(Proposal ID) S14A-158

(PI) Wong, Kenneth

(Proposal Title)
 Studying the Most Powerful Gravitational Lens Telescopes with Suprime-Cam

(Abstract)
Detecting the earliest galaxies at z > 7 is a major challenge in observational 
cosmology. Past studies have required a large investment of HST time and have 
only found a few high-z candidates. Gravitational lensing by a foreground 
galaxy cluster can make sources easier to detect but also reduces the volume 
surveyed, limiting the chance of detection. We have shown that fields 
containing multiple cluster-scale halos in projection can increase the lensing 
cross section, allowing one to probe further down the luminosity function. We 
have identified lines-of-sight in the Sloan Digital Sky Survey with the 
highest densities of luminous red galaxies. Galaxy spectroscopy reveals that 
many contain multiple cluster-scale halos and larger integrated masses than 
even known lensing clusters. However, our derived mass models lack constraints 
on the shapes and concentrations of these halos, preventing a precise 
determination of the 2-D magnification map. We have already used Suprime-Cam 
to identify arcs and place constraints on the mass models in two beams. We 
propose imaging of two additional promising fields to identify multiply imaged 
sources at z ~ 1 - 3 and determine photometric redshifts, which will provide 
the necessary constraints and set the stage for measuring the faint-end 
luminosity function at z > 7.