Direct and bulk-scattered forward-shock emissions: sources of X-ray afterglow diversity

TL;DR

This paper proposes a modified forward-shock model involving a delayed, pair-enriched outflow that bulk-scatters synchrotron emission, explaining diverse early X-ray afterglow features observed by Swift.

Contribution

It introduces a new mechanism involving bulk scattering by a delayed outflow to account for complex X-ray afterglow behaviors.

Findings

Explains X-ray flares and plateaus with the scattering model.

Accounts for chromatic breaks in X-ray light curves.

Describes fast post-plateau X-ray decays.

Abstract

I describe the modifications to the standard forward-shock model required to account for the X-ray light-curve features discovered by Swift in the early afterglow emission and propose that a delayed, pair-enriched, and highly relativistic outflow, which bulk-scatters the forward-shock synchrotron emission, yields sometimes a brighter X-ray emission, producing short-lived X-ray flares, X-ray light-curve plateaus ending with chromatic breaks, and fast post-plateau X-ray decays.