Hints of the jet composition in gamma-ray bursts from dissipative photosphere models

TL;DR

This paper proposes a dissipative photosphere model for gamma-ray bursts that explains spectral features and jet composition by analyzing thermal and non-thermal emission correlations, providing insights into whether jets are Poynting flux or baryon dominated.

Contribution

It introduces a unified model for GRB spectra that links thermal and non-thermal components to jet composition, using observational correlations.

Findings

Thermal and non-thermal peak correlations reveal jet composition.

GeV emission results from photospheric radiation interacting with shocked electrons.

The model distinguishes Poynting flux from baryon-dominated jets.

Abstract

We present a model for gamma-ray bursts where a dissipative photosphere provides the usual spectral peak around MeV energies accompanied by a subdominant thermal component. We treat the initial acceleration of the jet in a general way, allowing for magnetic field- and baryon dominated outflows. In this model, the GeV emission associated with GRBs observed by Fermi LAT, arises as the interaction of photospheric radiation and the shocked electrons at the deceleration radius. Through recently discovered correlations between the thermal and non-thermal peaks within individual bursts, we are able to infer whether the jet was Poynting flux or baryon dominated.