NOAO >   Observing Info >   Approved Programs >   2002B-0292

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Proposal Information for 2002B-0292


PI: Patrick Hall, Princeton University / P. U. Catolica de Chile, pathall@astro.princeton.edu
Address: Peyton Hall, Ivy Lane, Princeton, NJ 08544-1001, USA

CoI: Mike Gladders, OCIW
CoI: Howard Yee, U. of Toronto

Title: Infrared Confirmation of z>5.5 Quasar Candidates

Abstract: A Gunn-Peterson trough (neutral hydrogen absorption) has been discovered in the spectrum of a z=6.28 quasar from the Sloan Digital Sky Survey. The lack of such troughs in the four other known z>5.5 quasars suggests that z~6 could be the tail end of the reionization epoch, when the spheres of ionized hydrogen around quasars and star- forming galaxies finally overlap. To better determine the timescale over which reionization occurred - and how the distribution of neutral hydrogen evolved during that epoch - requires more quasars at z>5.5. We have in hand 90 deg^2 of CFHT and CTIO Rz imaging which enables us to select candidate z>5.5 quasars and L/T type stars and brown dwarfs as objects with very red (R-z)_AB colors. Here we propose KPNO near-IR imaging to efficiently and accurately separate the quasars among our equatorial and northern candidates from the more numerous L and T dwarfs %class stars and brown dwarfs (which are scientifically interesting in their own right). Our survey reaches two magnitudes fainter than the SDSS, providing a tighter constraint on the quasar contribution to the UV flux needed for reionization (and enabling the discovery of more distant L and T dwarfs). The surface density of z>5.5 quasars is estimated to be 0.1 deg^-2 %unknown in the 20<z_AB<22 magnitude range of our survey, but could be as high as 1 deg^-2.


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