A multizone view on the multiwavelength emission of blazars

ABSTRACT In this work, a time-dependent modelling 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 broad-band 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 multiwavelength 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 multiwavelength spectral energy distributions, light curves, and polarization 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 polarization-angle swings, which are difficult to explain under the conventional one-zone models simultaneously.