Radio Sources in High-Redshift Galaxy Clusters: An Initial Look Megan Roscioli University of Chicago In collaboration with Mike Gladders, U. Chicago RCS-1,2 Collaboration GLCW8, Columbus

Motivation We (finally) have large, well-characterized catalogs of clusters, so we should investigate the associated source populations at other wavelengths. What is the relation between AGN (and heating from AGN) and the formation/characteristics of BCGs and other cluster members? How significantly will radio point sources contaminate upcoming SZ surveys? How significantly do AGN contribute to the energy budget of clusters? Can heating from radio lobes of AGN provide enough energy into the ICM to counter cooling flows?

Outline: Cluster samples: RCS-1, RCS-2, details Radio source samples: FIRST, NVSS Radial distribution Radio luminosity dependence Cluster richness dependence Evolution with redshift

Data - optical RCS-1  two-band (R C and z’) optical survey at CFHT and CTIO uses red sequence cluster finding methods  well-defined sub-sample of ~ 1,000 clusters (see Gladders, et al. 2007)  significance > 3.3  0.35 < z < 0.95  red galaxy richness > 300  richness errors < 50%  Near-complete to redshifts ~ 0.95 Reference: Gladders & Yee, 2005 NOAO/AURA/NSF

Data - optical RCS-2 (  three-band (grz) optical survey at CFHT using Megacam. Uses red sequence cluster finding methods  Survey ongoing: data acquisition completion planned end of 2007  Current cluster sample is ~30,000 clusters …and more on the way!

Data - radio NVSS  VLA compact D and DnC configurations, 1.4 GHz resolution ~ 45”  All-sky above -40 degrees declination  sensitivity limit ~ 2.5 mJy FIRST  VLA B-array, 1.4 GHz resolution ~ 5”  10,000 square degrees  sensitivity limit ~ 1.0 mJy Reference: Condon, et al References: Becker, White & Helfand 1995 White, et al Image courtesy of NRAO/

Combined Overlap Areas RCS-2+NVSS ~414 square degrees Pros: large area, many clusters, many radio sources Cons: Cluster catalog not yet fully characterized RCS-1+FIRST ~40 square degrees Pros: well characterized cluster sample with established cosmological context Cons: much smaller sample

AGN profiles Optical/Radio X-ray Ruderman & Ebeling, 2005

Radio Luminosity bins

Significance bins

Evolution with redshift RCS1+FIRST: Number of FIRST sources/cluster: for 0.3 < z < / for 0.65 < z < / discernible 40% increase in radio sources per cluster at high redshift

Where next? Scale radial distribution of radio sources to virial radius (R 200 ) Consider radio morphology Calculate the radial distribution of radio sources around cluster BCGs Push to higher frequencies?

Summary of preliminary results We detect a significant association between NVSS and FIRST sources and RCS clusters over the entire RCS redshift range. Source numbers are sufficient to explore sample characteristics over a broad range of properties  Radial distribution: radio sources most obviously found within the central few hundred kpc.  Radial distribution: some evidence for source excess at ~1-2 Mpc  The highest luminosity radio sources avoid cluster centers relative to lower luminosity sources  More “massive” clusters contain more radio sources  Discernible 40% increase at high redshifts in the number of radio sources in clusters And more to come!