2006 Supplement 1: WORKSHOP ON MULTIFREQUENCY BEHAVIOUR OF HIGH ENERGY COSMIC SOURCES: Frascati, 2005 / Jorstad

Multifrequency Polarization Properties of Blazars

S. Jorstad, A. Marscher, J. Stevens, P. Smith, J. Forster, M. Lister, A. Stirling, J. Gómez, T. Cawthorne, W. Gear, I. Robson

Abstract


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 1σ uncertainties. This implies that the high frequency emission is co-spatial with the VLBI core and/or transverse shocks in the jet.


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DOI: https://doi.org/10.1088/1009-9271/6/S1/31

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