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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

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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
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


Galaxy formation and evolution
Galaxy Formation and Evolution

  • Millennium Simulation

10

3

1 x 10 Particles; 500Mpc



Galaxy formation and evolution2
Galaxy Formation and Evolution

  • Effects of Radio AGN

Croton et al. 2006


Evolution of the intracluster medium and bcgs
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


Evolution of the intracluster medium and bcgs1
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


Agn outflows
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


Radio source bubbles and cooling flows
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?


Models of buoyant radio source bubbles
Models of Buoyant Radio Source Bubbles

Density

  • 2-D Hydrodynamic

  • Abundant

    Mixing!

X-Y High Resolution

Brueggen & Kaiser 2002


Models of buoyant radio source bubbles1
Models of Buoyant Radio Source Bubbles

  • 3-D Hydrodynamic

    • Fragmentation, Mixing

Ruszkowski, Bruggen, & Begelman 2004


Self Consistent Global Mixing Calculation Not yet Done.

But It’s Suggestive…

However…


Relic sources in clusters
Relic Sources in Clusters

N1275

  • Intact!

    • At Times >> t

instab

Fabian et al. 2002


Consequences of relic radio sources
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


Current mhd calculations
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


  • Initial boundary conditions
    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


  • Initial boundary conditions1
    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


    Relic radio bubble evolution
    Relic Radio Bubble Evolution

    • Beta = 3000

      • Bo = 1 Microgauss

      • Internal B Parallel at Top



    Three dimensional mhd calculations
    Three Dimensional MHD Calculations

    •  = 3000

      • Same Initial

        Conditions as

        2D Cases

        Bubble Material

        Volume Rendered

        t = 12.5 Myr


    Three dimensional mhd calculations1
    Three Dimensional MHD Calculations

    •  = 3000

    t = 75 Myr

    t = 150 Myr



    Three dimensional mhd calculations3
    Three Dimensional MHD Calculations

    •  = 120 bubble only

    t = 150 Myr

    t = 75 Myr



    Consistency with observations
    Consistency with Observations

     = 3000

     = 120


    Next …

    • Really

      Tangled

      Fields




    Conclusions agn outflows and reheating of the ambient medium
    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


    Conclusions agn outflows and reheating of the ambient medium1
    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


    Consequences of b fields
    Consequences of B Fields Medium

    • 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


    Other possible heating processes due to radio sources
    Other Possible Heating Processes Due to Radio Sources Medium

    • Sound Waves?

    • Shock Waves?

    P/P

    Fabian et al. 2005


    Impact of radio source cavities
    Impact of Radio Source Cavities Medium

    • Complex ICM Structure – Centaurus Cluster

      Fabian et al. 2005

    0.4 – 7 keV + 1.4 GHz


    Other possible heating processes shock waves
    Other Possible Heating Processes – Shock Waves Medium

    • 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


    Other possible heating processes dissipation of sound waves
    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


    Non linear r t instability
    Non-Linear R-T Instability Waves

    t = 0

    Beta = 1.3 M

    Beta = 1.3 K

    130 ~ ICM

    1 kpc slices T = 10M K t = 15 Myr


    Prior mhd calculations
    Prior MHD Calculations Waves

    • 2-D MHD – Pre-formed Bubble

      • Tangential Field Inserted “By Hand”

      • Self Consistent MHD (Robinson et al. 2004)

    Breuggen & Kaiser 2001


    Relic radio bubble evolution2
    Relic Radio Bubble Evolution Waves

    • Bubble

      Deceleration


    Lifting and mixing
    Lifting and Mixing Waves

    Beta = 120K OptimallyCoupled

    Ambient ICM


    Relic radio bubble evolution3
    Relic Radio Bubble Evolution Waves

    • Beta = 3000

      • Bo = 1 Microgauss; Internal B Antiparallel at Top

    12.5 Myr

    75

    125


    Relic sources in clusters1
    Relic Sources in Clusters Waves

    • 200 kpc Cavities (McNamara et al. 2005)

      • MS0735

      • Z = 0.22

      • pdV ~ 10 erg

    62



    Properties of radio source cavities and shells
    Properties of Radio Source Cavities and Shells Waves

    • 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


    Relic radio bubble evolution4
    Relic Radio Bubble Evolution Waves

    • Beta = 3000

      • Bo = 1 Microgauss

      • Internal B

        Anti-parallel at Top


    Three dimensional mhd calculations5
    Three Dimensional MHD Calculations Waves

    •  = 75000

    Bubble Only - Volume Rendered


    Models of buoyant radio source bubbles2
    Models of Buoyant Radio Source Bubbles Waves

    • 3-D Hydrodynamic

    10 x 10 x 30 kpc

    8 Myr

    25 Myr

    41 Myr

    59 Myr

    Density

    Brueggen et al. 2002


    Evolution of the intracluster medium and bcgs2
    Evolution of The Intracluster Medium and BCGs Waves

    • Related to Previous Problem in ΛCDM Cosmology Models

    • Large ΛCDM Halos Form Late, Correspond to Massive Clusters

    Z = 0, M/L = Const


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