1 / 47

Does AGN “Feedback” in Galaxy Clusters Work?

Does AGN “Feedback” in Galaxy Clusters Work?. Dave De Young NOAO Girdwood AK May 2007. AGN Outflows (“Feedback”). Relevant to Galaxy Formation and Evolution Relevant to Evolution of the Intracluster Medium and BCGs

erma
Download Presentation

Does AGN “Feedback” in Galaxy Clusters Work?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


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

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

  4. Galaxy Formation and Evolution Bower et al. 2003

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

  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. 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. 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, , ) ifAmbient Medium, Interaction Known

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

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

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

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

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

  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 O O s

  15. Current MHD Calculations ( With T. W. Jones, S. O’Niell) • 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

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

  19. Relic Radio Bubble Evolution • Beta = 120

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

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

  22. Three Dimensional MHD Calculations •  = 3000

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

  24. Three Dimensional MHD Calculations •  = 120

  25. Consistency with Observations  = 3000  = 120

  26. Next … • Really Tangled Fields

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

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

  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. 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. 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 7 o turb

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

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

  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. 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? 2 2 Ruszkowski et al. 2004

  36. Non-Linear R-T Instability t = 0 Beta = 1.3 M Beta = 1.3 K 130 ~ ICM 1 kpc slices T = 10M K t = 15 Myr

  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. Relic Radio Bubble Evolution • Bubble Deceleration

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

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

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

  42. Initial Conditions

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

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

  46. Models of Buoyant Radio Source Bubbles • 3-D Hydrodynamic 10 x 10 x 30 kpc 8 Myr 25 Myr 41 Myr 59 Myr Density Brueggen et al. 2002

  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

More Related