Radiative Mechanisms in GRB prompt emission

TL;DR

This paper reviews the challenges and developments in understanding gamma-ray burst prompt emission mechanisms, focusing on optically thick models and hybrid approaches inspired by recent Fermi telescope observations.

Contribution

It synthesizes recent theoretical efforts to explain GRB prompt emission, emphasizing the shift from optically thin models to alternative and hybrid models.

Findings

Optically thin models face difficulties in explaining key observables.

Hybrid models combining optically thick and thin mechanisms are being explored.

Broadening the Planck spectrum remains a key focus in theoretical efforts.

Abstract

Motivated by the Fermi gamma-ray space telescope results, in recent years immense efforts were given to understanding the mechanism that leads to the prompt emission observed. The failure of the optically thin emission models (synchrotron and synchrotron self Compton) increased interest in alternative models. Optically thick models, while having several advantages, also face difficulty in capturing several key observables. Theoretical efforts are focused in two main directions: (1) mechanisms that act to broaden the Planck spectrum; and (2) combining the optically thin and optically thick models to a hybrid model that could explain the key observables.