of the luminosity function, energetics, prompt gamma-ray correlations, and classification methodology of short-hard and long-soft GRBs (SGRBs & LGRBs), based on observational data in the largest catalog of GRBs available to this date: BATSE catalog of 2702 GRBs. We find that: 1. The least-biased classification method of GRBs into short and long, solely based on prompt-emission properties, appears to be the ratio of the observed spectral peak energy to the observed duration (R = E p /T 90 ) with the dividing line at R 50[keV s −1 ]. 2. Once data is carefully corrected for the effects of the detection threshold of gammaray instruments, the population distribution of SGRBs and LGRBs can be individually well described as multivariate log-normal distribution in the 4-dimensional space of the isotropic peak gamma-ray luminosity, total isotropic gamma-ray emission, the intrinsic spectral peak energy, and the intrinsic duration. 3. Relatively large fractions of SGRBs and LGRBs with moderate-to-low spectral peak energies have been missed by BATSE detectors. 4. Relatively strong and highly significant intrinsic hardnessbrightness and duration-brightness correlations likely exist in both populations of SGRBs and LGRBs, once data is corrected for selection effects. The strengths of these correlations are very similar in both populations, implying similar mechanisms at work in both GRB classes, leading to the emergence of these prompt gamma-ray correlations.

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A new definition of the intermediate group of gamma-ray bursts

Cited by 108 publications

References 30 publications

On the limit between short and long GRBs

On the limit between short and long GRBs

A comparison of the gamma-ray bursts detected by BATSE and Swift

Short versus long gamma-ray bursts: a comprehensive study of energetics and prompt gamma-ray correlations

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