First-Principle-Integrated Study of Blazar Synchrotron Radiation and Polarization Signatures from Magnetic Turbulence

TL;DR

This study combines first-principle PIC and radiative transfer simulations to analyze how magnetic turbulence influences blazar synchrotron radiation and polarization, revealing stochastic variability patterns and polarization swings.

Contribution

It provides the first systematic study of blazar emission signatures using integrated PIC and polarized radiative transfer simulations, linking turbulence properties to observable polarization features.

Findings

Polarization angle swings can occur with arbitrary amplitudes and durations.

Flux and polarization variability are governed by turbulence correlation length.

Simulated signatures are consistent with the TEMZ model.

Abstract

Blazar emission is dominated by nonthermal radiation processes that are highly variable across the entire electromagnetic spectrum. Turbulence, which can be a major source of nonthermal particle acceleration, can widely exist in the blazar emission region. The Turbulent Extreme Multi-Zone (TEMZ) model has been widely used to describe turbulent radiation signatures. Recent particle-in-cell (PIC) simulations have also revealed the stochastic nature of the turbulent emission region and particle acceleration therein. However, radiation signatures have not been systematically studied via first-principle-integrated simulations. In this paper, we perform combined PIC and polarized radiative transfer simulations to study synchrotron emission from magnetic turbulence in the blazar emission region. We find that the multi-wavelength flux and polarization are generally characterized by stochastic patterns. Specifically, the variability time scale and average polarization degree (PD) are governed by the correlation length of the turbulence. Interestingly, magnetic turbulence can result in polarization angle (PA) swings with arbitrary amplitudes and duration, in either directions, that are not associated to changes in flux or PD. Surprisingly, these swings, which are of stochastic nature, can appear either bumpy or smooth, although large amplitude swings ($>180^{\circ}$) are very rare as expected. Our radiation and polarization signatures from first-principle-integrated simulations are consistent with the TEMZ model.