1. 1 Does AGN “Feedback” in Galaxy Clusters Work? Dave De Young NOAO Girdwood AK May 2007

2. 2 AGN Outflows (“Feedback”) Relevant to Galaxy Formation and Evolution Relevant to Evolution of the Intracluster Medium and BCGs Can Provide Information on Unknown Parameters of AGN Formation and Evolution

3. 3 Galaxy Formation and Evolution Millennium Simulation 1 x 10 Particles; 500 Mpc 10 3

4. 4 Galaxy Formation and Evolution Bower et al. 2003

5. 5 Galaxy Formation and Evolution – Effects of Radio AGN Croton et al. 2006

6. 6 Evolution of The Intracluster Medium and BCGs Central Cluster Galaxies Should Now be Accreting ICM, Forming Stars (  CDM) Not Seen – Massive Elliptical Galaxies in Clusters are Old and Red – No Evidence of Significant Star Formation in Central BCGs

7. 7 Evolution of The Intracluster Medium and BCGs ICM Cooling Times < Hubble Time in Cores – Inflow Rates Up 100 M(solar) /yr – Not Seen – “Cooling Flow” Problem Reheating by Cluster AGN Old Idea (~ 1970s) : Total Energies Suggestive

8. 8 AGN Outflows Key Issue: Coupling of AGN Outflow to Surrounding Medium – Requires Understanding of the Interaction of AGN Outflows with the Ambient Medium – Exchange of E, M, p – May Constrain Outflow Parameters (v, ,  ) if Ambient Medium, Interaction Known

9. 9 Radio Source Bubbles and Cooling “Flows” Total Radio Source Energies (pdV) Are a Significant Fraction of ICM Energy Budget – Need to Convert Kinetic and Particle Energy into Heat Via Turbulent Mixing with ICM Via Advection and Mixing of ICM Via Shocks in ICM – Is There Enough Time to Do This? (cf. B. McNamara)

10. 10 Models of Buoyant Radio Source Bubbles 2-D Hydrodynamic Abundant Mixing! X-Y High Resolution Brueggen & Kaiser 2002 Density

11. 11 Models of Buoyant Radio Source Bubbles 3-D Hydrodynamic – Fragmentation, Mixing Ruszkowski, Bruggen, & Begelman 2004

12. 12 Self Consistent Global Mixing Calculation Not yet Done. But It’s Suggestive … However…

13. 13 Relic Sources in Clusters N1275 Intact! – At Times >> t Fabian et al. 2002 instab

14. 14 Consequences of Relic Radio Sources Role of Magnetic Fields: – Does Bubble Expansion Creates Stabilizing Sheath? Linear Stability Analysis: – At r ~ 50 kpc, n = 0.01, B = 3 x 10 G: – R-T: l = 13 kpc, t = 7 x 10 yr – K-H: Stable for U ~ 0.1 c Possible Suppression of Fragmentation or Mixing for a Significant Fraction of Buoyant Risetime -6 7 s O O

15. 15 Current MHD Calculations Time Dependent Evolution of Buoyant Radio Relics in a Stratified ICM – Look At: R – T Instability Lifting and Mixing of Different Elements of the ICM Destruction of Relic and Mixing with ICM Includes Effects of Central Galaxy + Cluster Includes Inflation of Radio Relic Bubble ( With T. W. Jones, S. O’Niell)

16. 16 Initial & Boundary Conditions Gravitation – Includes Dark Matter – Central Galaxy – King Model; Mc = 3 kpc; M = 3.5 x 10(12) Mo at 20 kpc – Cluster – NFW Model; alpha = 0; M = 3.5 x 10(10) Mo at 10 kpc – Cluster Core = 400 kpc; M = 3.5 x 10(12) Mo at 50 kpc ICM – Equilibrium Configuration – Isothermal – T = 3 keV = 3.5 x10(7) K – Density n = 0.1 at z = 5 kpc

17. 17 Initial & Boundary Conditions ICM – Equilibrium Configuration – Magnetic Field Orientation: Phi = 0, 45, 90 B = const or Beta = const (120 – 75K) |B| = 0.2, 1, 5 MicroGauss (Beta = 7.5(4), 3(3), 120) Bubble R = 2 kpc P = Pext at z = 15 kpc n = 0.01n at z = 15 kpc Inflation time ~ 10 Myr dE/dt ~ 10 (42) erg/s

18. 18 Relic Radio Bubble Evolution Beta = 3000 Bo = 1 Microgauss Internal B Parallel at Top

19. 19 Relic Radio Bubble Evolution Beta = 120

20. 20 Three Dimensional MHD Calculations  = 3000 – Same Initial Conditions as 2D Cases Bubble Material Volume Rendered t = 12.5 Myr

21. 21 Three Dimensional MHD Calculations  = 3000 t = 75 Myr t = 150 Myr

22. 22 Three Dimensional MHD Calculations  = 3000

23. 23 Three Dimensional MHD Calculations  = 120 bubble only t = 75 Myr t = 150 Myr

24. 24 Three Dimensional MHD Calculations  = 120

25. 25 Consistency with Observations Consistency with Observations  = 120  = 3000

26. 26 Next … Next … Really Tangled Fields

27. 27 Bubbles with Tangled Interior Fields – Beta = 120 – t = 75 Myr

28. 28 Bubbles with Tangled Interior Fields – Beta = 120 – t = 75 Myr

29. 29 Conclusions – AGN Outflows and Reheating of the Ambient Medium Radio Lobe Interaction with a Magnetized ICM Indicates: – Delay of Onset of Destructive Instabilities – Longer Times for Mixing with the ICM – Bubbles Decelerated, Evolution Subsonic – Volume of Lifted ICM Limited to Wake Region Repeated Outbursts and/or Additional Mixing Mechanisms May be Needed to Reheat the ICM

30. 30 Conclusions – AGN Outflows and Reheating of the Ambient Medium AGN Reheating Needed in  CDM Galaxy Formation Common FR-I Outflows May Show Strong Local Coupling – Self Consistent Heating Rates not Yet Calculated AGN Outflows in Clusters – Stop Cooling Flows? – Hydro Calculations Suggestive – Relic Radio Source Cavities Intact and Suggest Interaction with a Magnetized ICM

31. 31 Consequences of B Fields For Cluster ICM Reheating – Onset of Instability and Mixing Delayed – Initial Scale Length Large: l ~ 10 kpc Mixing Time to Reheat Will Be Long - Time Required for Turbulent Cascade to Go From Energy Range to Dissipation Range – l /v ~ 3 x 10 yr o o turb 7

32. 32 Other Possible Heating Processes Due to Radio Sources Sound Waves? Shock Waves? Fabian et al. 2005  P/P

33. 33 Impact of Radio Source Cavities Complex ICM Structure – Centaurus Cluster Fabian et al. 2005 0.4 – 7 keV + 1.4 GHz

34. 34 Other Possible Heating Processes – Shock Waves Shock Waves: – Must be Supersonic Sound Speed ~ 10  T  Bubble Expansion Speed > 10 cm/s – Likely to be Weak and Short Lived T* /T  M, so  T Not Large Bubbles Currently Subsonic Volume Heated Will be Small Damped Shocks Become Sound Waves – Thus a Local Phenomenon 4 8

35. 35 Other Possible Heating Processes – Dissipation of Sound Waves Dissipation of Sound Waves – Some Models Assume pdV Energy Dissipated in Cluster Core – Others – Approximate Dissipation (no B, no Thermal Conductivity, Incompressible) L  (3/8  ) c / ~ 100 kpc Issue Not Yet Clear – How Much? – How Long? 22 Ruszkowski et al. 2004

36. 36 Non-Linear R-T Instability t = 0 Beta = 1.3 MBeta = 1.3 K130 ~ ICM 1 kpc slices T = 10M K t = 15 Myr

37. 37 Prior MHD Calculations 2-D MHD – Pre-formed Bubble Tangential Field Inserted “By Hand” Self Consistent MHD (Robinson et al. 2004) Breuggen & Kaiser 2001

38. 38 Relic Radio Bubble Evolution Bubble Deceleration

39. 39 Lifting and Mixing Beta = 120K OptimallyCoupled Ambient ICM

40. 40 Relic Radio Bubble Evolution Beta = 3000 Bo = 1 Microgauss; Internal B Antiparallel at Top 12.5 Myr 75 125

41. 41 Relic Sources in Clusters 200 kpc Cavities (McNamara et al. 2005) – MS0735 – Z = 0.22 – pdV ~ 10 erg 62

42. 42 Initial Conditions

43. 43 Properties of Radio Source Cavities and Shells Morphology – Limb Brightened, “Relaxed” Structure – NOT Head-Tail or “Normal” FR-I – Small/No Jets, but t ~ 10 yr – Tens of kpc in Diameter Inferred Properties – In Pressure Equilibrium – Moving Subsonically (no Shocks) – Shell and Surroundings Cool – Buoyant Bubbles 7 syn

44. 44 Relic Radio Bubble Evolution Beta = 3000 Bo = 1 Microgauss Internal B Anti-parallel at Top

45. 45 Three Dimensional MHD Calculations  = 75000 Bubble Only - Volume Rendered

46. 46 Models of Buoyant Radio Source Bubbles 3-D Hydrodynamic Density 8 Myr25 Myr41 Myr59 Myr Brueggen et al. 2002 10 x 10 x 30 kpc

47. 47 Evolution of The Intracluster Medium and BCGs Related to Previous Problem in ΛCDM Cosmology Models Large ΛCDM Halos Form Late, Correspond to Massive Clusters Z = 0, M/L = Const