Multi-waveband Behavior of Blazars

The author reviews recent progress toward understanding blazars that multi-waveband monitoring observations have advanced. The primary techniques include the compilation of multi-waveband light curves, multi-epoch VLBI images at radio wavelengths, plots of linear polarization vs. time at radio through optical wavelengths, and spectral energy distributions (SEDs). Correlations and the coincidence or lag of events across wavebands and in the images indicate where the events take place relative to the “core” that lies ≳ 0.5 pc from the central engine. Rotations of the polarization electric vector suggest a helical geometry of the magnetic field upstream of the millimeter-wave core, while rapid fluctuations in degree and position angle of polarization imply that the jet plasma is turbulent in and downstream of the core. The author is developing a numerical model that simulates the emission from such turbulence as it interacts with a conical standing shock in the core region