High energy gamma-ray emission from Gamma-Ray Bursts -- before GLAST

TL;DR

This paper reviews observational and theoretical insights into high energy gamma-ray emission from GRBs, emphasizing early afterglow signatures and prospects for detection with upcoming space and ground-based instruments.

Contribution

It provides a comprehensive overview of the expected high energy emission features and discusses detection prospects before the launch of the GLAST satellite.

Findings

High energy gamma-ray emission is linked to early afterglow phases.

Expected signatures could help constrain radiation mechanisms.

Detection prospects with GLAST and ground-based detectors are promising.

Abstract

Gamma-ray bursts (GRBs) are short and intense emission of soft gamma-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high energy gamma-ray emission (>20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high energy emission from GRBs. Special attention is given to the expected high energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.