Gamma-ray burst afterglow blast waves

TL;DR

This review discusses the stages and physics of gamma-ray burst afterglow blast waves, highlighting recent observational and theoretical advances, including the impact of gravitational wave detections on understanding these phenomena.

Contribution

It provides a comprehensive overview of the physical processes and recent progress in modeling gamma-ray burst blast waves, integrating new observational data such as GW 170817.

Findings

Understanding of blast wave dynamics has advanced significantly.

Recent gravitational wave observations offer new insights.

The afterglow emission shifts from X-ray to radio over time.

Abstract

The various stages of baryonic gamma-ray burst afterglow blast waves are reviewed. These are responsible for the afterglow emission from which much of our understanding of gamma-ray bursts derives. Initially, the blast waves are confined to the dense medium surrounding the burster (stellar envelope or dense wind), giving rise to a jet-cocoon structure. A massive ejecta is released and potentially fed by ongoing energy release from the burster and a forward-reverse shock system is set up between ejecta and ambient density. Ultimately the blast wave spreads sideways and slows down, and the dominant afterglow emission shifts from X-rays down to radio. Over the past years significant progress has been made both observationally and theoretically/numerically in our understanding of these blast waves, unique in the universe due to their often incredibly high initial Lorentz factors of 100-1000. The recent discovery of a short gamma-ray burst counterpart to a gravitational wave detection (GW 170817) brings the promise of a completely new avenue to explore and constrain the dynamics of gamma-ray burst blast waves.