X-Ray Afterglows

TL;DR

This paper reviews the X-ray variability of GRBs observed by Swift, identifying two main components—prompt and afterglow—and discusses how their spectral and temporal properties differ and relate to theoretical models.

Contribution

It provides a comprehensive summary of the temporal and spectral variability of GRB X-ray afterglows, highlighting the distinct characteristics of prompt and afterglow phases.

Findings

Prompt emission shows strong spectral variability.

Afterglow phase exhibits little spectral variability.

The observed properties challenge existing models to explain temporal and spectral differences.

Abstract

We summarise the X-ray temporal and spectral variability properties of GRBs as observed using the Swift satellite. Despite much individual complexity, the flux and spectral variability can be reasonably well described by a combination of two components - which we denote as the prompt and the afterglow. The first, prompt component consists of the burst and its initial decay while the second, afterglow component fits the X-ray plateau phase and subsequent decline observed in the majority of GRBs. When strong spectral variability occurs it is associated with the prompt component while the X-ray plateau and later emission shows little if any spectral variability. We briefly compare the observations with some of the proposed models. Any model for the early or late emission must explain the differences in both temporal and spectral behaviour.