The WIRCam Deep Survey I: Counts, colours and mass-functions derived from near-infrared imaging in the CFHTLS Deep Fields

Abstract

We present a new near-infrared imaging survey in the four CFHTLS deep fields: the WIRCam Deep Survey or _s15WIRDS_s15. WIRDS comprises extremely deep, high quality (FWHM approx 0.6_s15) J, H and Ks imaging covering a total effective area of 2.1 square degrees and reaching AB 50% completeness limits of approx 24.5. We combine our images with the CFHTLS to create a unique eight-band ugrizJHKS photometric catalogues in the four CFHTLS deep fields_s19 these four separate fields allow us to make a robust estimate of the effect of cosmic variance for all our measurements. We use these catalogues in combination with approx 9,800 spectroscopic redshifts to estimate precise photometric redshifts ({sigma} < 0.03), galaxy types, star-formation rates and stellar masses for a unique sample of approx 1.8 million galaxies. Our JHKs number counts are consistent with previous studies. We apply the _s15BzK_s15 selection to our gzK filter set and find that the star forming BzK selection successfully selects 76% of star-forming galaxies in the redshift range 1.4 < z < 2.5 in our photometric catalogue, based on our photometric redshift measurement. Similarly the passive BzK selection returns 52% of the passive 1.4 < z < 2.5 population identified in the photometric catalogue. We present the mass functions of the total galaxy population as a function of redshift up to z = 2. We show that the GALFORM semi-analytical galaxy formation model can produce a consistent match to the observed mass functions across the mass range log(M/Modot) sim 10-11 up to redshifts of z sim 1.2 - 1.5. All photometric catalogues and images are made publicly available from TERAPIX and CADC.