A 10 deg2 Lyman-α survey at z = 8.8 with spectroscopic follow-up: strong constraints on the LF and implications for other surveys?

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 under-taken 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. 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 candi-dates 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 6 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 SEDs. Using follow-up observations with SIN-FONI/VLT we are able to exclude the most robust candidates as Lyα emitters. We put a stron