Galaxy cluster searches by photometric redshifts in the CFHTLS
  In order to enlarge publicly available optical cluster catalogs, in
particular at high redshift, we have performed a systematic search for clusters
of galaxies in the CFHTLS. We used the Le Phare photometric redshifts for the
galaxies detected with magnitude limits of i'=25 and 23 for the Deep and Wide
fields respectively. We then constructed galaxy density maps in photometric
redshift bins of 0.1 based on an adaptive kernel technique and detected
structures with SExtractor. In order to assess the validity of our cluster
detection rates, we applied a similar procedure to galaxies in Millennium
simulations. We measured the correlation function of our cluster candidates. We
analyzed large scale properties and substructures by applying a minimal
spanning tree algorithm both to our data and to the Millennium simulations. We
have detected 1200 candidate clusters with various masses (minimal masses
between 1.0 10$^{13}$ and 5.5 10$^{13}$ and mean masses between 1.3 10$^{14}$
and 12.6 10$^{14}$ M$_\odot$), thus notably increasing the number of known high
redshift cluster candidates. We found a correlation function for these objects
comparable to that obtained for high redshift cluster surveys. We also show
that the CFHTLS deep survey is able to trace the large scale structure of the
universe up to z$\geq$1. Our detections are fully consistent with those made in
various CFHTLS analyses with other methods. We now need accurate mass
determinations of these structures to constrain cosmological parameters.
