Evolution of jets driven by relativistic radiation hydrodynamics as long and low-luminosity GRBs

Abstract

We present numerical simulations of jets modelled with relativistic radiation hydrodynamics (RRH), which evolve across two environments: (i) a stratified surrounding medium and (ii) a 16TI progenitor model. We consider opacities consistent with various processes of interaction between the fluid and radiation, specifically free–free, bound–free, bound–bound, and electron scattering. We explore various initial conditions, with different radiation energy densities of the beam in hydrodynamical and radiation-pressure-dominated scenarios, considering only highly relativistic jets. In order to investigate the impact of the radiation field on the evolution of the jets, we compare our results with purely hydrodynamical jets. Comparing among jets driven by an RRH, we find that radiation-pressure-dominated jets propagate slightly faster than gas pressure dominated ones. Finally, we construct the luminosity light curves (LCs) associated with the two cases. The construction of LCs uses the fluxes of the radiation field that is fully coupled to the hydrodynamics equations during the evolution. The main properties of the jets propagating on the stratified surrounding medium are that the LCs show the same order of magnitude as the gamma-ray luminosity of typical Long gamma-ray bursts 1050–1054 erg s−1, and the difference between the radiation and gas temperatures is of nearly one order of magnitude. The properties of jets breaking out from the progenitor star model are that the LCs are of the order of magnitude of low-luminosity GRBs 1046−1049 erg s−1, and in this scenario, the difference between the gas and radiation temperature is of four orders of magnitude, which is a case far from thermal equilibrium.