The early high-energy afterglow emission from Short GRBs

TL;DR

This paper models the early high-energy afterglow emission from short Gamma-Ray Bursts, showing synchrotron emission dominates and can be detectable by Fermi LAT under certain conditions.

Contribution

It provides the first detailed calculation of high-energy afterglow components in short GRBs, highlighting the dominance of synchrotron emission and its detectability.

Findings

Synchrotron emission dominates the early high-energy afterglow.

Detection is possible by Fermi LAT for nearby bursts with sufficient energy.

Explains the high-energy tail observed in GRB 081024B.

Abstract

We calculate the high energy afterglow emission from short Gamma-Ray Bursts (SGRBs) in the external shock model. There are two possible components contributing to the high energy afterglow: the electron synchrotron emission and the synchrotron self-Compton (SSC) emission. We find that for typical parameter values of SGRBs, the early high-energy afterglow emission in 10 MeV-10 GeV is dominated by the synchrotron emission. For a burst occurring at redshift z =0.1, the high-energy emission can be detectable by Fermi LAT if the blast wave has an energy E>=10^51 ergs and the fraction of energy in electrons is \epsilon_e>=0.1 . This provides a possible explanation for the high energy tail of SGRB 081024B.