High resolution observation of 3C 66B

The Faint Object Camera on the HST has imaged the central region of the synchrotron jet in 3C 66B with very high spatial resolutions−0.1 arcsec, corresponding to 40 pc. We have also obtained high resolution 15 GHz VLA observations that show general agreement with the FOC images. The correspondence between the characteristics of the optical image and the radio map implies that the young (<1000 yr) and old (≳107 yr) relativistic particles occupy similar regions. The very fine double‐stranded filamentary features present on the full‐resolution images are particularly intriguing. This could reflect edge‐brightening effects due to enhanced radiation from a skin‐like structure surrounding the jet, or intrinsically filamentary emission. The similarity of optical and radio morphologies suggests that localized particle acceleration occurs along the jet. However, filamentary structure and low filling factor may also be consistent with a model in which the electrons are accelerated at the nucleus and transported alo...