Galaxy cluster searches by photometric redshifts in the CFHTLS

TL;DR

This study systematically searches for galaxy clusters in the CFHTLS using photometric redshifts, resulting in a large catalog of high redshift candidates and demonstrating the survey's capability to trace large-scale structure up to z≥1.

Contribution

Introduces a new method combining photometric redshifts and adaptive kernel detection to identify galaxy clusters in CFHTLS data, significantly expanding high redshift cluster catalogs.

Findings

Detected 1200 galaxy cluster candidates with diverse masses.

Cluster correlation function comparable to other high redshift surveys.

CFHTLS deep survey effectively traces large-scale structure up to z≥1.

Abstract

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.