Bagoly, Zs

Balázs, LG

Horváth, I

Szécsi, D

Veres, P

English

ELTE Digital Institutional Repository (EDIT)

arXiv:1508.04946v1  [astro-ph.HE]  20 Aug 2015Gamma-ray burst groups observed byBATSE, Beppo-Sax and SwiftI. Horváth1, L.G. Balázs2, Z. Bagoly3, P. Veres1,3 and D. Szécsi31 Bolyai Military University, Budapest 2Konkoly Observatory, Budapest3Eötvös University, BudapestAbstractShort and long bursts were identified by the BATSE team in theearly 90’s. A decade ago there were some suggestions about the inter-mediate duration type of bursts. We are going to summarize recentanalysises of the duration distributions of the Beppo-Sax and Swiftdata. Our conclusion is all the three satellites (CGRO, Swift, Beppo-Sax) can see the third type of the GRBs. The properties of the groupmembers are very similar in the different data sets.1 IntroductionSeries of papers studied the classification of the Gamma-ray bursts’ (GRBs).They mainly agreed among these misterious phenomena not just short(hard) and long bursts exist but also a third type of GRBs. In this pa-per we are going to summarize these analyses mainly done by the authors.The discovery of the third type of GRBs goes back as early as 1998[1, 2]. After that many research groups studied the BATSE bursts’ sampleand concluded the third group of the GRBs statistically exists [3, 4, 5, 6, 7,8, 9, 10]. Later several studies were published analysing different data sets.We are going to summarize some results according to the CGRO, Swift andBeppo-Sax satellites.1 0 5 10 15 20 25 30 35-1.5 -1 -0.5  0  0.5  1  1.5  2  2.5  3Nlog T90Figure 1: The duration distribution of the Swift bursts and a three Gaussian fit.2 The BATSE sampleThe Compton Gamma-Ray Observatory (CGRO) finished its mission in2000 and the final BATSE catalog was published. The duration distributionof this sample can be well fitted with three Gaussian. The significance thatthe third component is needed is 99.5% [6]. Several papers confirmed similaror even better significance [4, 5, 7, 9, 10].3 The Swift sampleThe First Swift-BAT Catalog [11] was published in 2008. In the catalogthere are 237 GRBs, of which 222 have duration information. The durationdistribution of this sample can be seen in Figure 1. Also a three Gaussianfit is plotted in the figure. The significance of the third component is 99.4% (see [12]). 0 10 20 30 40 50 60 70 80 90-1.5 -1 -0.5  0  0.5  1  1.5  2  2.5  3log T90Figure 2: The duration distribution of the Beppo-Sax GRBs.4 The Beppo-Sax sampleIn the Beppo-Sax catalog [13] there are 1082 GRBs, of which 1003 haveduration information (see Figure 2. for the distribution). For the analysisof this distribution we used the Maximum Likelihood (ML) method. TheML method was not able to identify all the three subgroups in the Beppo-Sax data at a high significance level. However the third group in our analysiswas the shortest in duration. Therefore analyzing the duration distributionobserved by Beppo-Sax GRBM one can find the long and the intermediateduration population [14]. The short population can be seen only with lowsignificance level.5 AcknowledgementsThis research is supported by Hungarian OTKA grant K077795, byOTKA/NKTH A08-77719 and A08-77815 (ZB), and by a Bolyai Scholarship(IH).References[1] MUKHERJEE S. ET AL., ApJ, 508 (1998) 314.[2] HORVÁTH I., ApJ, 508 (1998) 757.[3] HAKKILA J. ET AL., ApJ, 538 (2000) 165.[4] BALASTEGUI A. ET AL., MNRAS, 328 (2001) 283.[5] RAJANIEMI H. J. & MÄHÖNEN P., ApJ, 566 (2002) 202.[6] HORVÁTH I., A&A, 392 (2002) 791.[7] HAKKILA J. ET AL., ApJ, 582 (2003) 320.[8] BORGONOVO L., A&A, 418 (2004) 487.[9] HORVÁTH I. ET AL., A&A, 447 (2006) 23.[10] CHATTOPADHYAY T. ET AL., ApJ, 667 (2007) 1017.[11] SAKAMOTO T. ET AL., ApJS, 175 (2008) 179.[12] HORVÁTH I. ET AL., A&A, 489 (2008) L1.[13] FRONTERA F. ET AL., ApJS, 180 (2009) 192.[14] HORVÁTH I., Ap&SS, 323 (2009) 83.

GRB groups observed by BATSE, BeppoSAX and Swift

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GRB groups observed by BATSE, BeppoSAX and Swift

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