MAPPING COMPOUND COSMIC TELESCOPES CONTAINING MULTIPLE PROJECTED CLUSTER-SCALE HALOS

Lines of sight with multiple projected cluster-scale gravitational lenses have high total masses and complex lens plane interactions that can boost the area of magnification, or etendue, making detection of faint background sources more likely than elsewhere. To identify these new "compound" cosmic telescopes, we have found directions in the sky with the highest integrated mass densities, as traced by the projected concentrations of luminous red galaxies (LRGs). The magnification maps derived from our mass models based on spectroscopy and Sloan Digital Sky Survey photometry alone display substantial etendue: the 68% confidence bands on the lens plane area with magnification exceeding 10 for a source plane of z sub(s) = 10 are [1.2, 3.8] arcmin super(2) for 0850 and [2.3, 6.7] arcmin super(2) for 1306. The significant lensing power of our beams makes them powerful probes of reionization and galaxy formation in the early universe.