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A 10 deg^2 Lyman α survey at z=8.8 with spectroscopic follow-up : strong constraints on the luminosity function and implications for other surveys.

Matthee, J.J.A. and Sobral, D. and Swinbank, A.M. and Smail, I. and Best, P.N. and Kim, J.-W. and Franx, M. and Milvang-Jensen, B. and Fynbo, J. (2014) 'A 10 deg^2 Lyman α survey at z=8.8 with spectroscopic follow-up : strong constraints on the luminosity function and implications for other surveys.', Monthly notices of the Royal Astronomical Society., 440 (3). pp. 2375-2387.


Candidate galaxies at redshifts of z ∼ 10 are now being found in extremely deep surveys, probing very small areas. As a consequence, candidates are very faint, making spectroscopic confirmation practically impossible. In order to overcome such limitations, we have undertaken the CF-HiZELS survey, which is a large-area, medium-depth near-infrared narrow-band survey targeted at z = 8.8 Lyman α (Lyα) emitters (LAEs) and covering 10 deg2 in part of the SSA22 field with the Canada–France–Hawaii Telescope (CFHT). We surveyed a comoving volume of 4.7 × 106 Mpc3 to a Lyα luminosity limit of 6.3 × 1043 erg s−1. We look for Lyα candidates by applying the following criteria: (i) clear emission-line source, (ii) no optical detections (ugriz from CFHTLS), (iii) no visible detection in the optical stack (ugriz > 27), (iv) visually checked reliable NBJ and J detections and (v) J − K ≤ 0. We compute photometric redshifts and remove a significant amount of dusty lower redshift line-emitters at z ∼ 1.4 or 2.2. A total of 13 Lyα candidates were found, of which two are marked as strong candidates, but the majority have very weak constraints on their spectral energy distributions. Using follow-up observations with SINFONI/VLT, we are able to exclude the most robust candidates as LAEs. We put a strong constraint on the Lyα luminosity function at z ∼ 9 and make realistic predictions for ongoing and future surveys. Our results show that surveys for the highest redshift LAEs are susceptible of multiple contaminations and that spectroscopic follow-up is absolutely necessary.

Item Type:Article
Keywords:Galaxies: evolution, Galaxies: high-redshift, Cosmology: observations, Dark ages, Reionization, First stars.
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Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2013 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.
Date accepted:26 February 2014
Date deposited:20 June 2014
Date of first online publication:May 2014
Date first made open access:No date available

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