标题： 红外爱因斯坦环在引力透镜MG1131+0456中的发现及尘埃透镜假说的终结 显示英文标题

标题： The Infrared Einstein Ring in the Gravitational Lens MG1131+0456 and the Death of the Dusty Lens Hypothesis

摘要： 我们获得了并建模了新的NICMOS图像，该透镜系统MG1131+0456显示，其透镜星系是一个红移约为z_l = 0.85的H=18.6星等、透明的早型星系；其主轴有效半径R_e=0.68+/-0.05角秒，投影轴比b/a=0.77+/-0.02，主轴位置角PA=60+/-2度。 该透镜是七个具有相似R-I和I-H颜色的星系群体中最明亮的成员，而两个最近的群体成员产生的潮汐扰动足以解释环状形态。 MG1131+0456源的宿主星系是一个z_s > 2的ERO（“极端红色天体”），它被透镜化为光学和红外环，形态截然不同。 这些差异意味着源形态强烈依赖于波长，这可能由将宿主嵌入一个更大的尘埃盘中来解释。 在1.6微米（H）处，环非常明亮，总观测通量为H=17.4星等，去放大后的通量为19.3星等，对应于在可能的源红移z_s > 2处的1-2L_*星系。 因此，主要是射电源宿主星系的恒星辐射产生了两个最红的射电透镜MG1131+0456和B~1938+666的整体颜色，同时源星系中的尘埃抑制了光学AGN辐射。 尘埃透镜假说——即许多红移0.2 < z_l < 1.0的大量早型星系具有大而均匀的尘埃消光——被排除了。 显示英文摘要

摘要： We have obtained and modeled new NICMOS images of the lens system MG1131+0456, which show that its lens galaxy is an H=18.6 mag, transparent, early-type galaxy at a redshift of about z_l = 0.85; it has a major axis effective radius R_e=0.68+/-0.05 arcsec, projected axis ratio b/a=0.77+/-0.02, and major axis PA=60+/-2 degrees. The lens is the brightest member of a group of seven galaxies with similar R-I and I-H colors, and the two closest group members produce sufficient tidal perturbations to explain the ring morphology. The host galaxy of the MG1131+0456 source is a z_s > 2 ERO (``extremely red object'') which is lensed into optical and infrared rings of dramatically 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 micron (H), the ring is spectacularly luminous, with a total observed flux of H=17.4 mag and a de-magnified flux of 19.3 mag, corresponding to a 1-2L_* galaxy at the probable source redshift of z_s > 2. Thus, it is primarily the stellar emission of the radio source host galaxy that produces the overall colors of two of the reddest radio lenses, MG1131+0456 and B~1938+666, aided by the suppression of optical AGN emission by dust in the source galaxy. The dusty lens hypothesis -- that many massive early-type galaxies with 0.2 < z_l < 1.0 have large, uniform dust opacities -- is ruled out.