Parsec‐Scale Jet Polarization Properties of a Complete Sample of Active Galactic Nuclei at 43 GHz

We present results from the highest resolution polarization imaging survey ofa complete sample of extragalactic radio sources carried out to date. Oursample consists of a statistically complete flat-spectrum subset of 32 AGNsfrom the Pearson-Readhead survey, which has been studied at a variety ofwavelengths and resolutions, including space-VLBI. Our observations were madewith the VLBA at 43 GHz, where the relatively higher resolution and weakeropacity effects have allowed us to probe magnetic field structures in the jetsof these AGNs much closer to the central engine than in previous studies. At 43GHz, the bulk of the total intensity and polarized emission in mostflat-spectrum AGNs originates from an unresolved core component located at theextreme end of a faint jet. The luminosity of the core is positively correlatedwith the total source luminosity in soft x-rays, in the optical, and at 5 GHz.The most strongly polarized cores display electric vectors that are roughlyaligned with the jet axis, which is consistent with a strong transverse shockthat enhances the perpendicular component of the jet magnetic field. Sourceswith highly polarized cores also tend to have high optical polarizations andflatter overall radio spectra. Approximately half of the jets in our sampledisplay apparently bent morphologies that are suggestive of streaming motionsalong a helical path. The straightest jets in the sample tend to display slowersuperluminal speeds than those that are significantly bent. We also confirmthat intrinsic differences in the magnetic field properties of BL Lacertaeobjects and quasars previously seen on scales of tens of milliarcseconds arealso present in regions much closer to the base of the jet.Comment: 43 pages, 43 Figures. Accepted for publication in the Astrophysical Journa