High-Resolution, High Dynamic Range VLA Images of the M87 Jet at 2 Centimeters

New radio observations of the M87 jet are reported. The observations were made with the VLA in the A array at 2 cm which yields a resolution of 0.1". Using new observing and reduction techniques, a dynamic range of about 50,000 to 1 has been achieved. The new maps show a complex pattern of filamentary and other fine scale structure in the jet. The new details seen in the jet point to new interpretations of the emission. The jet is clearly limb-brightened at points. Patterns of "filaments" appear to wrap around the jet and suggest that the jet is not too far out of the plane of the sky. Several features seem to have very sharp edges. Finally, most of the emission profiles across the jet are flat-topped or edge-brightened. These results are consistent with an emissivity which is much higher in a thin boundary layer than elsewhere in the jet. In general, minimum pressures are 3-50 times higher than the pressures in the external medium estimated from the X-ray images. The projected magnetic field vectors typically lie along the jet. However, vectors with significant transverse components are found all along the jet, especially at the bright features A and C. These vectors suggest a significant azimuthal component of the magnetic field which can assist in confining the jet. The overall morphology is more consistent with a boundary layer phenomena rather than a structure dominated by shocks or other centrally driven flow phenomena and suggest a picture in which electrodynamic phenomena play an important role in the physics.