Collisional mechanism for GRB emission

TL;DR

This paper proposes that collisional heating in GRB jets creates a hot electron-positron plasma that radiates energy, potentially explaining the observed spectra of gamma-ray bursts.

Contribution

It introduces a detailed simulation of collisional heating in GRB jets, showing it can reproduce observed spectral features and may be the primary emission mechanism.

Findings

Reproduces GRB spectra peaking near 1 MeV

Extends to higher energies with photon index ~ -2.5

Suggests collisional heating as main GRB emission process

Abstract

Nuclear and Coulomb collisions in GRB jets create a hot electron-positron plasma. This collisional heating starts when the jet is still opaque and extends to the transparent region. The e+- plasma radiates its energy. As a result, a large fraction of the jet energy is converted to escaping radiation with a well-defined spectrum. The process is simulated in detail using the known rates of collisions and accurate calculations of radiative transfer in the expanding jet. The result reproduces the spectra of observed GRBs that typically peak near 1 MeV and extend to much higher energies with a photon index \beta ~ -2.5. This suggests that collisional heating may be the main mechanism for GRB emission.