THE NEXT GENERATION VIRGO CLUSTER SURVEY. XX. RedGOLD BACKGROUND GALAXY CLUSTER DETECTIONS

Abstract

ABSTRACT We build a background cluster candidate catalog from the Next Generation Virgo Cluster Survey (NGVS) using our detection algorithm RedGOLD. The NGVS covers 104 deg2 of the Virgo cluster in the -bandpasses to a depth of g ∼ 25.7 mag (5σ). Part of the survey was not covered or has shallow observations in the r band. We build two cluster catalogs: one using all bandpasses, for the fields with deep r-band observations (∼20 deg2), and the other using four bandpasses ( ) for the entire NGVS area. Based on our previous Canada–France–Hawaii Telescope Legacy Survey W1 studies, we estimate that both of our catalogs are ∼100% (∼70%) complete and ∼80% pure, at z ≤ 0.6 (z ≲ 1), for galaxy clusters with masses of M ≳ 1014 M ⊙. We show that when using four bandpasses, though the photometric redshift accuracy is lower, RedGOLD detects massive galaxy clusters up to z ∼ 1 with completeness and purity similar to the five-band case. This is achieved when taking into account the bias in the richness estimation, which is ∼40% lower at 0.5 ≤ z < 0.6 and ∼20% higher at 0.6 < z < 0.8, with respect to the five-band case. RedGOLD recovers all the X-ray clusters in the area with mass M 500 > 1.4 × 1014 M ⊙ and 0.08 < z < 0.5. Because of our different cluster richness limits and the NGVS depth, our catalogs reach lower masses than the published redMaPPer cluster catalog over the area, and we recover ∼90%–100% of its detections.