The Quintuple Quasar: Radio and Optical Observations

We present results from high-resolution radio and optical observations of PMNJ0134-0931, a gravitational lens with a unique radio morphology and anextremely red optical counterpart. Our data support the theory of Keeton & Winn(2003): five of the six observed radio components are multiple images of asingle quasar, produced by a pair of lens galaxies. Multi-frequency VLBA mapsshow that the sixth and faintest component has a different radio spectrum thanthe others, confirming that it represents a second component of the backgroundsource rather than a sixth image. The lens models predict that there should beadditional faint images of this second source component, and we find evidencefor one of the predicted images. The previously-observed large angular sizes oftwo of the five bright components are not intrinsic (which would have excludedthe possibility that they are lensed images), but are instead due to scatterbroadening. Both the extended radio emission observed at low frequencies, andthe intrinsic image shapes observed at high frequencies, can be explained bythe lens models. The pair of lens galaxies is marginally detected in HSTimages. The differential extinction of the quasar images suggests that theextreme red color of the quasar is at least partly due to dust in the lensgalaxies.Comment: ApJ, in press. 22 pp, 10 fig