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Cosmic Magnetic Fields: Helicity Injection by Supermassive Black Holes, Galaxies and Laboratory Experiments Hui Li 李暉 Los Alamos National Laboratory and.

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Presentation on theme: "Cosmic Magnetic Fields: Helicity Injection by Supermassive Black Holes, Galaxies and Laboratory Experiments Hui Li 李暉 Los Alamos National Laboratory and."— Presentation transcript:

1 Cosmic Magnetic Fields: Helicity Injection by Supermassive Black Holes, Galaxies and Laboratory Experiments Hui Li 李暉 Los Alamos National Laboratory and a member of Center for Magnetic Self-Organization Collaborators: M. Nakamura, S. Li, S. Colgate, J. Finn, K. Fowler  Overview of astrophysical observations of cosmic magnetic fields  Global Electro-Magnetic model for astrophysical jets  Synergy between astrophysics and laboratory plasma physics

2 OpticalX-ray“sound ripples” radio galaxy Fabian et al. Perseus Cluster Perseus A

3 Black Hole Accretion Disk

4

5 Hydra A (Taylor & Perley’93; Colgate & Li’00) 70 kpc Energy and Flux

6 Black hole mass 3.6 million solar Masses (Genzel et al.) Our own backyard Galactic Center

7 Ubiquity of Supermassive Black Holes (Kormendy et al. 2001)

8 Cosmic Energy Flow Gravity Stars, galaxies, galaxy clusters, large scale shocks, etc. IGM “Feedback” Mechanical Chemical Thermal Non-Thermal Magnetic collapse

9 Cosmic Energy Flow Gravity Stars, galaxies, galaxy clusters, large scale shocks, etc. IGM “Feedback” Mechanical Chemical Thermal Non-Thermal Magnetic collapse Black Holes Radiation Kinetic Winds Magnetic fields 10 8 M sun 10 62 ergs

10 High z sources Giants Cluster sources (Kronberg, Dufton, Li, Colgate’02) Magnetic Energy of Radio Lobes

11 Modeling Jets/Lobes 10 14 (solar system) SCALES 10 19 (10pc) 10 22-23 (10 kpc) 10 24 (300 kpc) 10 25 cm (~3 Mpc) Black hole Disk around black hole Host galaxy Radio lobes Mix with IGM?

12 Kinetically Dominated vs. Magnetically Dominated e.g., Norman et al., Clark et al. in 80’s Jones & Ryu et al., Ferrari et al. in 90’s Many, many, others Kinetic Energy Dominated Regime:  v 2 >> B 2

13 Problem Set-up radius R -3/2 

14 Static Limit (v inj << v expan )  Steps: a. Arcade on disk,  (r,z); b. Specify twist profile,  (  ); c. Bounded by pressure, p(  ); d. Find sequences of equilibrium, with increasing toroidal flux, energy, and helicity; Black Hole Accretion Disk (Li et al. 2001)

15 Helix Expansion (Li et al. 2001) Force-free fields expand 60 0 away from the axis; Radial expansion of outer fields are prevented by the plasma pressure.

16 Squeezing Flux Tubes (Parker)

17 Twist Re-distribution --- Collimation Added twists are concentrated around the axis  resulting in collimation.

18 Radius q = rB z /B  BB BzBz BrBr “RFP in the sky?”

19 disk  Viewing it as a magnetic system….. Key Model Ingredients  Poloidal flux:  (r,z)  Electric field and voltage: (-v  B z ) dl = V(r,z)  Injection duration: t inj  Poloidal current: unspecified I z (r,z)  Mag. energy injection rate: dE mag /dt = I z V - P loss  Losses: radiation, pdV, heating, kinetic flows, CRs, etc.  Expansion: I z (r,t),  (r,t), and P loss (r,t). BH Li et al. (2006)

20 Laboratory Plasma Experiments (Bellan et al.)

21 “Gun” Parameter     Gcm 2 )  I ~ 10 19-20 Amperes  r 0 ~ 10 15 cm (disk)  ~ 0.1-10     Gcm 2 )  I ~ 10 5 Amperes  r 0 ~ 10 cm (gun)  ~ 0.1-1 Supermassive Black Hole: Caltech’s Experiment: I pol r

22 Li et al. (2006)  compresses the inner fluxes along the equatorial plane.  “squeezes” the flux vertically out.  expands the outer fluxes outwards.  no azimuthal rotation. Consequences:

23 “Ideal” MHD Simulations S. Li & H. Li (2003, 2006)

24 “Ideal” 3D MHD Simulations  Spherical isothermal background in density and pressure  T=8 keV,  c = 3x10 -3 cm -3, r c =150 kpc; Injection: 3x10 7 yrs, 3x10 59 ergs  320x320x320 simulation (700 kpc) 3  Mass injection: ~ 5 M sun /yr within central 35 kpc

25 log(density) Nakamura, Li & Li (2006) Poloidal J z

26 Hydro-shock Tangential discontinuity Slow-wave

27 “flux core:  & I z ” (“helix/jet”) toroidal B  from I z  (“lobes”) confinement (B 2  /8  ~ p gas) J z @ t = 10

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29 Lobes: Pressure Confinement and Nearly Force-Free

30 Evolution Time Toroidal Flux Poloidal Flux z=0 Poloidal Flux z=6 Poloidal Current I z

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32 log(density) Nakamura, Li & Li (2006) Poloidal J z Stability: with initial perturbations

33 Nakamura, Li & Li (2006)

34

35 Kink Unstable (m=1 mode) Nakamura & Li (2006)

36 J z = 1.5 J z = -0.5Combined

37 KH Stable

38 Perseus A426

39 M87

40 Summary on Jet/Lobe Modeling  Lobes are magnetically dominated and are confined by the surrounding pressure.  Lobes form via background density/pressure changes, accompanied by flux conversion.  Helix is kink-unstable, though the overall structure is not completely destroyed.  Lobes are far from relaxation.

41 Why Plasma Astrophysics?  Common physical processes:  dynamo (magnetic field generation) and flux-conversion dynamo  ideal and resistive MHD stabilities  magnetic reconnection  flow generation  angular momentum transport  particle acceleration  Common numerical tools:  ideal and resistive MHD codes  PIC  gyrokinetic, hybrid, etc.

42 Laboratory Magnetized Plasma Astrophysics

43 You et al. 2005 Hsu & Bellan’03 Laboratory Plasma Experiments for Understanding the Formation and Collimation of Jets Lebedev et al. 2005

44 Individual Galaxy Clusters Super-Galactic Filaments The Magnetized Universe (?)

45 Kronberg et al’03 Farady Rotation Measure

46 Thank you!


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