Lyα emitters with red colors at z ≃ 2.4

We have carried out a search for Lyα emission from galaxies at z ≃ 2.4 over a field of 1200 arcmin² using the CFH12K camera at the Canada-France-Hawaii Telescope and a custom medium-band filter. The search has uncovered 58 candidates, corresponding to a completeness-corrected source density of ∼0.07 arcmin^-2. Our sources have red colors (B - I ≃ 1.8) that imply either that a large fraction of the light is highly reddened and that we are detecting Lyα emission through special lines of sight or that these objects contain an underlying older stellar population. While for each individual object we cannot discriminate between these alternatives, we conclude that most of the objects actually contain an older component because the star formation rates inferred from the picture based on reddening, applied to all candidates, would imply an exceedingly high star formation rate, i.e., more than 2 orders of magnitude above the peak cosmic star formation rate.