MULTIFREQUENCY RADIO IMAGES OF THE EINSTEIN RING GRAVITATIONAL LENS MG-1131+0456

We present multifrequency radio images of the Einstein ring gravitatio nal lens system, MG 1131+0456, acquired with the Very Large Array tele scope. Continuum data at 5, 8, 15, and 22 GHz are presented, ranging i n resolution from 0.09'' to 0.39''. Linearly polarized emission, detec ted in the 5 and 8 GHz images, reveals complex structure that will pro vide strong constraints on lens models. We find evidence for flat spec trum components at the positions of the doubly imaged compact componen ts, suggesting that the compact objects are radio cores and that the p ossibility of variability should not be excluded. At 8 GHz, a new unre solved component near the center of the ring is detected; it is likely to be the third and fifth images of parts of the background source. V arying degrees of Faraday rotation, with large rotation measure, are d etected across the source. Variations in depolarization are also seen, and can be reconstructed by a model consisting of a lens with an elli ptical gravitational potential and a radio source with a core, a one-s ided jet, and two extended radio lobes.