Ken Wong (Arizona)
Optimal Mass Configurations for Lensing High-Redshift Galaxies
We investigate whether lines of sight containing multiple cluster-scale halos are the best cosmic telescopes for lensing high-redshift (z ~ 10) sources into detectability. For lines of sight of fixed angular size and total mass, we test how the lensing cross section and the number of faint galaxies detected at high redshift change as that mass is distributed from one to two, three, and five halos. We also test which halo properties - projected separation, concentration, halo mass ratio, halo ellipticity - most affect the lensing cross section. We find that multiple projected halos are generally better lenses than single halos of equivalent total mass due to the interactions among the lensing potentials when the projected halos overlap. This effect can be comparable to increasing the total mass of the lens from 10^15 M_sun to 3x10^15 M_sun. Splitting the mass into multiple halos and optimizing their separations and concentrations generally improves the lens and can lead to a significant improvement in the detection of faint, high-z sources. We have now identified such lines of sight in the SDSS.