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Does AGN “Feedback” in Does AGN “Feedback” in Galaxy Clusters Work?Galaxy Clusters Work?

Dave De Young

NOAO

Girdwood AK May 2007

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AGN Outflows (“Feedback”)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

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Galaxy Formation and Galaxy Formation and EvolutionEvolution

Millennium Simulation

1 x 10 Particles; 500 Mpc10 3

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Galaxy Formation and Galaxy Formation and EvolutionEvolution

Bower et al. 2003

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Galaxy Formation and Galaxy Formation and EvolutionEvolution

– Effects of Radio AGN

Croton et al. 2006

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Evolution of The Intracluster Evolution of The Intracluster Medium and BCGsMedium 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

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Evolution of The Intracluster Evolution of The Intracluster Medium and BCGsMedium and BCGs

ICM Cooling Times < Hubble Time in Cores– Inflow Rates Up 100 M(solar) /yr– Not Seen– “Cooling Flow” Problem

Reheating by Cluster AGNOld Idea (~ 1970s) : Total Energies Suggestive

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AGN OutflowsAGN 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

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Radio Source Bubbles and Radio Source Bubbles and Cooling “Flows”Cooling “Flows”

Total Radio Source Energies (pdV) Are a Significant Fraction of ICM Energy Budget– Need to Convert Kinetic and Particle Energy

into HeatVia Turbulent Mixing with ICMVia Advection and Mixing of ICMVia Shocks in ICM

– Is There Enough Time to Do This?

(cf. B. McNamara)

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Models of Buoyant Radio Models of Buoyant Radio Source BubblesSource Bubbles

2-D Hydrodynamic

Abundant

Mixing!

X-Y High Resolution

Brueggen & Kaiser 2002

Density

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Models of Buoyant Radio Models of Buoyant Radio Source BubblesSource Bubbles

3-D Hydrodynamic

– Fragmentation, Mixing

Ruszkowski, Bruggen, & Begelman 2004

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Self Consistent Global Mixing Calculation Not yet Done.

But It’s Suggestive…

However…

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Relic Sources in ClustersRelic Sources in Clusters

N1275

Intact!– At Times >> t

Fabian et al. 2002

instab

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Consequences of Relic Radio Consequences of Relic Radio SourcesSources

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

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Current MHD CalculationsCurrent MHD Calculations

Time Dependent Evolution of Buoyant Radio Relics in a Stratified ICM – Look At:

R – T InstabilityLifting and Mixing of Different Elements of the ICMDestruction 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)

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Initial & Boundary ConditionsInitial & 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

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Initial & Boundary ConditionsInitial & Boundary Conditions

ICM – Equilibrium Configuration– Magnetic Field

Orientation: Phi = 0, 45, 90B = const or Beta = const (120 – 75K) |B| = 0.2, 1, 5 MicroGauss (Beta = 7.5(4), 3(3), 120)

Bubble R = 2 kpcP = Pext at z = 15 kpcn = 0.01n at z = 15 kpc Inflation time ~ 10 MyrdE/dt ~ 10 (42) erg/s

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Relic Radio Bubble EvolutionRelic Radio Bubble Evolution

Beta = 3000Bo = 1 Microgauss Internal B Parallel at Top

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Relic Radio Bubble EvolutionRelic Radio Bubble Evolution

Beta = 120

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Three Dimensional MHD Three Dimensional MHD CalculationsCalculations

= 3000– Same Initial

Conditions as

2D Cases

Bubble MaterialVolume Rendered

t = 12.5 Myr

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Three Dimensional MHD Three Dimensional MHD CalculationsCalculations

= 3000

t = 75 Myrt = 150 Myr

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Three Dimensional MHD Three Dimensional MHD CalculationsCalculations

= 3000

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Three Dimensional MHD Three Dimensional MHD CalculationsCalculations

= 120 bubble only

t = 75 Myr

t = 150 Myr

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Three Dimensional MHD Three Dimensional MHD CalculationsCalculations

= 120

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Consistency with Consistency with ObservationsObservations

= 120

= 3000

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Next …Next …

Really

Tangled

Fields

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Bubbles with Tangled Interior Bubbles with Tangled Interior FieldsFields

– Beta = 120– t = 75 Myr

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Bubbles with Tangled Interior Bubbles with Tangled Interior FieldsFields

– Beta = 120– t = 75 Myr

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Conclusions – AGN Outflows and Conclusions – AGN Outflows and Reheating of the Ambient MediumReheating 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

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Conclusions – AGN Outflows and Conclusions – AGN Outflows and Reheating of the Ambient MediumReheating 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

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Consequences of B FieldsConsequences 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

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Other Possible Heating Processes Other Possible Heating Processes Due to Radio Sources Due to Radio Sources

Sound Waves? Shock Waves?

Fabian et al. 2005

P/P

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Impact of Radio Source Impact of Radio Source CavitiesCavities

Complex ICM Structure – Centaurus Cluster

Fabian et al. 2005

0.4 – 7 keV + 1.4 GHz

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Other Possible Heating Processes Other Possible Heating Processes – Shock Waves– Shock Waves

Shock Waves:– Must be Supersonic

Sound Speed ~ 10 T Bubble Expansion Speed > 10 cm/s

– Likely to be Weak and Short LivedT* /T M, so T Not LargeBubbles Currently SubsonicVolume Heated Will be SmallDamped Shocks Become Sound Waves

– Thus a Local Phenomenon

4

8

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Other Possible Heating Processes Other Possible Heating Processes – Dissipation of Sound Waves– 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

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Non-Linear R-T InstabilityNon-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

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Prior MHD CalculationsPrior MHD Calculations

2-D MHD – Pre-formed BubbleTangential Field Inserted “By Hand”

Self Consistent MHD (Robinson et al. 2004)

Breuggen & Kaiser 2001

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Relic Radio Bubble EvolutionRelic Radio Bubble Evolution

Bubble

Deceleration

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Lifting and MixingLifting and MixingBeta = 120K OptimallyCoupled

Ambient ICM

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Relic Radio Bubble EvolutionRelic Radio Bubble Evolution

Beta = 3000Bo = 1 Microgauss; Internal B Antiparallel at Top

12.5 Myr

75

125

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Relic Sources in ClustersRelic Sources in Clusters 200 kpc Cavities (McNamara et al. 2005)

– MS0735– Z = 0.22– pdV ~ 10 erg

62

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Initial ConditionsInitial Conditions

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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– Moving Subsonically (no Shocks)– Shell and Surroundings Cool– Buoyant Bubbles

7syn

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Relic Radio Bubble EvolutionRelic Radio Bubble Evolution

Beta = 3000Bo = 1 Microgauss Internal B

Anti-parallel at Top

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Three Dimensional MHD Three Dimensional MHD CalculationsCalculations

= 75000

Bubble Only - Volume Rendered

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Models of Buoyant Radio Models of Buoyant Radio Source BubblesSource Bubbles

3-D Hydrodynamic

Density8 Myr 25 Myr 41 Myr 59 Myr

Brueggen et al. 2002

10 x 10 x 30 kpc

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Evolution of The Intracluster Evolution of The Intracluster Medium and BCGsMedium and BCGs

Related to Previous Problem in ΛCDM Cosmology Models

Large ΛCDM Halos Form Late, Correspond to Massive Clusters

Z = 0, M/L = Const