NOAO >   Observing Info >   Approved Programs >   2012A-0052

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Proposal Information for 2012A-0052


PI: Jason Xavier Prochaska, UCO Lick Observatory/UCSC, xavier@ucolick.org
Address: Astronomy Department, 1560 High St., Santa Cruz, CA 95064, USA

CoI: Robert da Silva, UC Santa Cruz
CoI: Adam Meyers, University of Wyoming
CoI: Joseph Hennawi, Max Planck Institute for Astronomy
CoI: Gabriele Maier, Max Planck Institute for Astronomy

Title: Quasars Probing Quasars: New Constraints on the Quasar Phenomenon from the Transverse Proximity Effect

Abstract: We have mined the SDSS and discovered a large sample of projected pairs of quasars at z=2 - 4 with sub-arcminute angular separations. In these unique sightlines, \lya absorption in the \emphbackground quasar spectrum, encodes information about the \emphforeground quasars environment, emission geometry, and radiative history, provided that its systemic redshift is known accurately. Continuing on our successful 2011B allocation, we propose to use TripleSpec to obtain near-IR spectra of 16 additional foreground quasars to determine precise (\sigma_\rm z ~eq 40 km/s) redshifts from rest-frame optical emission lines which trace the systemic frame. This will eliminate the current ~ 8 \rm Mpc uncertainty in the foreground quasars' radial position, resolving transverse scales as small as 50 \kpc. These measurements will enable us to robustly characterize the \emphtransverse proximity effect for the first time, which will constrain the fraction of high redshift quasars which are obscured and determine whether quasars vary significantly on ~ 10^5-10^6 \rm yr timescales. This request will complete our highest priority sample in the Northern sky.


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