White dwarfs in the CFHTLS Deep fields

ABSTRACT

We present an initial assessment of white dwarfs in the third data release of the Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) Deep fields. Following the morphological classification of point sources, we have selected the white dwarf candidates through colour cuts. A detailed comparison between the observed colours of the selected point sources with the expected colours of white dwarfs and quasars reveal 28 white dwarf candidates with T_eff≥ 5500 K. Eight of these candidates are spectroscopically confirmed to be white dwarfs, which demonstrates that our selection process is robust. Even though the i-band limiting magnitude of the Deep fields is  i∼ 26 mag , we find that the star–galaxy separation is not reliable for  i > 21 . Using spectroscopic data from the VLT–VIRMOS Deep Survey, we quantify the contamination of our stellar sample by quasars and galaxies. Our catalogue of white dwarfs is incomplete, and further studies of the population of white dwarfs in the CFHTLS require accurate proper-motion measurements.