Multifrequency polarization properties of blazars
Chinese Journal of Astronomy and Astrophysics 6,(2006) 247-252;
We report preliminary results of a 3-year multifrequency polarization campaign of 15 AGNs of blazar type, including bimonthly total and polarized intensity imaging at 7 mm with the VLBA. We find that the sources have two different dependences of degree of polarization on wavelength: sub-mm peaked or straight "polarization spectra". The fractional polarization of the latter group increases with frequency. All sources with sub-mm peak polarization (6 objects) have similar degree of polarization in the optical region and in the VLBA core. In high-optically polarized sources (5 objects) the EVPAs at all frequencies align with the pc-scale jet direction within the 1 sigma uncertainties. This implies that the high frequency emission is co-spatial with the VLBI core and/or transverse shocks in the jet.
active;; galaxies : quasars : individual (0420-014, 0528+134, 3C 273, 3C;; 279, PKS 1510-089, 3C 345, CTA 102, 3C 454.3);; galaxies : BL Lacertae;; objects : individual (3C 66A, OJ 287, 1803+784, 1823+568, BL Lac);; galaxies : individual (3C 111, 3C 120);; galaxies : jet;; Astronomy & Astrophysics
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