Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results
Abstract
We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to find ultracool brown dwarfs and to constrain the field-brown dwarf mass function thanks to a larger sample of L and T dwarfs. We identify candidates in CFHT/MegaCam i' and z' images using optimised psf-fitting within Source Extractor, and follow them up with pointed near-infrared imaging on several telescopes. We have so far analysed over 350 square degrees and found 770 brown dwarf candidates brighter than z'{AB}=22.5. We currently have J-band photometry for 220 of these candidates, which confirms 37% as potential L or T dwarfs. Some are among the reddest and farthest brown dwarfs currently known, including an independent identification of the recently published ULAS J003402.77-005206.7 and the discovery of a second brown dwarf later than T8, CFBDS J005910.83-011401.3. Infrared spectra of three T dwarf candidates confirm their nature, and validate the selection process. The completed survey will discover ~100 T dwarfs and ~500 L dwarfs or M dwarfs later than M8, approximately doubling the number of currently known brown dwarfs. The resulting sample will have a very well-defined selection function, and will therefore produce a very clean luminosity function.
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Cite
@article{arxiv.0804.1477,
title = {Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results},
author = {Philippe Delorme and Chris J. Willott and Thierry Forveille and Xavier Delfosse and Céline Reylé and Emmanuel Bertin and Loic Albert and Etienne Artigau and Annie C. Robin and France Allard and Rene Doyon and Gary J. Hill},
journal= {arXiv preprint arXiv:0804.1477},
year = {2009}
}
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