4 th International MAXI Workshop Nov 30 Dec

4 th International MAXI Workshop Nov. 30 – Dec. 2, 2010 Global Magnetohydrodynamic Simulations of State Transitions in Black Hole Candidates Ryoji Matsumoto (Chiba Univ. ) Collaborators: Takayuki Ogawa , Tomohisa Kawashima (Chiba Univ. ) Hiroshi Oda (Shanghai Obs. ), and Mami Machida (Kyushu Univ. )

Activities of Black Hole Candidates X-ray light curve of Cyg X-1 (Negoro 1995) AGN Jets (NGC 4261) Makita and Matsuda SS 433 Jet Microquasar GRS 1915+105 Mirabel and Rodriguez 1998

Magnetic Activities of Accretion Disks Magnetic fields play essential roles in the angular momentum transport which enables the accretion and release of the gravitational energy 3

Magneto-rotational Instability：MRI Angular momentum Balbus and Hawley (1991), Velikhov (1959)

Three-dimensional Global MHD Simulations of Black Hole Accretion Disks Initial state t=26350 　unit time t 0=rg/c Machida and Matsumoto 2003

Outflows from Accretion Disks 6

Structure of the Launching Region of the Outflow Isosurface of vz=0. 05 c Machida and Matsumoto 2008 Magnetic field lines and azimuthal magnetic field 7

How a Black Hole Looks Like

State Transitions in Black Hole Candidates

State Transitions Observed in XTE J 1752 -223 1/21 Jet ejection Nakahira et al. 2010 MAXI Science News #17

Evolution of Outbursts in Hardness-Intensity Diagram Remillard 2005 Hard state Soft state 10 10 100 Ke. V Optically thick cold disk ○　XTE J 1752 -223　 100 Ke. V Optically thin hot disk

Classical Accretion Disk Models give too Low Transition Luminosity Solid Curves : Thermal Equilibrium Curves (Abramowicz et al. 1995)

Three-Dimensional MHD Simulation including Optically Thin Cooling Radiative Cooling : Qrad = Qb r 2 T 1/2 density temperature Toroidal field Machida et al. 2006, PASJ 58, 193

Time Evolution β=Pgas/Pmag 14

Formation of a Magnetically Supported Disk Before the transition After the transition Machida, Nakamura and Matsumoto 2006 15

Schematic Picture of the Growth of the Cooling Instability Radiative Cooling 　b ~ 10 Optically Thin Hot Disk Supported by Gas Pressure Cool Down 　b < 1 Optically Thin Cool Disk Supported by Magnetic Pressure Final state after the onset of the cooling instability depends on the total azimuthal magnetic flux 16

Thermal Equilibrium Curves including Azimuthal Magnetic Fields Oda et al. 2009

Evolution of an Accretion Disk Steady Model （Oda et al. 2009） XTE J 1752 -223 （Nakahira et al. 2010)

Development of Next Generation MHD Simulator for Accretion Disks Optimization for Parallel Computers Platform of MHD Simulator : CANS Riemann Solvers Simulation Engine Simulation Examples Simulation Analysis Relativistic MHD Radiation MHD Web Page Visualization Application to Accretion Disks Time Variation of RIAF Hard to Soft State Transition Evolution of Formation of Soft/Slim Relativistic Disks Jets

From HD/MHD to Radiation MHD HD 3 D Mesh Finite Difference 3 D ρ(t, x, y, z), v(t, x, y, z), P(t, x, y, z) Cost ∝N 3×Nstep MHD +B(t, x, y, z) Radiation MHD + Ｉ (t, x, y, z, n, q, f) Flux Limited Diffusion Ｂ Ｉ Solve Radiation Transfer N 6×Nstep

Basic Equations Interaction with radiation

Global Radiation MHD Simulation Takeuchi, Ohsuga, and Mineshige 2010 SS 433 Axisymmetric 2 D Radiation MHD Simulation We are extending this simulation to 3 D Radiation MHD

Accretion Disk Dynamos and Quasi-Periodic Oscillations Optical image of sunspots by HINODE X-ray Image by HINODE Satellite Butterfly Diagram of Sunspots (NASA)

Power Density Quasi-Periodic Oscillations （ＱＰＯs） in Black Hole Candidates 0. 01 0. 1 1 10 GX 339 -4 100 Hz 0. 01 0. 1 1 10 100 Hz XTE J 1550 -564 Mc. Clintock and Remillard 2004

Local 3 D MHD Simulation White ：β＝１ Black ：　dln|B|/dz < 0　 Time Variation of Azimuthal Magnetic Fields Quasi periodic reversal in time scale of 10 rotation 25 (Shi, Krolik, and Hirose 2010)

How Azimuthal Magnetic Field Reverses ? MRI ＋１ Growth of MRI ＋２ －１ Parker Instability Buoyant escape of magnetic flux ＋２ Buoyant rise －１

QPOs Appear during the Hard-to-Soft Transition QPOs Solid Curves : Thermal Equilibrium Curves (Abramowicz et al. 1995)

Formation of an Inner Torus and QPOs for Cool Accretion Flow Low frequency QPO Formation of the inner torus is essential for QPOs High temperature(HT) model QPO period is about 10 Low temperature (LT) rotation of the inner torus model Machida and Matsumoto 2008

Radial Distribution of Oscillation Model HT Model LT Machida et al. 2008

Summary • Global 3 D MHD simulations enabled us to study the evolution of an accretion disk without assuming the alpha-viscosity • During the hard-to-soft transition, magnetically supported, cool disk is formed. This disk can explain the luminous hard state observed in black hole candidates • Global 3 D Radiation MHD simulations will reveal the mechanism of transitions to the soft state • Disk dynamo can generate low frequency QPOs

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