Exploring Non-Gravitational Heating through SZ Observations

1. Evidence for non-gravitational heating from SZ observations Ian McCarthy, Arif Babul (University of Victoria) Gil Holder (IAS) Michael Balogh (University of Durham) McCarthy, Holder, Babul & Balogh 2003, ApJ, submitted (theory paper) McCarthy, Babul, Holder & Balogh 2003, ApJ, submitted (comparison with data)

2. Introduction • X-ray luminosities, temperatures indicate non-gravitational processes at work • Observations suggest the presence of an entropy floor ranging from 100-400 keV cm2 • Lx  r2 implies these results are very sensitive to central, dense regions where cooling is important • Difficult at high redshift, because of (1+z)4 dimming

3. Sunyaev-Zeldovich Effect ∫Pe(r) dl y(q)= Pe = n kT Sn(q) = 2pjn(x) ∫ y(q') q' dq' x=hn/kTCMB SZ decrement does not suffer from SB dimming Correlate yo, Sn(1'), M500, LX, TX

4. Isothermal Models • Assume isothermal gas traces dark matter • Known to overpredict X-ray luminosity Preheated Models • Model of Babul et al. (2002) and Balogh et al. (1999) • Assumes gas preheated to uniform entropy; no cooling • Match observed M-T, L-T relations with K0=350 keV cm2 Fit power laws to SZ and X-ray variables, as explicit function of K0 and z

5. M=1015 M0 Isothermal model K0=400 keV cm2

6. Babul et al. 2001 10 kT [keV] 1 0.1 40 42 44 46 log10 LX [ergs s-1]

7. M = 3.2x1014 M0 Isothermal model K0=400 keV cm2 McCarthy et al. 2003a

8. M = 1.8x1015 M0 Isothermal model K0=400 keV cm2 McCarthy et al. 2003a

9. McCarthy et al. .2003a K0=400 keV cm2 Isothermal model

10. McCarthy et al. .2003a z=0 z=1

11. SZ Data Published data for ~40 clusters, from: • Berkeley Maryland Illinois Association (BIMA) • Owens Valley Radio Observatory (OVRO) • Ryle Telescope Plus future considerations: Sunyaev-Zeldovich Array (SZA) Upgraded OVRO array

12. SZ Cluster Sample 0.14 < Z < 0.3 Z > 0.3 *Shape parameters determined solely from X-ray profile †No shape profile information available

13. Extracting The Data: Part I • Want to measure yo and Sn(1') • yo requires extrapolating a model, while Sn can be affected by large-scale filtering • for BIMA, OVRO and Ryle, the highest resolution is typically smaller than the core radius (30″) and large-scale filtering is important for q>2'.

14. Extracting the Data: Part II • modelled assuming spherical, isothermal b model: y(q) = yo (1+q2/qc2)1/2-3b/2 • In general, not possible to constrain all three parameters (yo, b, qc) from SZ data alone • Reese et al. (2002) use joint maximum-likelihood analysis of both SZ and X-ray data

15. Babul et al. model ▲ Cooling flow ■ Non-cooling flow White: z<0.3 Blue: z>0.3 K0=540 keV cm2 Isothermal model McCarthy et al. 2003b

16. Babul et al. model ▲ Cooling flow ■ Non-cooling flow White: z<0.3 Blue: z>0.3 K0=570 keV cm2 Isothermal model McCarthy et al. 2003b

17. Consider 4 scaling relations: 1. Sn-y0K0=540 2. y0-TX K0=300 3. y0-M500 K0=500 4. Sn-LX K0=310 Sn-y0 relation y0-TX relation McCarthy et al. 2003b

18. The Future: SZA and OVRO • Would like to determine b and qc directly from SZ. This is necessary for high z • will have amplifiers operating at 26-36 GHz and 85-115 GHz • FWHM BIMA/OVRO/SZA = (6.6,4.2,10.8 arcmin) • we have made mock clusters for 40 hours integration at both frequencies

22. Conclusions • SZ scaling relations indicate K0 ≥ 300 keV cm2: inconsistent with isothermal model • no evidence for significant evolution to z~0.7 • SZA and upgraded OVRO array will allow accurate estimates of “entropy floor” to within 50 keV cm2 at z~1