Radio Sources in High-Redshift Galaxy Clusters: An Initial Look

1. 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

2. 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?

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

4. Data - optical NOAO/AURA/NSF • RCS-1 • two-band (RC 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

5. Data - optical • RCS-2 (www.rcs2.org) • 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!

6. 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. 1998 References: Becker, White & Helfand 1995 White, et al. 1997 Image courtesy of NRAO/

7. 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

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

11. Radio Luminosity bins

12. Significance bins

13. Evolution with redshift RCS1+FIRST: Number of FIRST sources/cluster: for 0.3 < z < 0.65 0.067 +/- 0.010 for 0.65 < z < 0.95 0.094 +/- 0.014 discernible 40% increase in radio sources per cluster at high redshift

14. Where next? • Scale radial distribution of radio sources to virial radius (R200) • Consider radio morphology • Calculate the radial distribution of radio sources around cluster BCGs • Push to higher frequencies?

15. 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!