Page of the paper new definition of the intermediate group of gamma-ray bursts by Istvan Horvath v1.0
authors: I. Horvath, L.G. Balazs, Z. Bagoly, F. Ryde and A. Meszaros
ABSTRACT: It is known that gamma-ray bursts can be divided into three groups ("short", "intermediate", "long") with respect to their durations. This classification is somewhat imprecise, since the subgroup of intermediate durations has an admixture of both short and long bursts. In this paper a physically more reasonable definition of the intermediate group is presented, using also the hardnesses of the bursts. It is shown again that the existence of the three groups is real, and we show that no further groups are needed. We also obtain the result that the intermediate group is the softest one. From this new definition it follows that 11% of all bursts belong to this group. An anticorrelation between the hardness and the duration is found for this subclass in contrast to the short and long groups. Despite this difference it is not clear yet whether this group represents a physically different phenomenon.
Class membership of the bursts: