Is the Narrow E-Peak Distribution of Gamma-Ray Bursts Real?

Over the performance period of the research grant, the authors conducted a study of the role that the detector response plays in the detection of gamma-ray bursts. The goal of the study was to determine whether the fact that the gamma-ray bursts observed by the BATSE instrument on the Compton Gamma-ray Observatory are characterized by approximately the same characteristic energy is a consequence of the instrument's characteristics, or whether the distribution is a physical attribute of gamma-ray bursts. The authors succeeded in showing that instrumental effects are mild, and that the observed characteristic energy is a physical attribute of bursts. In the course of this research, the authors ported the computer code for calculating the BATSE detector response matrices to the Sun Solaris platform, and created a version of the code that runs under any platform that supports a Fortran 77 compiler with DEC extensions. This code has already been used by other investigators to analyze BATSE data. The authors constructed a Monte Carlo simulation of the BATSE burst trigger, with which they determined the efficiency of detecting a burst as a function of characteristic burst spectral energy. The results were then applied to BATSE observations to determine the physical model for the distribution of burst characteristic energies.