Very High Energy Gamma-ray Afterglow Emission of Nearby Gamma-ray Bursts

TL;DR

This paper evaluates the potential for detecting very-high-energy gamma-ray afterglow emission from nearby gamma-ray bursts using ground-based Cherenkov detectors, highlighting detection prospects mainly for exceptionally bright and close bursts like GRB 030329.

Contribution

It provides a detailed analysis of VHE gamma-ray emission from GRB afterglows and assesses the detectability with current Cherenkov detectors, considering cosmic attenuation effects.

Findings

Detection of VHE photons is unlikely for most GRBs with current detectors.

Only very bright and nearby GRBs like GRB 030329 have a feasible detection chance.

Detection is possible under favorable conditions and within 10 hours after the burst.

Abstract

The synchrotron self-Compton (SSC) emission from Gamma-ray Burst (GRB) forward shock can extend to the very-high-energy (VHE; $E_\gamma > $100 GeV) range. Such high energy photons are rare and are attenuated by the cosmic infrared background before reaching us. In this work, we discuss the prospect to detect these VHE photons using the current ground-based Cherenkov detectors. Our calculated results are consistent with the upper limits obtained with several Cherenkov detectors for GRB 030329, GRB 050509B, and GRB 060505 during the afterglow phase. For 5 bursts in our nearby GRB sample (except for GRB 030329), current ground-based Cherenkov detectors would not be expected to detect the modeled VHE signal. Only for those very bright and nearby bursts like GRB 030329, detection of VHE photons is possible under favorable observing conditions and a delayed observation time of $\la$10 hours.