Time-Dependent, Multi-Wavelength Models for Active Flares of Blazars

Jets in blazars are an excellent forum for studying acceleration atrelativistic shocks using the highly-variable emission seen across theelectromagnetic spectrum. Our recent work on combining multi-wavelengthleptonic emission models with complete simulated distributions fromshock acceleration theory has resulted in new insights into plasmaconditions in blazars. This has demonstrated the ability to infer thecyclotron frequency, the plasma density and thus also the Alfven speed,thereby determining the rapidity of particle energization. An importantinference was that turbulence levels decline with remoteness from jetshocks. In this paper, we deliver new results from our recent extensionof this program to a two-zone, time-evolving construction, modelingtogether both extended, enhanced emission states from larger radiativeregions, and prompt flare events from compact acceleration zones. Theseare applied to the Fermi-LAT and TeV blazars 3C 279 and Mrk 501. Withimpulsive injection episodes from the shock zone, as the accelerationfirst proceeds and then abates, the radiative simulations obtainspectral hysteresis in the hardness-flux diagram in all wavebands. For3C 279, an LBL blazar, while model radio and X-ray synchrotron flares atemporally correlated, there is a lag in both bands relative to GeVgamma-rays and optical emission on timescales of several hours. Thisis governed by the short cooling time associated with the bright externalCompton signal. The results are interpreted in the light of the shockacceleration paradigm, identifying potential observational diagnostics.