Catching GRBs with atmospheric Cherenkov telescopes

TL;DR

This paper estimates the potential detection rate of high-energy gamma-ray bursts (GRBs) by the upcoming Cherenkov Telescope Array, suggesting that ground-based detection is challenging but feasible and could provide insights into GRB emission mechanisms and the Extragalactic Background Light.

Contribution

The study combines Fermi observations with lower-energy burst data to predict GRB detection rates for the CTA, highlighting the potential for ground-based observations of VHE GRBs.

Findings

Estimated detection rate of 0.25-0.5 GRBs per year with CTA.

Detection could constrain GRB emission mechanisms.

Ground-based detection can probe the Extragalactic Background Light.

Abstract

Fermi has shown GRBs to be a source of >10 GeV photons. We present an estimate of the detection rate of GRBs with a next generation Cherenkov telescope. Our predictions are based on the observed properties of GRBs detected by Fermi, combined with the spectral properties and redshift determinations for the bursts population by instruments operating at lower energies. While detection of VHE emission from GRBs has eluded ground-based instruments thus far, our results suggest that ground-based detection may be within reach of the proposed Cherenkov Telescope Array (CTA), albeit with a low rate, 0.25 - 0.5/yr. Such a detection would help constrain the emission mechanism of gamma-ray emission from GRBs. Photons at these energies from distant GRBs are affected by the UV-optical background light, and a ground-based detection could also provide a valuable probe of the Extragalactic Background Light (EBL) in place at high redshift.