Effect of turbulence on blazar variability - II: Stochastic variability within leptonic scenario

Abstract

Understanding the origin of the long-term stochastic variability of blazars in different wavebands is a decade-long problem. In this work, we investigate the stochastic variability of blazar emission within the framework of a time-dependent one-zone leptonic model. This model considers the acceleration of the relativistic electrons present in the blazar jet by both the Fermi first order and second order acceleration process, along with radiative energy loss of the same electrons and diffusive escape of those electrons from the acceleration/emission zone. The effect of second order Fermi acceleration is incorporated in the present model through momentum diffusion coefficient considering random scattering of the relativistic electrons by magneto-hydrodynamic (MHD) turbulence. We simulate the variability in the multi-wavelength photon light curves by introducing stochastic variation in the electron injection. Then estimated the power spectral density, probability density function and rms-flux relation to quantify the variability. Here, we show that for different types of stochastic injection process, the nature of the variability changes. The variability properties also depend on the nature of the MHD turbulence present in the system.