Blazar Flares from Compton Dragged Shells

TL;DR

This paper models how shells in blazars experience deceleration due to Compton drag, explaining potential causes of gamma-ray flares and how their light curves relate to shell dynamics and geometry.

Contribution

It introduces a simplified model for the dynamics and emission of shells under strong Compton drag, linking shell deceleration to observed blazar flaring activity.

Findings

Substantial shell deceleration occurs on sub-parsec scales during rapid dissipation.

Flaring activity in gamma-ray blazars can originate from shell deceleration episodes.

Light curve shapes depend on the geometry and dynamics of the emitting shells.

Abstract

We compute the dynamics and emission of dissipative shells that are subject to a strong Compton drag, under simplifying assumptions about the dissipation mechanism. We show that under conditions prevailing in blazars, substantial deceleration is anticipated on sub-parsec and parsec scales in cases of rapid dissipation. Such episodes may be the origin of some of the flaring activity occasionally observed in gamma ray blazars. The shape of the light curves thereby produced reflects the geometry of the emitting surface if the deceleration is very rapid, or the dynamics of the shell if the deceleration is delayed, or initially more gradual, owing, e.g., to continuous injection of energy and momentum.