DEEP RADIO OBSERVATIONS OF 3C-324 AND 3C-368 - EVIDENCE FOR JET-CLOUDINTERACTIONS

High-resolution, deep radio images are presented for two distant radio galaxies, 3C 324 (z = 1.206) and 3C 368 (z = 1.132), which are both p rime examples of the radio-optical alignment effect seen in powerful r adio galaxies with redshifts z greater than or similar to 0.6. Radio o bservations were made using the Very Large Array in A-array configurat ion at 5 and 8 GHz, and using the MERLIN array at 1.4 and 1.65 GHz, Ra dio spectral index, radio polarization, and rotation measure maps are presented for both sources. Radio core candidates are detected in each source, and by aligning these with the centroid of the infrared emiss ion the radio and the optical/infrared images can be related astrometr ically with 0.1 arcsec accuracy. In each source the radio core is loca ted at a minimum of the optical emission, probably associated with a c entral dust lane. Both sources also exhibit radio jets which lie along the directions of the bright strings of optical knots seen in high-re solution Hubble Space Telescope images. The northern arm of 3C 368 sho ws a close correlation between the radio and optical emission, whilst along the jet direction of 3C 324 the bright radio and optical knots a re co-linear but not co-spatial. These indicate that interactions betw een the radio jet and its environment play a key role in producing the excess ultraviolet emission of these sources, but that the detailed m echanisms vary from source to source. 3C 368 is strongly depolarized a nd has an average rest-frame rotation measure of a few hundred rad m(- 2), reaching about 1000 rad m(-2) close to the most depolarized region s. 3C 324 has weaker depolarization, and an average rest-frame rotatio n measure of between 100 and 200 rad m(-2), Both sources show large gr adients in their rotation measure structures, with variations of up to 1000 rad m(-2) over distances of about 10 kpc.