Spatially Resolved Millimeter Spectroscopy of the Gravitational Lens PKS 1830−211

This paper presents data from the BIMA interferometer showing spatiallyresolved absorption spectra of the gravitationally lensed quasar PKS 1830-211.High-resolution (1.2 km/s) spectra were taken in two spectral windows centeredon the redshifted frequencies of the HCO+(2-1) and HCN(2-1) moleculartransitions. There is no molecular absorption in the northeast image but thesouthwest image reveals optically thick absorbing gas at these transitionfrequencies. Further analyses conclude that the spectra are consistent withcompletely saturated absorption in the southwest image and the line profilessuggest that the absorbing medium is complex, perhaps containing multiplecomponents and small scale structure. The absorption occurs along a pencil beamthrough the lensing galaxy which is thought to be a late type spiral orientedalmost face on. However, the spectra show absorption spanning more than 60 km/swhich is difficult to explain for this scenario.Comment: 9 pages, 1 figure. accepted ApJ.Le