Photospheric Emission From Variable Engine Gamma Ray Burst Simulations

Abstract

By coupling radiation transfer calculations to hydrodynamic simulations, there have been major advancements in understanding the long Gamma Ray Burst (LGRB) prompt emission. Building upon these achievements, we present an analysis of photospheric emission acquired by using the Monte Carlo Radiation Transfer (MCRaT) code on hydrodynamic simulations with variable jet profiles. MCRaT propagates and Compton scatters individual photons that have been injected into the collimated outflow in order to produce synthetic light curves and spectra. These light curves and spectra allow us to compare our results to LGRB observational data. We find excellent agreement between our fitted time resolved $\beta$ parameters and those that are observed. Additionally, our simulations show that photospheric emission, under certain conditions, is able to create the observationally expected Band $\alpha$ parameter. Finally, we show that the simulations are consistent with the Golenetskii correlation but exhibit some strain with the Amati and Yonetoku correlations.