Prompt GeV-TeV Emission of Gamma-Ray Bursts Due to High-Energy Protons, Muons and Electron-Positron Pairs

TL;DR

This paper models the high-energy gamma-ray emission in GRBs, exploring proton-induced mechanisms and their signatures, which could inform understanding of cosmic rays and neutrinos, using Monte Carlo simulations within the internal shock framework.

Contribution

It introduces detailed Monte Carlo simulations of proton and electron processes in GRBs, highlighting potential spectral signatures of ultra-high-energy protons in the GeV-TeV range.

Findings

Proton-induced mechanisms can produce distinct high-energy spectral features.

Double spectral breaks may serve as signatures of ultra-high-energy protons.

Conditions for proton emission are linked to cosmic ray and neutrino production.

Abstract

In the framework of the internal shock scenario, we model the broadband prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands, utilizing Monte Carlo simulations that include various processes associated with electrons and protons accelerated to high energies. While inverse Compton emission from primary electrons is often dominant, different proton-induced mechanisms can also give rise to distinct high-energy components, such as synchrotron emission from protons, muons or secondary electrons/positrons injected via photomeson interactions. In some cases, they give rise to double spectral breaks that can serve as unique signatures of ultra-high-energy protons. We discuss the conditions favorable for such emission, and how they are related to the production of ultra-high-energy cosmic rays and neutrinos in internal shocks. Ongoing and upcoming observations by {\it GLAST}, atmospheric Cerenkov telescopes and other facilities will test these expectations and provide important information on the physical conditions in GRB outflows.