Discussion and Conclusions

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Discussion and Conclusions

  1. The counterjet is not a faint replica of the main jet, either in geometry or in brightness. We therefore see little reason to ascribe the primary jet/counterjet intensity asymmetry in 3C353 to relativistic beaming.

  2. The two jets terminate differently. The straighter jet forms a well-defined, oblique, hot spot. The counterjet bends, dims (and perhaps disrupts) entering a ring of emission around the jet axis with no clear hot spot.

  3. There is enhanced emission on the scale of about five jet radii around, and approximately coaxial with, the obvious jet in 3C353. A similar scale of excess emission was seen around the jet in the FR II radio galaxy 3C 219 by Clarke et al. (1992). This scale also resembles that of the ``channel'' around the counterjet in Cygnus A noted by Katz-Stone & Rudnick (1994). The dynamical significance of such emission ``sheaths'' around jets in FR II sources is unclear, but their existence questions whether the brightest jet-like synchrotron emission visualizes all components of the outflows.

  4. There is good evidence for a region of enhanced polarization, with the apparent magnetic field along the jet direction, toward the outer edges of both jets in 3C353. This feature resembles the shear layer needed on the outer boundary of FR I jets in Laing's (1992, and these Proceedings) decelerating-jet model. For a jet near the plane of the sky, this field structure, and some Doppler "hiding" of the emission near the jet axis, can produce flat-topped transverse intensity profiles-as observed. We may therefore have evidence that the internal jet structure postulated by Laing also occurs in this moderately-powered FR II source.