Name of the Speaker(s): A. Alberdi¹, L. Lara², J.M. Marcaide³, A. Kemball⁴, K. Leppanen⁵, A. Patnaik⁶, R. Porcas^6
1 IAA, CSIC, Granada, Spain LAEFF, Madrid, Spain
² IRA, Bologna, Italia
³ Univ. Valencia, Valencia, Spain
⁴ NRAO, Socorro, NM, USA
⁵ JIVE, Dwingeloo, Holland
⁶ MPIfR, Bonn, Germany
Title of the communication: DUAL HIGH FREQUENCY POLARIZATION VLBI IMAGES OF 3C395.
Preliminary abstract (12 lines max.):
The radio source 3C395 (1901+319), identified with a 17th magnitude quasar at a redshift z=0.635, presents a core-jet radio structure which consists, on milliarcsecond scales, of two components (A and B) in a position angle of 118 degrees separated 15 milliarcseconds and stationary with respect to each other. 3C395 exhibits strong variability in its total flux density which is the result of the activity in component A, generally identified with the compact core of the radio source. Component B can be explained as the result of a local bend in the jet towards the observer. A third weaker component (C) is located between components A and B. Component C, previously reported as superluminal, appears also stationary since 1990.
We have carried out simultaneous VLBI polarimetric observations of 3C395 at 8.4 and 15 GHz. We find that component A is resolved in a complex core-jet structure with at least two sub-components, with three different orientations of the polarization vectors along the A-region jet, and with curvatures in the inner parts of the jet structure. The rotation of the polarization vectors along the jet could be due to kinks in the jet trajectory itself, to compressive shocks which enhance the component of the magnetic field perpendicular to the jet direction, or to transitions from optically thick to optically thin regimes and viceversa. The relative orientation of the polarization vectors are similar at 8.4 and 15 GHz, except at the westernmost edge coincident with the region identified with the most compact sub-component (probably, the true core). In addition, these observations show that the degree of polarization increases with the frequency, probably due to opacity effects.
In addition, we present VLBI polarization images of the parsec-scale radio-jets of other compact active galactic nuclei, used as calibrators of the 3C395 data.