Mami MACHIDA

J-GLOBAL         Last updated: Feb 20, 2019 at 11:37
 
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Name
Mami MACHIDA
Affiliation
Kyushu University
Section
Faculty of Sciences, Department of Physics
Job title
Resarch assistant

Research Interests

 
 

Research Areas

 
 

Published Papers

 
Marijke Haverkorn, Mami Machida, Takuya Akahori
Galaxies   7    Jan 2019
© 2019 by the authors. This article summarizes the work presented at the workshop "The Power of Faraday Tomography: towards 3D mapping of cosmic magnetic fields", held in Miyazaki, Japan, in Spring 2018. We place the various oral and poster presen...
Kenji E. Nakamura, Mami Machida, Ryoji Matsumoto
Galaxies   7    Jan 2019   [Refereed]
© 2019 by the authors. Thermal conduction plays an important role in bimodal accretion flows consisting of hightemperature flow and cool flow, especially when the temperature is high and/or has a steep gradient. For example, in hard-to-soft transi...
Takumi Ohmura, Mami Machida, Kenji Nakamura, Yuki Kudoh, Yuta Asahina, Ryoji Matsumoto
Galaxies   7    Jan 2019   [Refereed]
© 2019 by the authors. In astrophysical jets observed in active galactic nuclei and in microquasars, the energy exchange rate by Coulomb collision is insufficient for thermal equilibrium between ions and electrons. Therefore, it is necessary to co...
Mami Machida, Takuya Akahori, Kenji E. Nakamura, Hiroyuki Nakanishi, Marijke Haverkorn
Galaxies   7    Jan 2019   [Refereed]
© 2019 by the authors. Magnetic fields in the universe play an essential role in observations of the radio synchrotron continuum; however, we do not know enough about them, either observationally or theoretically. We are interested in galactic mag...
Haruka Sakemi, Mami Machida, Takumi Ohmura, Shinsuke Ideguchi, Yoshimitsu Miyashita, Keitaro Takahashi, Takuya Akahori, Hiroki Akamatsu, Hiroyuki Nakanishi, Kohei Kurahara, Jamie Farnes
Galaxies   6(4)    Dec 2018   [Refereed]
© 2018 by the authors. A jet termination region provides us with useful information about how a jet interacts with the interstellar medium. Identifying the strength and orientation of magnetic fields at the terminal is crucially important to under...
Mami Machida, Takuya Akahori, Kenji Nakamura, Hiroyuki Nakanishi, Marijke Haverkorn
   Nov 2018   [Refereed]
Observational study of galactic magnetic fields is limited by projected
observables. Comparison with numerical simulations is helpful to understand the
real structures, and observational visualization of numerical data is an
important task. Machid...
M. Machida, T. Akahori, T. Akahori, K. E. Nakamura, H. Nakanishi, H. Nakanishi, H. Nakanishi, M. Haverkorn
Monthly Notices of the Royal Astronomical Society   480 17-25   Oct 2018   [Refereed]
© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. Observational study of galactic magnetic fields is hampered by the fact that the observables only probe various projections of the magnetic fie...
Haruka Sakemi, Mami Machida, Takuya Akahori, Hiroyuki Nakanishi, Hiroki Akamatsu, Kohei Kurahara, Jamie Farnes
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   70(2)    Feb 2018   [Refereed]
We report a polarization analysis of the eastern region of W50, observed with
the Australia Telescope Compact Array (ATCA) at 1.4 - 3.0 GHz. In order to
study the physical structures in the region where the SS433 jet and W50
interact, we obtain an...
Kensuke Kakiuchi, Takeru K. Suzuki, Yasuo Fukui, Kazufumi Torii, Rei Enokiya, Mami Machida, Ryoji Matsumoto
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   476(4) 5629-5638   Dec 2017   [Refereed]
We studied roles of the magnetic field on the gas dynamics in the Galactic
bulge by a three-dimensional global magnetohydrodynamical simulation data,
particularly focusing on vertical flows that are ubiquitously excited by
magnetic activity. In lo...
Takuya Akahori, Hiroyuki Nakanishi, Yoshiaki Sofue, Yutaka Fujita, Kiyotomo Ichiki, Shinsuke Ideguchi, Osamu Kameya, Takahiro Kudoh, Yuki Kudoh, Mami Machida, Yoshimitsu Miyashita, Hiroshi Ohno, Takeaki Ozawa, Keitaro Takahashi, Motokazu Takizawa, Dai G. Yamazaki
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   70(1)    Sep 2017   [Refereed]
Magnetic field is ubiquitous in the Universe and it plays essential roles in
various astrophysical phenomena, yet its real origin and evolution are poorly
known. This article reviews current understanding of magnetic fields in the
interstellar med...
Kensuke Kakiuchi, Takeru K. Suzuki, Yasuo Fukui, Kazufumi Torii, Mami Machida, Ryoji Matsumoto
   Oct 2016
The vertical flow structure in the galactic center region remains poorly
understood. We analyzed the MHD simulation data by Suzuki et al. (2015) for
better understanding. As a result, we found the fast downflows with a speed of
~100 km/s near the ...
Takeru K. Suzuki, Yasuo Fukui, Kazufumi Torii, Mami Machida, Ryoji Matsumoto, Kensuke Kakiuchi
   Sep 2016
By performing a global magnetohydrodynamical (MHD) simulation for the Milky
Way with an axisymmetric gravitational potential, we propose that spatially
dependent amplification of magnetic fields possibly explains the observed
noncircular motion of...
Takuya Akahori, Yutaka Fujita, Kiyotomo Ichiki, Shinsuke Ideguchi, Takahiro Kudoh, Yuki Kudoh, Mami Machida, Hiroyuki Nakanishi, Hiroshi Ohno, Takeaki Ozawa, Keitaro Takahashi, Motokazu Takizawa, for the SKA-JP Magnetism SWG
   Mar 2016
Magnetic fields play essential roles in various astronomical objects. Radio
astronomy has revealed that magnetic fields are ubiquitous in our Universe.
However, the real origin and evolution of magnetic fields is poorly proven. In
order to advance...
Takeru K. Suzuki, Yasuo Fukui, Kazufumi Torii, Mami Machida, Ryoji Matsumoto
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   454(3) 3049-3059   Apr 2015   [Refereed]
By performing a global magneto-hydrodynamical simulation for the Milky Way
with an axisymmetric gravitational potential, we propose that spatially
dependent amplification of magnetic fields possibly explains the observed
noncircular motion of the ...
Mami Machida, Kenji E. Nakamura, Takahiro Kudoh, Takuya Akahori, Sofue Yoshiaki, Ryoji Matsumoto
ASTROPHYSICAL JOURNAL   764(1)    Jan 2013   [Refereed]
We carried out global three-dimensional magneto-hydrodynamic simulations of
dynamo activities in galactic gaseous disks without assuming equatorial
symmetry. Numerical results indicate the growth of azimuthal magnetic fields
non-symmetric to the e...
Hiroshi Oda, Mami Machida, Kenji E. Nakamura, Ryoji Matsumoto, Ramesh Narayan
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   64(1)    Sep 2011   [Refereed]
We present global solutions of optically thin, two-temperature black hole
accretion disks incorporating magnetic fields. We assume that the
{\pi}{\phi}-component of the Maxwell stress is proportional to the total
pressure, and prescribe the radial...
Molecular Loops in the Galactic Center - The Physical Condition in the Whole Loops
Kudo Natsuko, Torii Kazufumi, Machida Mami, Takahashi Kunio, Nozawa Satoshi, Yamamoto Hiroaki, Okuda Takeshi, Kawamura Akiko, Mizuno Norikazu, Onishi Toshikazu, Matsumoto Ryoji, Fukui Yasuo
GALACTIC CENTER: A WINDOW TO THE NUCLEAR ENVIRONMENT OF DISK GALAXIES   439 69-+   2011   [Refereed]
Molecular Loops in the Galactic Center: Detailed Observations of the Footpoint of the Loops
Torii Kazufumi, Fukui Yasuo, Kudo Natsuko, Yamamoto Hiroaki, Kawamura Akiko, Machida Mami, Takahashi Kunio, Nozawa Satoshi, Matsumoto Ryoji
GALACTIC CENTER: A WINDOW TO THE NUCLEAR ENVIRONMENT OF DISK GALAXIES   439 71-+   2011   [Refereed]
Three-Dimensional Global MHD Simulations of the Magnetic Loop Structures in our Galactic Center
Machida Mami, Matsumoto Ryoji, Nozawa Satoshi, Takahashi Kunio, Torii Kazufumi, Kudo Natsuko, Fukui Yasuo
GALACTIC CENTER: A WINDOW TO THE NUCLEAR ENVIRONMENT OF DISK GALAXIES   439 65-+   2011   [Refereed]
Molecular Loops in the Galactic Center
Fukui Yasuo, Torii Kazufumi, Kudo Natsuko, Yamamoto Hiroaki, Kawamura Akiko, Machida Mami, Takahashi Kunio, Nozawa Satoshi, Matsumoto Ryoji
GALACTIC CENTER: A WINDOW TO THE NUCLEAR ENVIRONMENT OF DISK GALAXIES   439 61-+   2011   [Refereed]
Natsuko Kudo, Kazufumi Torii, Mami Machida, Timothy A. Davis, Kazuki Tsutsumi, Motusuji Fujishita, Nayuta Moribe, Hiroaki Yamamoto, Takeshi Okuda, Akiko Kawamura, Norikazu Mizuno, Toshikazu Onishi, Hiroyuki Maezawa, Akira Mizuno, Kunihiko Tanaka, Nobuyuki Yamaguchi, Hajime Ezawa, Kunio Takahashi, Satoshi Nozawa, Ryoji Matsumoto, Yasuo Fukui
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   63(1) 171-197   Nov 2010   [Refereed]
We have carried out 12CO(J =2-1) and 12CO(J =3-2) observations at spatial
resolutions of 1.0-3.8 pc toward the entirety of loops 1 and 2 and part of loop
3 in the Galactic center with NANTEN2 and ASTE. These new results revealed
detailed distribut...
Yoshiaki Sofue, Mami Machida, Takahiro Kudoh
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   62(5) 1191-1201   Jun 2010   [Refereed]
We propose a primordial-origin model for the composite configurations of
global magnetic fields in spiral galaxies. We show that uniform tilted magnetic
field wound up into a rotating disk galaxy can evolve into composite magnetic
configurations c...
Hiroshi Oda, Mami Machida, Kenji E. Nakamura, Ryoji Matsumoto
   Feb 2010
We obtained thermal equilibrium solutions for optically thin, two-temperature
black hole accretion disks incorporating magnetic fields. The main objective of
this study is to explain the bright/hard state observed during the bright/slow
transition...
Kazufumi Torii, Natsuko Kudo, Motosuji Fujishita, Tokuichi Kawase, Takeshi Okuda, Hiroaki Yamamoto, Akiko Kawamura, Norikazu Mizuno, Toshikazu Onishi, Mami Machida, Kunio Takahashi, Satoshi Nozawa, Ryoji Matsumoto, Juergen Ott, Kunihiko Tanaka, Nobuyuki Yamaguchi, Hajime Ezawa, Juergen Stutzki, Frank Bertoldi, Bon-Chul Koo, Leonardo Bronfman, Michael Burton, Arnold Benz, Hideo Ogawa, Yasuo Fukui
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   62(3) 675-695   Sep 2009   [Refereed]
Fukui et al. (2006) discovered two molecular loops in the Galactic center and
argued that the foot points of the molecular loops, two bright spots at both
loops ends, represent the gas accumulated by the falling motion along the
loops, subsequent ...
Kazufumi Torii, Natsuko Kudo, Motosuji Fujishita, Tokuichi Kawase, Hiroaki Yamamoto, Akiko Kawamura, Norikazu Mizuno, Toshikazu Onishi, Akira Mizuno, Mami Machida, Kunio Takahashi, Satoshi Nozawa, Ryoji Matsumoto, Yasuo Fukui
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   62(5) 1307-1332   Jun 2009   [Refereed]
Fukui et al. (2006) discovered two huge molecular loops in the Galactic
center located in (l, b) ~ (355 deg-359 deg, 0 deg-2 deg) in a large velocity
range of -180-40 km s^-1. Following the discovery, we present detailed
observational properties o...
Motosuji Fujishita, Kazufumi Torii, Natsuko Kudo, Tokuichi Kawase, Hiroaki Yamamoto, Akiko Kawamura, Norikazu Mizuno, Toshikazu Onishi, Akira Mizuno, Mami Machida, Kunio Takahashi, Satoshi Nozawa, Ryoji Matsumoto, Yasuo Fukui
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   61(5) 1039-1053   Jun 2009   [Refereed]
We have discovered a molecular dome-like feature towards Tex and Tex. The large velocity
dispersions of 50--100 km sTex of this feature are much larger than those
in the Galactic ...
Kunio Takahashi, Satoshi Nozawa, Ryoji Matsumoto, Mami Machida, Yasuo Fukui, Natsuko Kudo, Kazufumi Torii, Hiroaki Yamamoto, Motosuji Fujishita
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   61(5) 957-969   May 2009   [Refereed]
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 ...
Mami Machida, Ryoji Matsumoto, Satoshi Nozawa, Kunio Takahashi, Yasuo Fukui, Natsuko Kudo, Kazufumi Torii, Hiroaki Yamamoto, Motosuji Fujishita, Kohji Tomisaka
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   61(3) 411-420   Dec 2008   [Refereed]
A survey for the molecular clouds in the Galaxy with NANTEN mm telescope has
discovered molecular loops in the Galactic center region. The loops show
monotonic gradients of the line of sight velocity along the loops and the large
velocity dispersi...
Mami Machida, Ryoji Matsumoto
PASJ, Vol.60, No.3 (2008) 613-626   60(3) 613-626   Feb 2008   [Refereed]
We present the results of global three dimensional magneto-hydrodynamic
simulations of black hole accretion flows. We focus on the dependence of
numerical results on the gas temperature Tout supplied from the outer region.
General relativistic eff...
Matsumoto Ryoji, Nishikori Hiromitsu, Tanaka Minoru, Machida Mami
MAPPING THE GALAXY AND NEARBY GALAXIES   71-+   2008   [Refereed]
Oda Hiroshi, Machida Mami, Nakamura Kenji E., Matsumoto Ryoji
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   59(2) 457-465   Apr 2007   [Refereed]
Oda Hiroshi, Machida Mami, Nakamura Kenji E., Matsumo Ryoji
ASTROPHYSICS OF COMPACT OBJECTS   968 408-+   2007   [Refereed]
Fukui Yasuo, Yamamoto Hiroaki, Fujishita Motosuji, Kudo Natsuko, Torii Kazufumi, Nozawa Satoshi, Takahashi Kunio, Matsumoto Ryoji, Machida Mami, Kawamura Akiko, Yonekura Yoshinori, Mizuno Norikazu, Onishi Toshikazu, Mizuno Akira
SCIENCE   314(5796) 106-109   Oct 2006   [Refereed]
Hiromitsu Nishikori, Mami Machida, Ryoji Matsumoto
Astrophys.J. 641 (2006) 862-877      Jan 2006
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 ...
Mami Machida, Kenji Nakamura, Ryoji Matsumoto
   Nov 2005
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 u...
Mami Machida, Ryoji Matsumoto
Astrophys.J. 585 (2003) 429-442      Nov 2002   [Refereed]
We present the results of three-dimensional global resistive
magnetohydrodynamic (MHD) simulations of black hole accretion flows. General
relativistic effects are simulated by using the pseudo-Newtonian potential.
Initial state is an equilibrium m...
Mami Machida, Ryoji Matsumoto, and Shin Mineshige
   Sep 2000
Outflows and convective motions in accretion flows have been intensively
discussed recently in the context of advection-dominated accretion flow (ADAF)
based on two-dimensional (2D) and three-dimensional (3D) hydrodynamical
simulations. We, howeve...

Misc

 
Lei Qian, Lei Qian, M. A. Abramowicz, M. A. Abramowicz, P. C. Fragile, P. C. Fragile, J. Horák, J. Horák, M. MacHida, O. Straub, O. Straub
Astronomy and Astrophysics   498 471-477   May 2009
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 momentu...
H. Oda, M. MacHida, K. E. Nakamura, R. Matsumoto
Astrophysical Journal   697 16-28   Jan 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 ...
H. Yamamoto, Y. Fukui, M. Fujishita, K. Torii, N. Kudo, S. Nozawa, K. Takahashi, K. Takahashi, R. Matsumoto, M. MacHida, A. Kawamura, Y. Yonekura, N. Mizuno, T. Onishi, A. Mizuno
Proceedings of the International Astronomical Union   2 501   Aug 2006
The new molecular image obtained by NANTEN telescope in the galactic center has revealed the existence of the two loop like structures, loop 1 and loop 2, which have never been seen before toward l = 355 to 358. The velocities of loop 1 and loop 2...
H. Oda, K. E. Nakamura, M. MacHida, R. Matsumoto
Proceedings of the International Astronomical Union   2 421-422   Aug 2006
We obtained steady solutions of optically thin two-temperature magnetized accretion disks around a black hole. We included relativistic bremsstrahlung cooling, synchrotron cooling and inverse Compton effects and assumed that the disk is threaded b...
Ryoji Matsumoto, Mami MacHida
Proceedings of the International Astronomical Union   2 37-42   Aug 2006
We studied the origin of quasi-periodic oscillations (QPOs) of X-rays in black hole candidates by three-dimensional global resistive magnetohydrodynamic simulations of accretion disks. Initial state is a rotating disk threaded by weak toroidal mag...
Mami MacHida, Ryoji Matsumoto
Proceedings of the International Astronomical Union   2 405-406   Aug 2006
We present the results of global 3D MHD simulations of optically thin black hole accretion flows. The initial disk is embedded in a low density, spherical, isothermal halo and threaded by weak ( Pgas/Pmag = 100) toroidal magnetic field. General re...
Hiromitsu Nishikori, Mami MacHida, Ryoji Matsumoto
AIP Conference Proceedings   784 786-791   Sep 2005
We present the results of global three dimensional magnetohydrodynamic simulations of galactic gaseous disks. For the gravitational potential we adopt a model of our galaxy including dark matter given by Miyamoto et al. (1980). The initial gas dis...
Minoru Tanaka, Keiichi Wada, Mami MacHida, Ryoji Matsumoto, Shigeki Miyaji
AIP Conference Proceedings   784 792-797   Sep 2005
We studied the stability of galactic spiral shocks through two dimensional global magnetohydrodynamic simulations. Recently, Wada & Koda (2003) showed, using global hydrodynamic simulations, that galactic gas flows behind a spiral shock becomes un...
Mami Machida, Ryoji Matsumoto
Progress of Theoretical Physics Supplement   155 371-372   Jan 2004
We analysed the results of long time-scale global three-dimensional resistive magneto-hydrodynamic simulations of radiatively inefficient accretion flows onto a black hole. We found that the power spectral density (PSD) of the time variation of th...
Mami Machida, Kenji Nakamura, Ryoji Matsumoto
Publications of the Astronomical Society of Japan   56 671-679   Jan 2004
We studied the global structures of radiatively inefficient black hole accretion flows by three-dimensional magnetohydrodynamic simulations. The initial state is a constant angular-momentum torus threaded by weak toroidal magnetic fields. The toru...
Ryoji Matsumoto, Mami Machida, Kenji Nakamura
Progress of Theoretical Physics Supplement   155 124-131   Jan 2004
We present the results of global three-dimensional resistive magnetohydrodynamic simulations of optically thin accretion disks around a black hole. General relativistic effects are simulated by using the pseudo-Newtonian potential. Initial state i...
Shin Mineshige, Takashi Hosokawa, Mami Machida, Ryoji Matsumoto
Publications of the Astronomical Society of Japan   54 655-660   Jan 2002
The detectability of gravitational-wave (GW) radiation from accretion disks is discussed based on various astrophysical contexts. In order to emit GW radiation, the disk shape should lose axial symmetry. We point out that a significant deformation...
Mami Machida, Ryoji Matsumoto, Shin Mineshige
Publications of the Astronomical Society of Japan   53    Dec 2001
Two-dimensional (2D) and three-dimensional (3D) hydrodynamical simulation have been intensively performed recently to clarify the accretion-flow structure in the low-radiation-efficiency limit. However, the results depend critically on the paramet...
K. E. Nakamura, K. E. Nakamura, R. Matsumoto, M. Machida, W. Chou
Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias   9 99-100   Dec 2000
We are developing an astrophysical rotating plasma simulator, which consists of reusable modules plugged-in to a platform of a 3-dimensional magnetohydrodynamical code. Modules incorporating magnetic diffusion, thermal conduction, radiative coolin...
M. Machida, Mitsuru R. Hayashi, R. Matsumoto
Astrophysical Journal   532    Mar 2000
We present the results of three-dimensional global magnetohydrodynamic simulations of the Parker-shearing instability in a differentially rotating torus initially threaded by toroidal magnetic fields. An equilibrium model of a magnetized torus is ...
Mami Machida, Ryoji Matsumoto, Shigeki Miyaji, Kenji E. Nakamura, Hideaki Tonooka
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)   1940 328-335   Jan 2000
© Springer-Verlag Berlin Heidelberg 2000. We present numerical results of three-dimensional global magneto-hydrodynamic (MHD) simulations achieved on Astrophysical Rotating Plasma Simulator (ARPS) developed at Chiba University. We simulate the tim...
Toshihiro Kawaguchi, Shin Mineshige, Mami Machida, Ryoji Matsumoto, Kazunari Shibata
Publications of the Astronomical Society of Japan   52    Jan 2000
Rapid fluctuation with a frequency dependence of 1/fα (with α ≃ 1-2) is characteristic of radiation from black-hole objects. Its origin remains poorly understood. We examined three-dimensional magnetohydrodynamical simulation data, finding that a ...
Ryoji Matsumoto, Mami Machida, Mitsuru Hayashi, Kazunari Shibata
Progress of Theoretical Physics Supplement   632-637   Jan 2000
We present the results of three-dimensional global magnetohydrodynamic (MHD) simulations of differentially rotating astrophysical disks. We simulate the time evolution of the disk by using a parallelized three-dimensional MHD code. Typical number ...

Research Grants & Projects

 
State transitions in X-ray black hole binaries