1999ApJ...522...74G

We present three-epoch polarimetric images of the quasar 3C 454.3 obtained with the Very Long Baseline Array at 22 and 43 GHz. Polarized intensity images at 22 GHz show a sudden change in the polarization structure of a bright eastern component (which we call the ``core'', although it may be neither at the upstream end of the jet nor completely stationary) over a 41 day interval, coincident with the ejection of a new component from the core, as resolved in the corresponding 43 GHz images. This polarization outburst is also present at 43 GHz in both the core and the new component. This may represent a rapid change in the electric vector position angle of the ejected component from being orthogonal to that of the core to being almost parallel to it. About 7 months later, the new component, moving superluminally at 2.9±0.4 h^–1 c q₀=0.5 relative to the core and 3.9±0.4 h^–1 c relative to a bright stationary component about 0.6 mas west of the core–very low compared with previous measurements–is found at 43 GHz to exhibit a further rotation of 90° in the orientation of its polarization. Opacity effects may account for the first rotation, but changes in the magnetic field of the component and/or that of the underlying jet in the inner milliarcsecond structure of 3C 454.3 are needed to account for the second. Polarized intensity images of the quasar 0420-014, used as a calibrator, are also presented. The polarization position angle of the core rotated between late 1994 and late 1996.