X-Ray Observations of RCS Clusters at High Redshift Erica Ellingson, U. Colorado Amalia Hicks, U. Colorado/ U. Virginia Mark Bautz, MIT Henk Hoekstra (U. Victoria) Mike Gladders, Carnegie Obs. Howard Yee, U. Toronto

The RCS Surveys Review by H. Yee earlier today: optically selected clusters via their red sequence RCS-1; 90 square degrees (completed) RCS-2: 1000 square degrees Z ~ 1 Still needed: calibration of cluster mass estimates for optically selected clusters

RCS Chandra Observations Chosen from the sample: 9 clusters (now 12) (0.64) 0.75< z< 1.1 Some initial emphasis on the most massive, lensing systems from the first available RCS catalogs; sample is becoming representative of rich systems ACIS exposures: (10) 30-90Ksec

Optical/Chandra Observations Z=0.78 Z=0.64

8 out of 9 detected with > 5 (2112-6326 at zph=1.1 is 2-3) 3 additional cluster detections on the way (final data arrived this week)

20ksec first exposure (more just arrived): Three new detections: z ~ 0.6-0.9

“Low Redshift” Comparisons 14 X-Ray selected CNOC (EMSS + Abell 2390) 0.17 < z < 0.55 Well determined masses via dynamics, lensing, Xrays (ROSAT +Chandra) 25% scatter XXXX vdMarel Carlberg, Yee & Ellingson 1997 van der Marel et al. 2000 Lewis et al. 1999 Hicks et al. 2005

Lensing Masses for CNOC Weak lensing comparisons at z=0.2-0.55 (with Henk Hoekstra) Slight systematic mass overestimate (10%) for weak lensing masses

Calibrating Optical Richness with X-ray properties Initial mass estimator for RCS is the optical richness from the survey data: Bgc CNOC: Good agreement with expected relationships: Bgc vs. ,Lx,Tx,M200 Yee & Ellingson 2003, updated for Chandra by Hicks, et al., 2005 Bgc well determined as a possible mass calibrator: dynamics, lensing Black: weak lensing shear composites (Hoekstra) Red: CNOC cluster dynamics

RCS: Lx-Bgc RCS clusters are under-luminous for their optical richness See also: Donahue et al. 99, Gilbank, 2004 Lubin et al., 2004 … XXX Sope=? L2500 CNOC, CF corrected : diamonds RCS: squares

Tx-Bgc Temperatures show general agreement with lower-z X-ray samples Slightly systematically lower temperature for their optical richnesses Outlier: superposition of groups in small z range (e.g., Gilbank’s talk, also Gonzales’ supergroup?): predicted to be ~5% of RCS? Note: 3 clusters NOT plotted Maybe one more in sample of 12 Diamonds= CNOC Squares = 6 RCS clusters with enough signal to measure Tx

Lx-Tx RCS: clusters underluminous for expected Tx? Large uncertainties… Solid: slope=2.2 Dotted = 2.0 Dashed= best fit slope 4+/- 2 See also Lubin, et al., 2004 0439 rejoins the sample clear we need more and better Tx’s, especially for richer clusters we’ve discovered as the sample has been completed. CNOC slope 2.2+- 0.3 Combined: 4+- 2, CNOC: diamonds RCS: squares

Redshift Evolution of Optical/X-ray mass estimates? Tx-Bgc is scaled by M200-Bgc-Tx relation to reduce to a mass ratio Evolution seen in X-ray-selected CNOC sample at z < 0.6? Mass ~ Bgc (1+z) = -0.5 +/- 0.5 Why? LF evolves differently- faster? Nope… Spatial distribution of galaxies such that Bgc measures larger fraction of galaxies OR evolution of optically-selected clusters- most likely Consistent with self-calibrating model for RCS (Majumdar, later today)

SZ detections BIMA/OVRO observations from Kyle Dawson & J. Carlstrom’s group 6 RCS clusters detected Agreement with X-ray results for Mtot and Mgas requires factor of 2 variation in gas fractions, consistent with lowered X-ray luminosities Gas fraction on the cores may explain some of it?

AGN in Clusters CNOC: excess of X-ray point sources in a few clusters…. Overall, no strong excess Straight line = expected background Histo = 2-8 keV point sources Ellingson et al. 2005

RCS: analysis just beginning RCS0224-002, z=0.78- regular, lensing cluster, possible small cooling core Excess of sources just inside the virial radius (see also Rudman & Ebeling 2005) Significant energy ejection by AGN? (e.g., talk by Donahue) Need to see if this is ubiquitous for all RCS clusters…

Conclusions RCS Clusters at z > 0.75 are X-ray sources- all detected “Contamination” by “super group” structures at ~zcluster 1 or 2 out of 12, also X-ray sources X-ray luminosities and gas fractions within R2500 scatter systematically low. Lx-Tx is not unreasonable- ?steeper? (large error bars!). Virialization of all components is required to produce uniform X-ray/optical relations. Tx-richness relation shows that red galaxies reliably indicate mass (not necessarily virialized). Relation shows some evolution, consistent with self-calibrating N(M,z) models. Further comparisons with dynamics, lensing (HST) , IR luminosity (Spitzer) are under way! Nothing terrifically surprising Contamination: Tx is factor of 2 lower than exected from Bgc