Polarization Swings Reveal Magnetic Energy Dissipation in Blazars

TL;DR

This paper models polarization swings in blazars as light-travel-time effects, linking spectral, variability, and polarization data to magnetic energy dissipation in jets, with application to 3C279.

Contribution

It presents the first simultaneous fit of multi-wavelength spectrum, variability, and polarization for a blazar flare, constraining jet magnetic topology and energy dissipation mechanisms.

Findings

Polarization swings can be explained by light-travel-time effects.

Magnetic energy dissipation drives the flare event.

Constraints on particle acceleration and magnetic field structure in jets.

Abstract

The polarization signatures of the blazar emissions are known to be highly variable. In addition to small fluctuations of the polarization angle around a mean value, sometimes large (> 180^o) polarization angle swings are observed. We suggest that such p henomena can be interpreted as arising from light-travel-time effects within an underlying axisymmetric emission region. We present the first simultaneous fitting of the multi-wavelength spectrum, variability and time-dependent polarization features of a correlated optical and gamma-ray flaring event of the prominent blazar 3C279, which was accompanied by a drastic change of its polarization signatures. This unprecedented combination of spectral, variability, and polarization information in a coherent physical model allows us to place stringent constraints on the particle acceleration and magnetic-field topology in the relativistic jet of a blazar, strongly favoring a scenario in which magnetic energy dissipation is the primary driver of the flare event.