The Local Space Density of Optically-Selected Clusters of Galaxies

Abstract

Abridged] We present here new results on the space density of rich, optically-selected, clusters of galaxies at low redshift (z<0.15). These results are based on the application of the matched filter cluster-finding algorithm to 1067 deg2 of the Edinburgh/Durham Southern Galaxy Catalogue (EDSGC). This is the first major application of this methodology at low redshift and in total, we have detected 2109 clusters above a richness cut-off of R_m >= 50 (or Lambda_cl >= 10). We have used extensive Monte Carlo simulations to define the detection thresholds for our algorithm, to measure the effective area of the EDCCII and to determine our spurious detection rate. These simulations have shown that our detection efficiency is strongly correlated with the presence of large-scale structure in the EDSGC data which we believe is due to the assumption of a flat, uniform background. Using these simulations, we are able to compute the space density of clusters in this new survey. We find 83.5 10-6 h-3 Mpc-3 for 100<= R_m < 200 (Lambda_cl~20) systems, 10.1 10-6 h-3 Mpc-3 for 200 <= R_m < 400 (Lambda_cl~40) systems and 2.3 10-6 h-3 Mpc-3 for R_m > 400 (Lambda_cl > 80) systems. These three richness bands roughly correspond to Abell Richness Classes 0, 1 and >=2 respectfully. These new measurements of the local space density of clusters are in agreement with those found at higher redshift (0.2 < z_est < 0.6) in the Palomar Distant Cluster Survey (PDCS; Postman et al. 1996 & Holden et al. 1999) thus confirming that the space density of clusters remains nearly constant out to z~0.6 in agreement with previous optical and X-ray measurements of the space density of clusters.

11 pages, 4 figures (emulateapj.sty). Accepted for publication by ApJ

References in corpus (4)

• The WARPS survey: III. The discovery of an X-ray luminous galaxy cluster at z=0.833 and the impact of X-ray substructure on cluster abundance measurements
• The Northern Sky Optical Cluster Survey I: Detection of Galaxy Clusters in DPOSS
• The Bright SHARC Survey: The X-ray Cluster Luminosity Function
• Spectroscopic Observations of Optically Selected Clusters of Galaxies from the Palomar Distant Cluster Survey

Cited by in corpus (13)

• A New Method For Galaxy Cluster Detection I: The Algorithm
• The Red-Sequence Cluster Survey I: The Survey and Cluster Catalogs for Patches RCS0926+37 and RCS1327+29
• The Cut & Enhance method : selecting clusters of galaxies from the SDSS commissioning data
• Galaxy clusters identified from the SDSS DR6 and their properties
• Detecting Clusters of Galaxies in the Sloan Digital Sky Survey I : Monte Carlo Comparison of Cluster Detection Algorithms
• The Northern Sky Optical Cluster Survey II: An Objective Cluster Catalog for 5800 Square Degrees
• A Deep Halpha Survey of Galaxies in the Two Nearby Clusters Abell1367 and Coma: The Halpha Luminosity Functions
• The KPNO/Deeprange Distant Cluster Survey: I. The Catalog & the Space Density of Intermediate Redshift Clusters
• The UV luminosity function and star formation rate of the Coma cluster
• Alignment of Brightest Cluster Galaxies with their Host Clusters
• The Mass-Dependent Clustering History of K-selected Galaxies at z < 4 in the SXDS/UDS Field
• The DPOSS II distant compact group survey: the EMMI-NTT spectroscopic sample
• CFHT Optical PDCS Survey II: Evolution in the Space Density of Clusters of Galaxies