Radio Galaxies in X-Ray Light: Processes and Challenges

1. Radio Galaxies in X-Ray Light: Problems and Processes Dave De Young NOAO Radio Galaxies in the Chandra Era 8-11 July 2008

2. Major Unresolved Issues – Radio Galaxies in the Pre-Chandra era • Origins of Energetic Particles – How and Where • Formation of Bipolar Outflows • Collimation Mechanisms • Outflow Speeds • Outflow Content • Total Energies • Outflow Lifetimes

3. Major “Resolved” Issues – Radio Galaxies in the Pre-Chandra era • Morphology/Radio Luminosity Classification – FR-I and FR-II • Radio Radiation - Incoherent Synchrotron • Must Have Relativistic Electrons and Magnetic Fields • “Superluminal Features” on Small Scales

4. Some Major Revelations from Chandra • Extended X-Ray Emission From Jets, Hot Spots, and Lobes

5. Revelations from Chandra – Large Scale X-Ray Jets • Electron Synchrotron Lifetimes in Equipartition Fields: • X-Ray: Decades to Centuries • Optical and UV: Millennia • Therefore High Energy Electrons Cannot Have Been Energized Only in Nucleus • Immediate Impact on Models

6. Revelations from Chandra – Low Power (FR I) X-Ray Jets • Electron Synchrotron Models Can Work • Single SED Can Fit Radio to X-Ray • Requires Local Acceleration in Knots • Can Produce Offsets • Simultaneous Variations at X-ray to Radio • Problems/Uncertainties: • Distributed Acceleration – Two Populations? • Occasional Wrong SED • No Radiative Cooling Signatures?

7. Revelations from Chandra – Hot Spots and Lobes • X-Ray Emission Consistent with SSC and IC/CMB Under Equipartition Conditions • First “Verification” of Equipartition Assumption • Kataoka & Stawartz 2005, Croston et al. 2005

8. Revelations from Chandra – Large Scale (QSO, FR II, Blazar) X-Ray Jets Schwartz et al. 2000 Sambruna et al. 2004

9. Large Scale X-Ray Jets Harris & Krawczynski 2006 Siemiginowska et al. 2007, 2008

10. Large Scale X-Ray Jets • The IC/CMB Model • Tavecchio et al. 2000, Celotti et al. 2001 • PKS 0637-752: Γ ~ 10 • Reproduces SED • Has Three Basic Assumptions • Equipartition Conditions • Relativistic Motion on 10-100 Kpc Scales • Population of Low Energy electrons Schwartz et al. 2000

11. Large Scale X-Ray Jets • Electron Kataoka & Stawartz 2005

12. Large Scale X-Ray Jets – The IC/CMB Model • Some Issues • Low Energy γ ~ 10-100: Long Electron Lifetimes • Why X-Ray Knots? • Required Beaming Angles Imply Jet Lengths ~ 1 Mpc or More, >> FR II Jets • Equipartition + Low Energy End of Spectrum May Imply “Too Much” Energy • Bulk Speeds at 100s kpc >> Other Derived Values

13. IC/CMB Issues Kataoka et al. 2008 3C 33 Kraft et al. 2007

14. Revelations from Chandra – Large Scale X-Ray Jets • Reacceleration for Electron Synchrotron • First Insights into Energy Injection Question • Stringent Requirements on Shock Models • Can Account for Most Low Power FR-I Jets • Possibility of IC/CMB for FR-II/Quasar Jets • Requires Relativistic Bulk Motion at 100s kpc • First Possible Clues to Jet Speeds on Large Scales • Implies Low Energy Electron Population • First Possible Constraints on γ(min)

15. Other Radio Galaxy Results from Chandra • Radio Galaxy Interactions with the Environment • E.g., Cen A (Kraft et al. 2007)

16. More Major Revelations from Chandra • Radio Galaxy Inflated Cavities in Clusters NGC 1285/Perseus Fabian et al. 2000

17. Radio Source Cavities • N1275 Fabian et al. 2000

18. Radio Source Cavities in Clusters • Chandra A2052 + 6cm VLA (3C 317) Blanton et al. 2001, Burns 1990

19. 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 • Generally Moving Subsonically • Shell and Surroundings Cool • Buoyant Bubbles 7 syn

20. Relic Sources in Clusters • N1275 74 MHz Fabian et al. 2002

21. Properties of Radio Relics • They Are Intact! At Times >> t • Reside 30-50 kpc From Cluster Center • Diameter 10-20 kpc • Buoyant Risetimes ~ 10 yr > Synchrotron Lifetime • Equilibrium Implies U >> U • PdV Work ~ 10 erg (or More) instab 8 int equip 59

22. Calorimetry of Radio Galaxy Outflows • After > 35 Years of Assumptions and Guessing McNamara & Nulsen 2007

23. Calorimetry of Radio Sources in Clusters • MS 0735 • Z = 0.22 • pdV ~ 10 erg! 62 McNamara et al. 2005, 2007

24. Stability of Relic Sources in Clusters • t >> t buoy R-T, K-H vs

25. The “Cooling Flow” Problem and Heating Due to Radio Sources • Sound Waves? • Shock Waves? P/P Fabian et al. 2005

26. What Have We Learned and What Remains Unsolved? • Origins of Energetic Particles – In Situ Acceleration Required in Addition to Nuclear Processes • Formation of Bipolar Outflows – ? See Finis • Collimation Mechanisms – ? See Finis • Outflow Speeds – May Be Relativistic on Mpc Scales • Outflow Content – Coupled to Speed Question? • Total Energies – Enormous Progress: Firm Limits • Outflow Lifetimes – See Item 4

27. A Possible Path to Further Progress – Jet Interactions With Their Environment • Key Issue: The Coupling of AGN Outflow to the Surrounding Medium • Ambient Medium with Known Properties • Determination of Dominant Physical Processes at Work • Constrain Basic Parameters of Outflow

28. AGN Outflows • FRII 3C223 – 20cm 3C98

29. AGN Outflows • FRI

30. AGN Outflows • FRI

31. AGN Outflows

32. AGN Outflows • Surface Brightness

33. Outflow Interaction with Ambient Medium • Fully Non-Linear K-H Instability: • Development of Turbulent Mixing Layer

34. a b f = r r - Tan C ( / ) (v ) L H REL Mixing Layers • Thickness Grows with Distance/Time • Mixing Layer Can Permeate Entire Jet

35. Mixing Layers • Entrainment Very Effective • “Ingest – Digest” Process

36. Mixing Layers • K-H and Mixing Layers in Supersonic Flows • Relativistic Flows • 3D Simulations • Rigidity • Deceleration • Development of Shear/Mixing Layers Aloy et al.; Marti et al. 1999-2003

37. The Effect of Magnetic Fields • Can Stabilize – In Principle • Three Dimensional MHD • For High Beta > 100 • Evolves to Turbulence • Turbulent B Amplification • Enhanced Dissipation due to Magnetic Reconnection • Instability Remains “Essentially Hydrodynamic” Ryu et al. 2000

38. Mixing Layers • MHD Plus Relativistic Mizuno et al. 2007

39. Outflow Interaction Via Surface Instabilities • Virtually Universal (One Possible Exception) • Present at Some Level in Outflows in All Environments • Global • Involve Most of Jet Surface for Long Times • Inevitable (?) • Very Special Circumstances Required to Prevent Occurrence

40. Consequences of Mixing Layers • Saturated Mixed Jets - and FR I Source Morphology

41. Consequences of Mixing Layers • Entrainment • Deceleration • Spine/Sheath Structure • Decollimation • How Much of Each? • TanΘ ~ (ρ /ρ ) / M a 3C223 – 20cm 1 2

42. Consequences of Mixing Layers: IC/CMB Models • Can Γ ~ 10 to ~ Mpc be Sustained? • Other Measures of Γ: v Structure • Is U >> U ? • Implications for Content • What is “Too Much” Energy? p B

43. Consequences of Mixing Layers: IC/CMB Models – Other Issues • Evidence for Sustained Energy Transport • Where are “Debeamed” Jets? • Probable Need for Jet Models With Complex Internal Velocity Structure Hardcastle 2006

44. Another Possibility • Poynting Flux Jets • Origins Well Defined • Initial Collimation Solved • Development of Mixing Layer – Not Clear • Long Term Collimation? • Particle Content? Li et al. 2006

45. Evolution of Turbulent Flows • Development of the Turbulent Cascade

46. Issues for This Week • The FRI / FRII Dichotomy (and IC/CMB Jets) • Difference in Degree or Kind? • Nature vs. Nurture • Jet Content • Jet Speed • Collimation • Difficult with External Pressure ( ~ d ) • Difficult with Magnetic Fields a

47. Issues for This Week • Poynting Flux Jets • Are There Unique Observational Signatures? • Radio Sources in Clusters • Cooling Flows, Feedback etc. • Consequences for General Radio Sources • Total Energies • Energy Fluxes • Outflow Speeds • Jet Content