The RedGOLD Cluster Detection Algorithm and its Cluster Candidate Catalogue for the CFHT-LS W1

Abstract

RedGOLD searches for red-sequence galaxy overdensities while minimizing contamination from dusty star-forming galaxies. It imposes an NFW profile and calculates cluster detection significance and richness. We optimize these latter two parameters using both simulations and X-ray detected cluster catalogs, and obtain a catalog $\sim 80\%$ pure up to $z\sim 1$, and $\sim 100\%$ ($\sim 70\%$) complete at $z\le 0.6$ ( $z\lesssim 1$) for galaxy clusters with $M\gtrsim 10^{14}{\mathrm{M}}_{\odot }$ at the CFHT-LS Wide depth. In the CFHT-LS W1, we detect 11 cluster candidates per $\mathrm{de}{\mathrm{g}}^2$ out to $z\sim 1.1$. When we optimize both completeness and purity, RedGOLD obtains a cluster catalog with higher completeness and purity than other public catalogs, obtained using CFHT-LS W1 observations, for $M\gtrsim 10^{14}{\mathrm{M}}_{\odot }$. We use X-ray detected cluster samples to extend the study of the X-ray temperature-optical richness relation to a lower mass threshold, and find a mass scatter at fixed richness of ${\sigma }_{lnM|\lambda }=0.39\pm 0.07$ and ${\sigma }_{lnM|\lambda }=0.30\pm 0.13$ for the Gozaliasl et al. (2014) and Mehrtens et al. (2012) samples. When considering similar mass ranges as previous work, we recover a smaller scatter in mass at fixed richness. We recover $93\%$ of the redMaPPer detections, and find that its richness estimates is on average $\sim 40-50\%$ larger than ours at $z>0.3$. RedGOLD recovers X-ray cluster spectroscopic redshifts at better than $5\%$ up to $z\sim 1$, and the centers within a few tens of arcseconds.

Licitra et al. 2016, MNRAS, 455, 3020 Our catalogs are planned to be available on ADS