VHE Gamma-ray Afterglow Emission from Nearby GRBs

TL;DR

This paper evaluates the potential for current ground-based Cherenkov telescopes to detect very-high-energy gamma-ray afterglow emissions from nearby gamma-ray bursts using the fireball model and SSC emission calculations.

Contribution

It provides the first detailed modeling of VHE afterglow emission from GRBs and assesses detectability with existing Cherenkov telescopes.

Findings

Bright, nearby GRBs like GRB 030329 are detectable in VHE gamma-rays with current instruments.

Detection is feasible even with delayed observations around 10 hours after the burst.

Model predictions align with observational sensitivities of instruments like H.E.S.S. and MAGIC.

Abstract

Gamma-ray Bursts (GRBs) are among the potential extragalactic sources of very-high-energy (VHE) gamma-rays. We discuss the prospects of detecting VHE gamma-rays with current ground-based Cherenkov instruments during the afterglow phase. Using the fireball model, we calculate the synchrotron self-Compton (SSC) emission from forward-shock electrons. The modeled results are compared with the observational afterglow data taken with and/or the sensitivity level of ground-based VHE instruments (e.g. STACEE, H.E.S.S., MAGIC, VERITAS, and Whipple). We find that modeled SSC emission from bright and nearby bursts such as GRB 030329 are detectable by these instruments even with a delayed observation time of ~10 hours.