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Hui Li 李暉 Los Alamos National Laboratory and a member of Center for Magnetic Self-Organization PowerPoint Presentation
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Hui Li 李暉 Los Alamos National Laboratory and a member of Center for Magnetic Self-Organization

Hui Li 李暉 Los Alamos National Laboratory and a member of Center for Magnetic Self-Organization

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Hui Li 李暉 Los Alamos National Laboratory and a member of Center for Magnetic Self-Organization

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  1. Cosmic Magnetic Fields: Helicity Injection bySupermassive 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. Perseus Cluster radio galaxy Optical X-ray “sound ripples” Perseus A Fabian et al.

  3. Black Hole Accretion Disk

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

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

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

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

  8. Cosmic Energy Flow Gravity IGM collapse “Feedback” Mechanical Chemical Thermal Non-Thermal Magnetic Radiation Kinetic Winds Magnetic fields Stars, galaxies, galaxy clusters, large scale shocks, etc. Black Holes 108 Msun 1062 ergs

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

  10. Modeling Jets/Lobes Host galaxy Disk around black hole Mix with IGM? Black hole Radio lobes SCALES 1019 (10pc) 1022-23 (10 kpc) 1024 (300 kpc) • 1025 cm • (~3 Mpc) 1014 (solar system)

  11. 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:  v2 >> B2

  12. Problem Set-up W R-3/2 radius

  13. Static Limit(vinj << vexpan) • Steps: a. Arcade on disk, Y(r,z); b. Specify twist profile, F(y); c. Bounded by pressure, p(y); d. Find sequences of equilibrium, with increasing toroidal flux, energy, and helicity; Accretion Disk Black Hole (Li et al. 2001)

  14. Helix Expansion (Li et al. 2001) • Force-free fields expand 600 away from the axis; • Radial expansion of outer fields are prevented by the plasma pressure.

  15. Squeezing Flux Tubes(Parker)

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

  17. “RFP in the sky?” Br Bz Bf q = rBz/Bf Radius

  18. Viewing it as a magnetic system….. Key Model Ingredients  • Poloidal flux: (r,z) • Electric field and voltage: (-vBz) dl = V(r,z) • Injection duration: tinj • Poloidal current: unspecifiedIz(r,z) • Mag. energy injection rate: dEmag/dt = Iz V - Ploss • Losses: radiation, pdV, heating, kinetic flows, CRs, etc. • Expansion: Iz(r,t), (r,t), and Ploss(r,t). BH disk Li et al. (2006)

  19. Laboratory Plasma Experiments (Bellan et al.)

  20. Ipol r Caltech’s Experiment: Supermassive Black Hole: • Gcm2) • I ~ 1019-20 Amperes • r0 ~ 1015 cm (disk)  ~ 0.1-10 • Gcm2) • I ~ 105 Amperes • r0 ~ 10 cm (gun)  ~ 0.1-1 “Gun” Parameter

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

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

  23. “Ideal” 3D MHD Simulations • Spherical isothermal background in density and pressure • T=8 keV, c = 3x10-3 cm-3, rc=150 kpc; Injection: 3x107 yrs, 3x1059 ergs • 320x320x320 simulation (700 kpc)3 • Mass injection: ~ 5 Msun/yr within central 35 kpc

  24. log(density) Poloidal Jz Nakamura, Li & Li (2006)

  25. Hydro-shock Tangential discontinuity Slow-wave

  26. Jz @ t = 10 toroidal Bfrom Iz (“lobes”) “flux core: & Iz” (“helix/jet”) confinement (B2/8 ~ pgas)

  27. Lobes: Pressure Confinement and Nearly Force-Free

  28. Poloidal Current Iz Evolution Toroidal Flux Poloidal Flux z=0 Poloidal Flux z=6 Time

  29. Stability: with initial perturbations log(density) Poloidal Jz Nakamura, Li & Li (2006)

  30. Nakamura, Li & Li (2006)

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

  32. Jz = 1.5 Jz = -0.5 Combined

  33. KH Stable

  34. Perseus A426

  35. M87

  36. 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.

  37. 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. Why Plasma Astrophysics?

  38. Laboratory Magnetized Plasma Astrophysics

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

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

  41. Farady Rotation Measure Kronberg et al’03

  42. Thank you!