Radiative Magnetohydrodynamic
Accretion Flows and Jets
Yoshiaki Kato (Univ. of Tsukuba)
Ryoji Matsumoto (Chiba Univ.)
Shin Mineshige (Kyoto Univ.)
Kazunari Shibata (Kyoto Univ.)
Ken Ohsuga (RIKEN)
Masayuki Umemura (Univ. Tsukuba)Contents of my talk
• Non-Radiative MHD Accretion Flows and Jets
• Launching mechanism of Jets in MHD Accretion Flows• Quasi-Periodic Oscillations in MHD Accretion Flows• Radiation Transfer in MHD accretion flows• Examine the MHD accretion flow model by comparing theemergent spectra with the observed spectra in our galactic
center source, SgrA*.

Why we study
accretion flows and jets?

• Formation and Evolution of Supermassive Black Holes• Formation of Astrophysical Jets
• Large-scale structure• Heating of IGM• Radiative properties of AGNs
• Variability• Ionization of IGM• Heating of IGM

Launching Mechanism of Jets in
MHD Accretion Flows• Caveats in previous studies on launching jets:• Large-scale strong magnetic field lines permeating
accretion disks• Origin of such magnetic field lines is out of concern• Key questions:• Can magnetic fields associated with stars and accretion
disks produce jets?

• If so, how?

Magnetic-Tower Jets
(YK, Hayashi, Matsumoto 2004;YK, Mineshige, Shibata 2004)
Magnetosphere of Neutron Stars

Magnetized Accretion Flowsaround Black HolesThe magnetic tower jet solution is anuniversal mechanism which can produce
jets in dynamo-active accretion disks!!!

Quasi-Periodic Oscillations (QPOs)
in MHD accretion flows ( YK 2004)rs≈ 10−5 MBH /M" [sec]cz

ΔrEmission
10rs
Local mass fluxr
Radial mass fluxes
Vertical mass fluxes

40 rsTwin Quasi-Periodic Oscillationsin MHD Accretion Flows( YK 2004)

PSD as a function of radius

PSD integrated over the radius
Radial oscillations

Vertical oscillations

Radial oscillations

Resonant Global Disk Oscillations

Keplerian frequency

Early phase

Epicyclic frequency
Late phaseRadiation Transfer in MHD Accretion Flows(e.g., YK 2004; Ohsuga,YK, Mineshige 2005)rs≈ 10−5 MBH /M" [sec]c

MHD data:

z200x32x400 in cylindrical coord. → 200x200x200
meshes in Cartesian coord.
last 40 snapshots of quasi-steady MHD accretion flows (600 snapshots in total)

Free parameters:
Density and Black hole mass

Two-temperature plasma:Electron temperature is calculated self-consistently.

r

Radiation processes:
Synchrotron emission/absorption, (Inverse-)Compton scattering, and Bremsstrahlung
emission/absorption by thermal electrons

40 rs

Emergent SED ofMHD Accretion Flows(YK, Ohsuga, Umemura, Mineshige in prep.)
40

Emergent SED (time-averaged)38
log10 ν Lν [erg/sec]

3634

VLBI & VLA & VLT
Chandra: FS

SSpitzer

32
30
28

Chandra: QSSA

26
8

INTEGRAL

SSSC

B

Emitted SED (time-averaged)1012

14
16log10 ν [Hz]1820

Spatial Distribution of thePower of Escaping Photons(YK, Ohsuga, Umemura, Mineshige in prep.)

One-temperature plasma modelTwo-temperature plasma model

BHBHzzyx

20 rsyx

20 rs

Plasma model is crucial not only for evaluating
emission region but also for time variability

Summary• Magnetic fields associated with stars and disks can produce jets:• Magnetic loops connecting between differentially rotating
objects deform themselves into a magnetic-tower,• The magnetic-tower can drive jets and outflows.
• Resonant disk oscillations can be excited in MHD accretion flowsthat can account for quasi-periodic X-ray brightness oscillations in
X-ray binaries including micro-quasars:
QPOs trace the metric (the mass and the spin) of black holes.

•• Emergent SEDs can explain the observed SED in SgrA*:• Radiation transfer is inevitable for evaluating electron
temperature (e.g., two-temperature plasma),• Radiations in MHD flows can account for variable emissions inrecent NIR and X-ray observations in SgrA*.