Simulations of Stochastic Long-term Variability in Leptonic Models for External-Compton and Synchrotron Self-Compton Dominated Blazars

Abstract In this work we investigate the nature of multiwavelength variability of blazars from a purely numerical approach. We use a time-dependent one-zone leptonic blazar emission model to simulate multiwavelength variability by introducing stochastic parameter variations in the emission region. These stochastic parameter variations are generated by Monte Carlo methods and have a characteristic power-law index of α = −2 in their power spectral densities. We include representative blazar test cases for a flat spectrum radio quasar and a high-synchrotron peaked BL Lacertae object for which the high-energy component of the spectral energy distribution is dominated by external-Compton and synchrotron self-Compton emission, respectively. The simulated variability is analyzed in order to characterize the distinctions between the two blazar cases and the physical parameters driving the variability. We show that the variability’s power spectrum is closely related to underlying stochastic parameter variations for both cases. Distinct differences between the different progenitor variations are present in the multiwavelength cross-correlation functions.