Cluster Catalogs from 161 deg 2 of CFHTLS-Wide gri imaging Karun Thanjavur Supervisors:Dr. David Crampton, HIA/ UVic Dr. Jon Willis, UVic SL2S Meeting, Marseilles, 11 May 2009

Cluster Catalogs from 161 deg 2 of CFHTLS-Wide gri imaging Objective: Build a catalog of confirmed lensed, emission line galaxies suitable for IFU observations (  redshift interval, z ≤ 1.5, surface brightness,  i ≤ 22.5 mag/arc.sec 2 ) 3-step approach: 1. Detect galaxy groups and clusters with an automated search 2. Identify lensed arc features around each detected group or cluster 3. Confirm with longslit or multi-object spectroscopy. Methodology: Automated method designed to work with available g, r and i filters imaging in the CFHTLS-Wide survey (using Terapix T05 photometric catalogs)

K2, an automated galaxy group and cluster detector (Method targets the population of early type galaxies in the cluster core using density enhancements in position and colors ) Clustering in position Clustering in color

Tests bright galaxies in Terapix T05 catalogs for cluster membership ãUses available Terapix T05 g, r and i photometric catalogs for each square degree of CFHTLS-Wide fields. ãTests each bright galaxy, (BG, 16 ≤ i’ ≤ 20mag) for cluster membership (~2000 BG and 175,000 field objects in each square degree)

 For each BG, obtains positions and colors of all galaxies within a pre-defined aperture (diameter 1h -1 Mpc at z=0.5) and within a pre-defined color cut (±0.15mag of BG color) ãUsing the relative differences, , between the selected galaxies and BG in position and in (g-r) and (r-i) colors, compute the metric of overdensity (referred as the cluster weight, W c Cluster weight = metric of position + color overdensity

Compute field weight and detection significance  Place the BG at 100 random positions in the field, and compute the metric of field overdensity, measured by W f and  f (mean and standard deviation of the 100 trials)  Compute the detection significance, S, for each BG by comparing the cluster vis-à-vis field metric values in each color ( >3   candidate cluster member) W c and W f = cluster and field metrics of overdensity;  f = statistical spread in field metric

 Classify candidate cluster members into Gold ( >5  in both colors), Silver ( >5  in one color, >3  in the other), and Bronze ( >3  in both colors) categories  Link all identified members, which lie within an aperture radius of each other and within the color cuts, as members of a candidate cluster  Determine properties for candidate clusters, (number of members, Abell richness and photometric redshift, where five filter imaging is available)  write to cluster catalogs for each field Linking and classification of cluster candidates

False detection rate 1-2%, for a selection significance threshold of 3  Complete to 80% for Coma-like clusters up to z=0.8, to z=0.6 for Fornax-like and z=0.3 for a poor (WBL) cluster Calibration of K2 using Monte-Carlo simulations for contamination and completeness Test the recovery of a synthetic cluster from a random position within a field galaxy population. Properties of clusters and field galaxies generated using published observational results

Characterization of K2 cluster candidates by comparison with published cluster catalogs XMM-LSS and the Matched Filter cluster catalogs for the CFHTLS-D1 12 of the 17 XMM-LSS clusters in D1 also detected by our method. All XMM-LSS clusters at z < 0.8 are detected, matching the Monte- Carlo results. All MF Class-A clusters at z < 0.8 detected by our method Non-detections lie at higher redshifts An example of a XMM-LSS cluster also detected by K2 ; the red square marks the center of X-ray emission, while the detected BCG is marked by the blue cross.

K2 candidates from 161 deg 2 of CFHTLS-W imaging with significances above detection threshold in each color Histograms showing detection significances of candidate cluster members in the (g-r) and (r-i) colors Gold = 5  detection in (g-r) and (r-i); Silver = 5  in one, 3  in the other; Bronze = 3  in both colors

Histograms showing gold, silver and bronze candidates in each field. K2 candidates from 161 deg 2 of CFHTLS-W imaging Breakdown by Gold, Silver and Bronze classes

Histograms showing Abell richness classes of candidates in each field W = Richness -1 (group-scale) ; F = Richness 0 (Fornax-like) ; C = Richness 1 or higher (Coma-like) K2 candidates from 161 deg 2 of CFHTLS-W imaging Breakdown by Abell Richness classes

SL2S cluster lens detected as a Gold candidate by K2 (Detected BCG and cluster members indicated in red)