THE LENSING CLUSTER IN THE WIDEST SEPARATION GRAVITIONAL LENS

We propose deep XMM imaging of a system of two QSOs separated by 33 arcsecondsat z2.4, that is likely the most widely separated gravitational lens known. Theevidence of lensing is (1) the overall similarity of the optical spectra, (2)the almost identical Lymanalpha forest near the emission redshift, and (3) thepresence of a bright galaxy near the implied lensing mass center. The 15 ksintegration time is designed to easily detect a cluster of the mass implied by alens model at the most probable redshift (z0.44) and marginally detect acluster at the highest plausible redshift (z1). The Xray properties of thisfirst ever massselected cluster are of interest, and the confirmation of even asingle lens of this separation leads to significant cosmological constraints. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]