The infrared Einstein ring in the gravitational lens MG J1131+0456 and thedeath of the dusty lens hypothesis

We have obtained and modeled NICMOS images of the Einstein ring lens system MG J1131 + 0456, which show that its lens galaxy is an H = 18.6 mag, trans parent, early-type galaxy at a redshift of z(l) similar or equal to 0.84; i t has a major axis effective radius R-e = 0."7 +/- 0."1, projected axis rat io b/a = 0.6 +/- 0.1, and major axis P.A. = 55 degrees +/- 9 degrees. The l ens is the brightest member of a group of at least seven galaxies with simi lar R-I and I-H colors, and the two closest group members produce sufficien t tidal perturbations to explain the shape of the ring. The host galaxy of the MG J1131 + 0456 source is a z(s) greater than or similar to 2 extremely red object (ERO) that is lensed into optical and infrared rings of dramati cally different morphologies. These differences imply a strongly wavelength -dependent source morphology that could be explained by embedding the host in a larger, dusty disk. At 1.6 mu m (H), the ring is spectacularly luminou s, with a total observed flux of H = 17.4 mag and a demagnified flux of 19. 3 mag, corresponding to a 1-2 L-* galaxy at the probable source redshift of z(s) greater than or similar to 2. Thus, it is primarily the stellar emiss ion of the radio source host galaxy that produces the overall colors of two of the reddest radio lenses, MG J1131 + 0456 and JVAS B1938 + 666, aided b y the suppression of optical active galactic nucleus emission by dust in th e source galaxy. The dusty lens hypothesis - that many massive early-type g alaxies with 0 less than or similar to z(l) less than or similar to 1 have large, uniform dust opacities - is ruled out.