The radio-optical jet in NGC 3862 from parsec to subkiloparsec scales

We have observed the radio source in NGC 3862 (3C 264) simultaneously with the European VLBI network and the MERLIN arrays, obtaining detailed images of its radio structure from parsec to sub-kiloparsec scales. 3C 264 shows a one-sided jet with evident variations in its morphological properties with distance. We have analyzed Hubble Space Telescope 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 3C 264.