EMITTING AND Lyα ABSORBING GALAXIES

The spectral properties of Lyman break galaxies (LBGs) offer a means to isolate pure samples displaying either dominant Lyα in absorption or Lyα in emission using broadband information alone. We present criteria developed using a large z ∼ 3 LBG spectroscopic sample from the literature that enables large numbers of each spectral type to be gathered in photometric data, providing good statistics for multiple applications. In addition, we find that the truncated faint, blue-end tail of z ∼ 3 LBG population overlaps and leads directly into an expected Lyα emitter (LAE) population. As a result, we present simple criteria to cleanly select large numbers of z ∼ 3 LAEs in deep broadband surveys. We present the spectroscopic results of 32 r . 25.5 LBGs and r . 27.0 LAEs at z ∼ 3 pre-selected in the Canada-France-Hawaii Telescope Legacy Survey that confirm these criteria. Subject headings: galaxies: evolution — galaxies: formation — galaxies: fundamental parameters — galaxies: photometry