The Role of T_(50) in the Classification of Gamma-ray Bursts

摘要

The role of T50 in classifying gamma-ray bursts(GRBs)is investigated.We take T50 = 0.Ts as the line of division and find that some bursts belonging to the class of long bursts defined by T90 ≥ 2s now become short bursts(sample 1),while some belonging to the class of short bursts defined by T90 ＜ 2 s now become long bursts(sample 2).We study how these sources are affected by the two methods of classification and find the change of classes of sample 1 is due to some peculiar properties of the light curves.Based on their characters,most of the bursts of sample 1 should be taken as short bursts.