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First results from the Canada-France High-z Quasar Survey: Constraints on the z=6 quasar luminosity function and the quasar contribution to reionization

Chris J. Willott·Xavier Delfosse·Thierry Forveille·Philippe Delorme·Stephen D. J. Gwyn
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Abstract

We present preliminary results of a new quasar survey being undertaken with multi-colour optical imaging from the Canada-France-Hawaii Telescope. The current data consists of 3.83 sq. deg. of imaging in the i' and z' filters to a 10 sigma limit of z'<23.35. Near-infrared photometry of 24 candidate 5.7 -3.2 at 95% confidence. We find that the comoving space-density of quasars brighter than M_1450=-23.5 declines by a factor >25 from z=2 to z=6, mirroring the decline observed for high-luminosity quasars. We consider the contribution of the quasar population to the ionizing photon density at z=6 and the implications for reionization. We show that the current constraints on the quasar population give an ionizing photon density <<30% that of the star-forming galaxy population. We conclude that active galactic nuclei make a negligible contribution to the reionization of hydrogen at z~6.

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Chris J. Willott, Xavier Delfosse, Thierry Forveille, Philippe Delorme, Stephen D. J. Gwyn. 2005-07-07. First results from the Canada-France High-z Quasar Survey: Constraints on the z=6 quasar luminosity function and the quasar contribution to reionization. https://doi.org/10.1086/462408

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