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.)

4th International MAXI Workshop Nov. 30 – Dec. 2, 2010

Activities of Black Hole Candidates

Makita and Matsuda

X-ray light curve of Cyg X-1 (Negoro 1995)

Microquasar GRS1915+105

AGN Jets (NGC4261)

SS433 JetMirabel and Rodriguez 1998

Magnetic Activities of Accretion Disks

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

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 t0=rg/c

Machida and Matsumoto 2003

Outflows from Accretion Disks

6

7

Structure of the Launching Region of the Outflow

Isosurface of vz=0.05c Magnetic field lines and azimuthal magnetic field

Machida and Matsumoto 2008

How a Black Hole Looks Like

State Transitions in Black Hole Candidates

State Transitions Observed in XTE J1752-223

Nakahira et al. 2010 MAXI Science News #17

1/21

Jetejection

Evolution of Outbursts in Hardness-Intensity Diagram

Remillard 2005

Hard state

10 100KeV

Soft state

10 100KeV

Optically thick cold disk

Optically thin hot disk○ 　 XTE J1752-223 　

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 T1/2

density temperature Toroidal field

Machida et al. 2006, PASJ 58, 193

14

Time Evolution

β=Pgas/Pmag

15

Formation of a Magnetically Supported Disk

Before the transition After the transition

Machida, Nakamura and Matsumoto 2006

16

Schematic Picture of the Growth of the Cooling Instability

Cool Down

Optically Thin Hot Disk Supported by Gas Pressure

Radiative Cooling

　 ~ 10

Optically Thin Cool Disk Supported by Magnetic Pressure

　 < 1

Final state after the onset of the cooling instability depends on the total azimuthal magnetic flux

Thermal Equilibrium Curves including Azimuthal Magnetic Fields

Oda et al. 2009

Evolution of an Accretion Disk

Steady Model （ Oda et al. 2009 ）

XTE J1752-223 （ Nakahira et al. 2010)

Development of Next Generation MHD Simulator for Accretion Disks

Simulation Engine

Platform of MHD Simulator : CANS

Simulation Examples

Simulation Analysis

Radiation MHD

Web Page Visualization

Optimization for Parallel Computers

Riemann Solvers

Relativistic MHD

Application to Accretion Disks

Time Variation of RIAF

Hard to Soft State Transition

Evolution of Soft/Slim Disks

Formation of Relativistic Jets

From HD/MHD to Radiation MHD

HD 3D

Ｂ

MHD

Radiation MHD

N6×Nstep

+ Ｉ (t,x,y,z)

Cost ∝ N3×Nstep

ρ(t,x,y,z), v(t,x,y,z), P(t,x,y,z)

+B(t,x,y,z)

ＩSolve Radiation Transfer

3D MeshFinite Difference

Flux Limited Diffusion

Basic Equations

00000

0

0

:4

4)ε(∂

ε∂

η

4

)∇(∇)∇(

∂

∂

0)(∂

ρ∂

PvFv

vv

BBvB

FgBB

vvv

v

EcBEt

E

EcBQQpρt

ρt

cρ

πpρ

tρ

ρt

visJ

－

Interaction with radiation

Global Radiation MHD Simulation

Takeuchi, Ohsuga, and Mineshige 2010 SS433

Axisymmetric 2D Radiation MHD Simulation

We are extending this simulation to 3D Radiation MHD

Accretion Disk Dynamos and Quasi-Periodic Oscillations

X-ray Image by HINODE SatelliteButterfly Diagram of Sunspots (NASA)

Optical image of sunspots by HINODE

Quasi-Periodic Oscillations （ＱＰＯ s ） in Black Hole

Candidates

Pow

er D

ensi

ty

0.1 1 10 1000.01 Hz

GX 339-4

0.1 1 10 1000.01 Hz

XTE J1550-564

McClintock and Remillard 2004

Local 3D MHD Simulation

(Shi, Krolik, and Hirose 2010) 25

Time Variation of Azimuthal Magnetic Fields

White ： β ＝１Black ：　 dln|B|/dz < 0 　

Quasi periodic reversal in time scale of 10 rotation

How Azimuthal Magnetic Field Reverses ?

Growth of MRI

＋１

＋２

－１

Buoyant escape of magnetic flux

＋２

－１

Buoyant rise

MRI

Parker Instability

QPOs Appear during the Hard-to-Soft Transition

QPOs

Solid Curves : Thermal Equilibrium Curves (Abramowicz et al. 1995)

High temperature(HT) model

Low temperature (LT) model

Formation of an Inner Torus and QPOs for Cool Accretion Flow

Formation of the inner torus is essential for QPOs

Machida and Matsumoto 2008

Low frequency QPO

QPO period is about 10 rotation of the inner torus

Radial Distribution of Oscillation

Model HT Model LT

Machida et al. 2008

Summary

• Global 3D 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 3D Radiation MHD simulations will reveal the mechanism of transitions to the soft state

• Disk dynamo can generate low frequency QPOs

END

Thank You