A peculiar multi-wavelength flare in the Blazar 3C 454.3

TL;DR

This paper analyzes a unique multi-wavelength flare in blazar 3C 454.3, revealing complex polarization behavior and modeling the emission with relativistic jet effects, providing insights into jet structure and magnetic fields.

Contribution

It presents a detailed multi-wavelength observational analysis of a peculiar flare in 3C 454.3 and proposes models involving relativistic jet effects and magnetic field configurations.

Findings

Optical polarization increased from ~3% to ~20% during the flare.

Large polarization angle swings of ~170 degrees were observed.

Spectral energy distributions can be modeled with modified one-zone models.

Abstract

The blazar 3C454.3 exhibited a strong flare seen in gamma-rays, X-rays, and optical/NIR bands during 3--12 December 2009. Emission in the V and J bands rose more gradually than did the gamma-rays and soft X-rays, though all peaked at nearly the same time. Optical polarization measurements showed dramatic changes during the flare, with a strong anti-correlation between optical flux and degree of polarization (which rose from ~ 3% to ~ 20%) during the declining phase of the flare. The flare was accompanied by large rapid swings in polarization angle of ~ 170 degree. This combination of behaviors appear to be unique. We have cm-band radio data during the same period but they show no correlation with variations at higher frequencies. Such peculiar behavior may be explained using jet models incorporating fully relativistic effects with a dominant source region moving along a helical path or by a shock-in-jet model incorporating three-dimensional radiation transfer if there is a dominant helical magnetic field. We find that spectral energy distributions at different times during the flare can be fit using modified one-zone models where only the magnetic field strength and particle break frequencies and normalizations need change. An optical spectrum taken at nearly the same time provides an estimate for the central black hole mass of ~ 2.3 * 10^9 M_sun. We also consider two weaker flares seen during the $\sim 200$ d span over which multi-band data are available. In one of them, the V and J bands appear to lead the $\gamma$-ray and X-ray bands by a few days; in the other, all variations are simultaneous.