Long and short high energy components presented in GRBs

TL;DR

This paper proposes a leptonic external shock model to explain the dual high-energy components in GRBs, attributing short and long GeV emissions to reverse and forward shock SSC processes, respectively.

Contribution

It extends previous models to include both short and long high-energy emissions in GRBs within a magnetized, thick-shell external shock framework.

Findings

Model successfully explains observed fluxes and break energies.

Short high-energy component as SSC from reverse shock.

Longer component as SSC from forward shock.

Abstract

We present a leptonic model on the external shock framework to describe the long- and short- lasting GeV component of some GRBs. This model was already applied successfully to GRB 090926A, and we extend it to describe the high-energy emission of GRB 090902B and GRB 090510. We argue that the high-energy emission consists of two components, one at MeV energies with a duration of a few seconds during the prompt phase, and a second GeV component lasting hundred of seconds after the prompt phase. The short high-energy component can be described as SSC emission from a reverse shock and the longer component arises from SSC emission of the forward shock. The main assumption of our model is that the jet is magnetized and evolves in the thick-shell case. The calculated fluxes and break energies are all consistent with the observed values.