Marscher, Alan

Multi-waveband Behavior of Blazars.

The author will selectively review the extensive set of comprehensive multi-waveband observations of blazars that has become possible with the availability of the Fermi Gamma Ray Space Telescope. These include light curves from radio to gamma-ray frequencies, linear polarization from radio to optical wavelengths, and spectral energy distributions at different flux states. The combination of cross-frequency correlations, power spectra, timing of the appearance of superluminal knots relative to events in the light curves, and both well-defined and erratic behavior exhibited by blazars is challenging to interpret. Models that incorporate helical magnetic fields in the inner parsec of the jet, and turbulence or shear plus reconnections of magnetic fields on parsec scales, may prove successful, but much work remains to be done.