Radio Galaxies in X-Ray Light: Radio Galaxies in X-Ray Light: Problems and ProcessesProblems and Processes

Dave De YoungNOAO

Radio Galaxies in the Chandra Era

8-11 July 2008

Major Unresolved Issues – Radio Major Unresolved Issues – Radio Galaxies in the Pre-Chandra eraGalaxies 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

Major “Resolved” Issues – Radio Major “Resolved” Issues – Radio Galaxies in the Pre-Chandra eraGalaxies 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

Some Major Revelations from Some Major Revelations from ChandraChandra

• Extended X-Ray Emission From Jets, Hot Spots, and Lobes

Revelations from Chandra – Revelations from Chandra – Large Scale X-Ray JetsLarge 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

Revelations from Chandra – Low Revelations from Chandra – Low Power (FR I) X-Ray JetsPower (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?

Revelations from Chandra – Hot Revelations from Chandra – Hot Spots and LobesSpots 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

Revelations from Chandra – Large Revelations from Chandra – Large Scale (QSO, FR II, Blazar) X-Ray JetsScale (QSO, FR II, Blazar) X-Ray Jets

Schwartz et al. 2000Sambruna et al. 2004

Large Scale X-Ray JetsLarge Scale X-Ray Jets

Harris & Krawczynski 2006

Siemiginowska et al. 2007, 2008

Large Scale X-Ray JetsLarge 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

Large Scale X-Ray JetsLarge Scale X-Ray Jets

• Electron

Kataoka & Stawartz 2005

Large Scale X-Ray Jets – The Large Scale X-Ray Jets – The IC/CMB ModelIC/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

IC/CMB IssuesIC/CMB Issues

Kataoka et al. 2008

3C 33 Kraft et al. 2007

Revelations from Chandra – Revelations from Chandra – Large Scale X-Ray JetsLarge 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)

Other Radio Galaxy Results Other Radio Galaxy Results from Chandrafrom Chandra

• Radio Galaxy Interactions with the Environment

• E.g., Cen A (Kraft et al. 2007)

More Major Revelations from More Major Revelations from ChandraChandra

• Radio Galaxy Inflated Cavities in Clusters

NGC 1285/Perseus

Fabian et al. 2000

Radio Source CavitiesRadio Source Cavities

• N1275

Fabian et al. 2000

Radio Source Cavities in Radio Source Cavities in ClustersClusters

• Chandra A2052 + 6cm VLA (3C 317)

Blanton et al. 2001, Burns 1990

Properties of Radio Source Properties of Radio Source Cavities and ShellsCavities 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

7syn

Relic Sources in ClustersRelic Sources in Clusters

• N1275

74 MHz

Fabian et al. 2002

Properties of Radio RelicsProperties 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)

int equip

59

instab

8

Calorimetry of Radio Galaxy Calorimetry of Radio Galaxy OutflowsOutflows

• After > 35 Years of Assumptions and Guessing

McNamara & Nulsen 2007

Calorimetry of Radio Sources in Calorimetry of Radio Sources in ClustersClusters

• MS 0735– Z = 0.22

• pdV ~ 10 erg!62

McNamara et al. 2005, 2007

Stability of Relic Sources in Stability of Relic Sources in Clusters Clusters

• t >> tbuoy R-T, K-H

vs

The “Cooling Flow” Problem and The “Cooling Flow” Problem and Heating Due to Radio SourcesHeating Due to Radio Sources

• Sound Waves?

• Shock Waves?

Fabian et al. 2005

P/P

What Have We Learned and What Have We Learned and What Remains Unsolved?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

A Possible Path to Further A Possible Path to Further Progress – Jet Interactions With Progress – Jet Interactions With

Their EnvironmentTheir 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

AGN OutflowsAGN Outflows

• FRII

3C983C223 – 20cm

AGN OutflowsAGN Outflows

• FRI

AGN OutflowsAGN Outflows

• FRI

AGN OutflowsAGN Outflows

AGN OutflowsAGN Outflows– Surface Brightness

Outflow Interaction with Outflow Interaction with Ambient MediumAmbient Medium

• Fully Non-Linear K-H Instability:– Development of Turbulent Mixing Layer

Mixing LayersMixing Layers

• Thickness Grows with Distance/Time

• Mixing Layer Can Permeate Entire Jet

-RELHL )(v)/( CTan

Mixing LayersMixing Layers• Entrainment Very Effective

– “Ingest – Digest” Process

Mixing LayersMixing Layers• K-H and Mixing Layers in Supersonic Flows

• Relativistic Flows– 3D Simulations

• Rigidity

• Deceleration

• Development of

Shear/Mixing LayersAloy et al.; Marti et al. 1999-2003

The Effect of Magnetic FieldsThe 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

Mixing LayersMixing Layers• MHD Plus Relativistic

Mizuno et al. 2007

Outflow Interaction Via Outflow Interaction Via Surface InstabilitiesSurface 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

Consequences of Mixing LayersConsequences of Mixing Layers

• Saturated Mixed Jets - and FR I Source Morphology

Consequences of Mixing LayersConsequences of Mixing Layers

• Entrainment

• Deceleration

• Spine/Sheath Structure

• Decollimation

• How Much of Each?– TanΘ ~ (ρ /ρ ) / M 3C223 – 20cm

1 2

Consequences of Mixing Layers: Consequences of Mixing Layers: IC/CMB ModelsIC/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

Consequences of Mixing Layers: Consequences of Mixing Layers: IC/CMB Models – Other IssuesIC/CMB Models – Other Issues

• Evidence for Sustained Energy Transport

• Where are “Debeamed” Jets?

• Probable Need for Jet Models

With Complex Internal Velocity

StructureHardcastle 2006

Another Possibility 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

Evolution of Turbulent FlowsEvolution of Turbulent Flows

• Development of the Turbulent Cascade

Issues for This WeekIssues 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

Issues for This WeekIssues 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