Wardle, John

Magnetic fields and polarization in AGN jets.

In the literature there are now a wealth of images of AGN in both linear and circular polarization at milliarcsecond resolution of many sources at multiple epochs and wavelengths. This review will be a broad overview of our current state of knowledge of the polarization properties of AGN jets, and of what we can infer about the structure of their magnetic fields and the distribution of Faraday rotating material (and also what is premature to infer). I will discuss the “value added” by observing in all 4 Stokes parameters coupled with detailed modeling using the full equations of transfer for polarized radiation. This permits the determination of important physical parameters of the jet that are otherwise poorly constrained or unknown. I will mention briefly what might be learned using the new technique of Faraday synthesis, and also the prospects for imaging polarized radiation near supermassive black holes using the Event Horizon Telescope.