On the Connection of Gamma-Ray Bursts and X-Ray Flashes in the BATSE and RHESSI Databases

Abstract

Classification of gamma-ray bursts (GRBs) into groups has been intensively studied by various statistical tests in previous years. It has been suggested that there was a distinct group of GRBs, beyond the long and short ones, with intermediate durations. However, such a group is not securely confirmed yet. Strangely, concerning the spectral hardness, the observations from the Swift and RHESSI satellites give different results. For the Swift/BAT database it is found that the intermediate-duration bursts might well be related to so-called X-ray flashes (XRFs). On the other hand, for the RHESSI dataset the intermediate-duration bursts seem to be spectrally too hard to be given by XRFs. The connection of the intermediate-duration bursts and XRFs for the BATSE database is not clear as well. The purpose of this article is to check the relation between XRFs and GRBs for the BATSE and RHESSI databases, respectively. We use an empirical definition of XRFs introduced by other authors earlier. For the RHESSI database we also use a transformation between the detected counts and the fluences based on the simulated detector response function. The purpose is to compare the hardnesses of GRBs with the definition of XRFs. There is a 1.3-4.2 % fraction of XRFs in the whole BATSE database. The vast majority of the BATSE short bursts are not XRFs because only 0.7-5.7 % of the short bursts can be given by XRFs. However, there is a large uncertainty in the fraction of XRFs among the intermediate-duration bursts. The fraction of 1-85 % of the BATSE intermediate-duration bursts can be related to XRFs. For the long bursts this fraction is between 1.0 % and 3.4 %. The uncertainties in these fractions are large, however it can be claimed that all BATSE intermediate-duration bursts cannot be given by XRFs. At least 79 % of RHESSI short bursts, at least 53 % of RHESSI intermediate-duration bursts, and at least...

29 pages, 14 figures, 10 tables, accepted in Astrophysics and Space Science

References in corpus (15)

• The strongest cosmic magnets: Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars
• Discerning the physical origins of cosmological Gamma-ray bursts based on multiple observational criteria: the cases of z=6.7 GRB 080913, z=8.3 GRB 090423, and some short/hard GRBs
• A new definition of the intermediate group of gamma-ray bursts
• Global Properties of X-Ray Flashes and X-Ray-Rich Gamma-Ray Bursts Observed by Swift
• Further Study of the Gamma-Ray Bursts Duration Distribution
• Classification of Swift's gamma-ray bursts
• The width of gamma-ray burst spectra
• Statistical Study of Observed and Intrinsic Durations among BATSE and Swift/BAT GRBs
• Testing the Randomness in the Sky-Distribution of Gamma-Ray Bursts
• Classification of BeppoSAX's Gamma-Ray Bursts
• Observations of the Prompt Gamma-Ray Emission of GRB 070125
• Redshift distribution of gamma-ray bursts and star formation rate
• Observation of an unexpected hardening in the spectrum of GRB 021206
• Statistical analysis of BATSE gamma-ray bursts: Self-similarity and the Amati-relation
• Factor analysis of the long gamma-ray bursts

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