COSMOLOGICAL TIME DILATION IN SHORT GAMMA-RAY BURSTS

Using the parameter V[=((C) over bar(64))(max)/((C) over bar(1024))(ma x)], the ratio of expected peak counts in 64 ms and 1024 ms, proposed by Che et al. recently, we find the cosmological time dilation in shor t gamma-ray bursts (t(90) < 1.5 s) directly from the Burst and Transie nt Source Experiment catalog. The parameter V of short bursts shows a good correlation with the brightness B when we use ((C) over bar(64))( max) as a measure of brightness B rather than ((C) over bar(1024))(max ), introduced by Lamb et al. in 1993. In a Friedmann universe with Ome ga = 1 and Lambda = 0, the estimated redshift is about 2 and the time dilation factor (TDF) with the energy correction is about 1.8. The fac t that these results generally agree with those found in long bursts s upports the same origin of long and short gamma-ray bursts.