A Monte Carlo Radiation Transfer Study of Photospheric Emission in Gamma Ray Bursts

TL;DR

This study uses Monte Carlo radiation transfer simulations to analyze photospheric emission in gamma-ray burst jets, providing insights into spectral evolution and comparison with observed data.

Contribution

It introduces a detailed Monte Carlo radiation transfer approach to model photospheric emission in GRB jets, explicitly tracking photon decoupling and spectral evolution.

Findings

Time-resolved spectra match observed Band parameters.

Results are consistent with the Yonetoku correlation.

Strain observed with the Amati correlation.

Abstract

We present the analysis of photospheric emission for a set of hydrodynamic simulations of long duration gamma-ray burst jets from massive compact stars. The results are obtained by using the Monte Carlo Radiation Transfer code (MCRaT) to simulate thermal photons scattering through the collimated outflows. MCRaT allows us to study explicitly the time evolution of the photosphere within the photospheric region, as well as the gradual decoupling of the photon and matter counterparts of the jet. The results of the radiation transfer simulations are also used to construct light curves and time resolved spectra at various viewing angles, which are then used to make comparisons with observed data, and outline the agreement and strain points between the photospheric model and long duration gamma-ray burst observations. We find that our fitted time resolved spectral Band $\beta$ parameters are in agreement with observations, even though we do not consider the effects of non-thermal particles. Finally, the results are found to be consistent with the Yonetoku correlation, but bear some strain with the Amati correlation.