A Direct Test of the Cosmological Model for Cosmic Gamma-Ray Bursts Based on Peak Alignment Averaging

The cosmological origin of cosmic gamma-ray bursts is tested by using the method of peak alignment for the averaging of time profiles. The test is applied to the basic cosmological model with standard sources, which postulates that the difference between bright and dim bursts results from the different cosmological redshifts of their sources. The average emissivity curve (ACE_bright) of a group of bright BATSE bursts is approximated by a simple analytic function that takes into account the effect of the squeezing of the time pulses with increasing energy of photons. This function is used to build the model light curve for ACE_dim of dim BATSE bursts, which takes into account both the cosmological time-stretching of the light curves of bursts and the redshifting of photon energies. Direct comparison between the model light curve and the ACE_dim of dim bursts is performed, based on the estimated probabilities of differences between ACEs of randomly selected groups of bursts. The comparison shows no evidence for the predicted cosmological effects. The 3 σ upper limit of the average redshift z_dim of emitters of dim bursts is estimated to be as small as ~0.1-0.5, which is not consistent with values of ~1 predicted by current cosmological models of gamma-ray bursts.