A sample of 427 gamma-ray bursts (GRBs), measured by the RHESSI satellite, is studied statistically to determine the number of GRB groups. Previous studies based on the BATSE Catalog and recently on the Swift data claim the existence of an intermedia
te GRB group, besides the long and short groups. Using only the GRB durations T90 and chi^2 or F-test, we have not found any statistically significant intermediate group. However, the maximum likelihood ratio test, one-dimensional as well as two-dimensional hardness vs. T90 plane, reveal the reality of an intermediate group. Hence, the existence of this group follows not only from the BATSE and Swift datasets, but also from the RHESSI results.
A sample of 286 gamma-ray bursts (GRBs) detected by the Swift satellite and 358 GRBs detected by the RHESSI satellite are studied statistically. Previously published articles, based on the BATSE GRB Catalog, claimed the existence of an intermediate s
ubgroup of GRBs with respect to duration. We use the statistical chi^2 test and the F-test to compare the number of GRB subgroups in our databases with the earlier BATSE results. Similarly to the BATSE database, the short and long subgroups are well detected in the Swift and RHESSI data. However, contrary to the BATSE data, we have not found a statistically significant intermediate subgroup in either Swift or RHESSI data.
Some articles based on the BATSE gamma-ray burst (GRB) catalog claim the existence of a third population of GRBs, besides long and short. In this contribution we wanted to verify these claims with an independent data source, namely the RHESSI GRB cat
alog. Our verification is based on the statistical analysis of duration and hardness ratio of GRBs. The result is that there is no significant third group of GRBs in our RHESSI GRB data-set.
The Gamma-ray burst (GRB) database based on the data by the RHESSI satellite provides a unique and homogeneous database for future analyses. Here we present preliminary results on the duration and hardness ratio distributions for a sample of 228 GRBs observed with RHESSI.
A sample of almost 400 Gamma-ray bursts (GRBs) detected by the RHESSI satellite is studied statistically. We focus on GRB duration and hardness ratio and use the statistical chi^2 test and the F-test to compare the number of GRB subgroups in the RHES
SI database with that of the BATSE database. Although some previous articles based on the BATSE catalog claim the existence of an intermediate GRB subgroup, besides long and short, we have not found a statistically significant intermediate subgroup in the RHESSI data.
