Compton dragged supercritical piles: The GRB prompt and afterglow scenario

TL;DR

This paper models GRB prompt and afterglow emissions through a supercritical pile mechanism involving proton-photon interactions, showing how radiation drag influences flow deceleration and observed emission features.

Contribution

It introduces a self-consistent kinetic model for GRBs that incorporates radiation drag and supercritical proton-photon processes, providing new insights into prompt and afterglow emission behaviors.

Findings

Proton accumulation can trigger explosive energy transfer to secondary particles.

Radiation drag can cause rapid deceleration of the GRB outflow.

Model reproduces steep afterglow drops observed by Swift.

Abstract

We examine the prompt and afterglow emission within the context of the Supercritical Pile model for GRBs. For this we have performed self-consistent calculations, by solving three time-dependent kinetic equations for protons, electrons and photons in addition to the usual mass and energy conservation equations. We follow the evolution of the RBW as it sweeps up circumstellar matter and assume that the swept-up electrons and protons have energies equal to the Lorentz factor of the flow. While the electrons radiate their energies through synchrotron and inverse Compton radiation on short timescales, the protons, at least initially, start accumulating without any dissipation. As the accumulated mass of relativistic protons increases, however, they can become supercritical to the `proton-photon pair-production - synchrotron radiation' network, and, as a consequence, they transfer explosively their stored energy to secondary electron-positron pairs and radiation. This results in a burst which has many features similar to the ones observed in GRB prompt emission. We have included in our calculations the radiation drag force exerted on the flow from the scattered radiation of the prompt emission on the circumstellar material. We find that this can decelerate the flow on timescales which are much faster than the ones related to the usual adiabatic/radiative ones. As a result the emission exhibits a steep drop just after the prompt phase, in agreement with the Swift afterglow observations.