The jet of PKS 0521 - 36 - an aging counterpart of M87?

Imaging photometry and VLA mapping at 2 and 6 cm have been used to study the structure and spectral energy distribution of the jet in PKS 0521 - 36. The jet exhibits a strong knot (1.6 kpc from the nucleus) which is resolved at 2 cm and elongated perpendicular to the jet, in a manner suggesting an internal shock. The optical continuum has a spectral index of -2.0 + or - 0.3, with a mean radio-to-optical index of 0.76; this steepens by 0.07 between the inner and outer parts of the jet. A spectral break frequency about 3 times lower than what is seen in M87 is inferred. The radio data suggest that this difference is mostly due to a lower average magnetic field in PKS 0521 - 36 and that the electron energy distributions in both objects extend to gamma about 10 to the 6th. Galactic environments and jet morphologies are compared for the two galaxies.