The ultracool field dwarfs luminosity function from the Canada-France Brown Dwarf Survey

Abstract

The Canada‐France Brown Dwarf Survey is a wide field survey for cool brown dwarfs conducted with the MegaCam camera on the CFHT telescope. Our objectives are to find ultracool brown dwarfs and to constrain the field brown dwarf mass function from a large and homogeneous sample of L and T dwarfs. We identify candidates in CFHT/Megacam i’ and z’ images and follow them up with pointed NIR imaging on several telescopes. Our survey has to date found 50 T dwarfs candidates and 170 L or late M dwarf candidates drawn from a larger sample of 1300 candidates with typical ultracool dwarfs i’‐z’ colours, found in 900 square degrees. We currently have completed the NIR follow‐up on a large part of the survey for all candidates from the latest T dwarfs known to the late L color range. This allows us to build on a complete and well defined sample of ultracool dwarfs to investigate the luminosity function of field L and T dwarfs.