The Radio-Optical Jet in NGC 3862 from Parsec tu Sub-Kiloparsec Scales

We have observed the radio source NGC 3862 (3C264) simultaneously with the EVN and the MERLIN arrays, obtaining detailed images of its radio structure from parsec to sub-kiloparsec scales. 3C264 shows a one-sided jet, with evident variations in its morphological properties with distance. We have analyzed HST optical data of NGC 3862 finding a one-to-one correspondence between radio and optical features in the jet. The radio to optical spectral index is approximately constant along the jet. Synchrotron appears as the most plausible mechanism for the observed jet emission at radio and optical wavelengths. Local particle reacceleration or, alternatively, deviation from the condition of equipartition, are plausible mechanisms to explain the low synchrotron cooling and constant spectral index in the jet of 3C264.