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

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

Black Hole Accretion Disk

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

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

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

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

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 ergs

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

Modeling Jets/Lobes (solar system) SCALES (10pc) (10 kpc) (300 kpc) cm (~3 Mpc) Black hole Disk around black hole Host galaxy Radio lobes Mix with IGM?

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

Problem Set-up radius R -3/2 

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)

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.

Squeezing Flux Tubes (Parker)

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

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

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)

Laboratory Plasma Experiments (Bellan et al.)

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

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:

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

“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

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

Hydro-shock Tangential discontinuity Slow-wave

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

Lobes: Pressure Confinement and Nearly Force-Free

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

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

Nakamura, Li & Li (2006)

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

J z = 1.5 J z = -0.5Combined

KH Stable

Perseus A426

M87

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.

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.

Laboratory Magnetized Plasma Astrophysics

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

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

Kronberg et al’03 Farady Rotation Measure

Thank you!