Investigating emission-line galaxy surveys with the Sloan Digital Sky Survey infrastructure

The baryon acoustic oscillation (BAO) feature in the power spectrum of galaxies provides a standard ruler to probe the accelerated expansion of the Universe. The current surveys covering a comoving volume sufficient to unveil the BAO scale are limited to redshift z less than or similar to 0.7. In this paper, we study several galaxy selection schemes aiming at building an emission-line galaxy (ELG) sample in the redshift range 0.6 < z < 1.7 that would be suitable for future BAO studies using the Baryonic Oscillation Spectroscopic Survey (BOSS) spectrograph on the Sloan Digital Sky Survey (SDSS) telescope. We explore two different colour selections using both the SDSS and the Canada-France-Hawaii Telescope Legacy Survey (CFHT-LS) photometry in the u, g, r and i bands and evaluate their performance selecting luminous ELGs. From about 2000 ELGs, we identified a selection scheme that has a 75 per cent redshift measurement efficiency. This result confirms the feasibility of massive ELG surveys using the BOSS spectrograph on the SDSS telescope for a BAO detection at z similar to 1, in particular the proposed eBOSS experiment, which plans to use the SDSS telescope to combine the use of the BAO ruler with redshift space distortions using ELGs and quasars in the redshift range 0.6 < z < 2.2.