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- Mami Machida
- 2002

We present the results of three-dimensional global resistive magnetohydro-dynamic (MHD) simulations of black hole accretion flows. General relativistic effects are simulated by using the pseudo-Newtonian potential. Initial state is an equilibrium model of a torus threaded by weak toroidal magnetic fields. As the magnetorotational instability (MRI) grows in… (More)

- Yasuo Fukui, Hiroaki Yamamoto, +11 authors Akira Mizuno
- Science
- 2006

The central few hundred parsecs of the Milky Way host a massive black hole and exhibit very violent gas motion and high temperatures in molecular gas. The origin of these properties has been a mystery for the past four decades. Wide-field imaging of the (12)CO (rotational quantum number J = 1 to 0) 2.6-millimeter spectrum has revealed huge loops of dense… (More)

We present the results of three-dimensional global magnetohydrodynamic (MHD) simulations of the Parker-shearing instability in a differentially rotating torus initially threaded by toroidal magnetic fields. An equilibrium model of magnetized torus is adopted as an initial condition. When β 0 = P gas /P mag ∼ 1 at the initial state, magnetic flux buoyantly… (More)

- H. Oda, M. Machida, K. E. Nakamura
- 2009

We present new thermal equilibrium solutions for optically thin and optically thick disks incorporating magnetic fields. The purpose of this paper is to explain the bright hard state and the bright/slow transition observed in the rising phases of outbursts in black hole candidates. On the basis of the results of three-dimensional MHD simulations, we assume… (More)

- Kunio Takahashi, Satoshi Nozawa, +5 authors Hiroaki Yamamoto
- 2009

We carried out two-dimensional magnetohydrodynamic simulations of the Galactic gas disk to show that the dense loop-like structures discovered by the Galactic center molecular cloud survey by NANTEN 4 m telescope can be formed by the buoyant rise of magnetic loops due to the Parker instability. At the initial state, we assumed a gravitationally stratified… (More)

We carried out global three-dimensional resistive magnetohydrodynamic simulations of galactic gaseous disks to investigate how the galactic magnetic fields are amplified and maintained. We adopt a steady axisymmetric gravitational potential given by Miyamoto & Nagai (1975) and Miyamoto, Satoh & Ohashi (1980). As the initial condition, we assume a warm (T ∼… (More)

We carried out three-dimensional global resistive magnetohydrodynamic (MHD) simulations of the cooling instability in optically thin hot black hole accretion flows by assuming bremsstrahlung cooling. General relativistic effects are simulated by using the pseudo-Newtonian potential. Cooling instability grows when the density of the accretion disk becomes… (More)

We construct a new family of analytic models of black hole accretion disks in dynamical equilibria. Our construction is based on assuming distributions of angular momentum and entropy. For a particular choice of the distribution of angular momentum, we calculate the shapes of equipressure surfaces. The equipressure surfaces we find are similar to those in… (More)

- Ryoji Matsumoto, Daikou Shiota, +8 authors Mami Machida
- 2006

By applying magnetohydrodynamic (MHD) codes implemented to the Earth Simulator, we carried out three-dimensional simulations of formation of astrophysical jets. We adopted a Cartesian MHD code to study the stability of magnetically driven jets launched from accretion disks. Numerical results indicate that although the magnetic field lines anchored to the… (More)

- M Machida, S Tanaka, K Nakamori
- Biomedical chromatography : BMC
- 1993

A simple, selective, reversed phase liquid chromatographic method using a column-switching technique has been developed for the simultaneous determination of a novel derivative of etoposide (NK611) and its O-demethyl metabolite in dog plasma. A good linear response was obtained for both drugs in the range 0.1-12.0 micrograms/mL. The mean recoveries were… (More)