Theories of radiation production in blazar jets have been explored extensively by matching time-averaged or snapshot spectra or global variability properties, such as time-scales or phase and amplitude correlations with predictions of simplified theoretical models. Given the fast variability time-scales and the importance of IC emission/cooling, realistic modeling of outbursts requires time-dependent simulations and it must account for the finite dimension and geometry of the active region. We present results of modeling (SED) multiwavelength variability of one of the brightest and most highly variable Fermi/LAT objects, the powerful FSRQ PKS 1510-089.
We discuss results of scenarios where the flaring is caused by the increase of the number of relativistic electrons ascribed to the effect of the interaction of a portion of the jet (blob) with a shock. We compare different types of inverse Compton emission with respect to the origin of the seed photons (internal, SSC, or external, EC), a question closely related to the more fundamental one concerning the location along the jet of the active region (dissipation distance), in turn giving us clues about the jet structure. Results show clearly the differences produced by a more realistic treatment of the emitting source and demonstrate the crucial importance of time-dependent multi-zone models to advance our understanding of the physics of these sources, by taking full advantage of the wealth of information offered by the high quality data of current multiwavelength campaigns.