A multi-zone view on the multi-wavelength emission of blazars

TL;DR

This paper develops a time-dependent, multi-zone model for blazar emission, explaining complex observational phenomena like variability and polarization that single-zone models struggle with.

Contribution

It introduces a multi-zone, time-dependent framework for modeling blazar emission, capturing diverse observational features simultaneously.

Findings

Reproduces flat radio spectra and core-shift phenomena.

Explains minute-scale gamma-ray variability.

Accounts for large polarization-angle swings.

Abstract

In this work, a time-dependent modeling is developed to study the emission properties of blazars in the low state. Motivated by various observations, we speculate and assume that numerous discrete radiation zones throughout the jet of a blazar contribute to the broadband emission. We model the temporal evolution of the electron spectrum in each emission zone taking into account the injection, cooling and escape of relativistic electrons. By doing so, we are able to calculate the multi-wavelength emission of each radiation zone. The observed emission of a blazar is then the superposition of the emission from all discrete radiation zones. We revisit the multi-wavelength spectral energy distributions, light curves and polarisation under the model, and discuss its potential to reproduce the flat radio spectra, the core-shift phenomena, the minute-scale gamma-ray variability, and the large polarisation-angle swings, which are difficult to explain under the conventional one-zone models simultaneously.