Consistency of GRB durations and spectra with standard cosmology

Abstract

We present an analysis of the consistency of burst durations and spectra with a population of nonevolving sources at Gpc distances. The parameters T90 (T50) and Ep are calculated using data obtained with BATSE, and are used to characterize burst durations and spectra, respectively. Effects consistent with cosmological redshift and time dilation have been reported in the Ep and T90 data, respectively. We simultaneously examine the distributions of these parameters for cosmological time dilation and redshift effects, being careful to avoid the introduction of selection effects. We show that the T90 (T50) data are currently less constraining than Ep; the data do not require time dilation, but are consistent with the effect observed in the Ep data.