Brightest X-Ray Clusters of Galaxies in the CFHTLS Wide Fields: Catalog and Optical Mass Estimator

Abstract

The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) presents a unique data set for weak-lensing studies, having high-quality imaging and deep multiband photometry. We have initiated an XMM-CFHTLS project to provide X-ray observations of the brightest X-ray-selected clusters within the wide CFHTLS area. Performance of these observations and the high quality of CFHTLS data allow us to revisit the identification of X-ray sources, introducing automated reproducible algorithms, based on the multicolor red sequence finder. We have also introduced a new optical mass proxy. We provide the calibration of the red sequence observed in the Canada-France-Hawaii filters and compare the results with the traditional single-color red sequence and photo-z. We test the identification algorithm on the subset of highly significant XMM clusters and identify 100% of the sample. We find that the integrated z-band luminosity of the red sequence galaxies correlates well with the X-ray luminosity, with a surprisingly small scatter of 0.20 dex. We further use the multicolor red sequence to reduce spurious detections in the full XMM and ROSAT All-Sky Survey (RASS) data sets, resulting in catalogs of 196 and 32 clusters, respectively. We made spectroscopic follow-up observations of some of these systems with HECTOSPEC and in combination with BOSS DR9 data. We also describe the modifications needed to the source detection algorithm in order to maintain high purity of extended sources in the shallow X-ray data. We also present the scaling relation between X-ray luminosity and velocity dispersion.

Evolution of the cluster optical galaxy luminosity function in the CFHTLS: breaking the degeneracy between mass and redshift

“…In the following sections, we will compare our candidate cluster catalogue to previously published cluster catalogues on the Wide fields of CFHTLS. We will first make a comparison with other optically detected cluster candidate catalogues from Licitra et al (2016) and Ford et al (2015), and with Xray detected cluster catalogues from Gozaliasl et al (2014) and Mirkazemi et al (2015).…”

“…We also compare our candidate cluster catalogue with two X-ray detected cluster catalogues provided by Gozaliasl et al (2014) and Mirkazemi et al (2015), both obtained from XXM-Newton observations. The Gozaliasl et al (2014) catalogue covers an area of 3 deg 2 inside the CFHTLS W1 field and includes 135 X-ray detected groups and clusters up to z = 1.1, while the Mirkazemi et al (2015) catalogue was built by pointing at given optically selected cluster candidates; it includes 196 X-ray detected groups and clusters up to z = 1.1 in the CFHTLS W1, W2, and W4.…”

“…The Gozaliasl et al (2014) catalogue covers an area of 3 deg 2 inside the CFHTLS W1 field and includes 135 X-ray detected groups and clusters up to z = 1.1, while the Mirkazemi et al (2015) catalogue was built by pointing at given optically selected cluster candidates; it includes 196 X-ray detected groups and clusters up to z = 1.1 in the CFHTLS W1, W2, and W4.…”

“…However, neither Gozaliasl et al (2014) nor Mirkazemi et al (2015) provide the completeness of their catalogue for given mass and redshift. Thus they cannot be used to properly compute a selection function of our algorithm, but only give us insights into how AMASCFI performed on the CFHTLS T0007 data.…”

“…We detect a total of 3743 cluster candidates up to redshift z ∼ 1.1 and estimate the selection function of this sample by applying the same algorithm to numerical simulations based on lightcones from the Millennium simulation by Springel et al (2005) and modified by Henriques et al (2012). We derive a mass for each cluster candidate using a richness-mass relation calibrated on the X-ray clusters of Gozaliasl et al (2014) and Mirkazemi et al (2015) that are also detected by our algorithm. We compute cluster GLFs for all galaxies, and also for early and late types separately.…”