Astronomy Tea Talk

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 among multiple halos, as well as which physical properties of the halos are most important. We find that multiple projected halos are can result in improvement in the detection of faint, high-z sources compared to single halos of equivalent total mass due to the interactions among the lensing potentials when the projected halos overlap. Using integrated LRG luminosity density as a tracer of mass, we have identified lines of sight in the SDSS that are likely to contain the largest total integrated masses. These fields contain a diversity of single massive clusters and chance alignments of multiple halos in projection, and are likely to be among the best gravitational lenses known.