On The Origin Of High Energy Correlations in Gamma-ray Bursts

I investigate the origin of the observed correlation between a gamma-ray burst’s νFν spectral peak Epk and its isotropic equivalent energy Eiso through the use of a population synthesis code to model the prompt gamma-ray emis-sion from GRBs. By using prescriptions for the distribution of prompt spectral parameters as well as the population’s luminosity function and co-moving rate density, I generate a simulated population of GRBs and examine how bursts of varying spectral properties and redshift would appear to a gamma-ray detec-tor here on Earth. I find that a strong observed correlation can be produced between the source frame Epk and Eiso for the detected population despite the existence of only a weak and broad correlation in the original simulated popu-lation. The energy dependance of a gamma-ray detector’s flux-limited detection threshold acts to produce a correlation between the source frame Epk and Eiso for low luminosity GRBs, producing the left boundary of the observed correla-tion. Conversely, very luminous GRBs are found at higher redshifts than thei