The influence of initial mass segregation on the runaway merging of stars (2008)
Ardi, Eliani, Baumgardt, Holger, Mineshige, Shin
We have investigated the effect of initial mass segregation on the runaway merging of stars. The evolution of multi-mass, dense star clusters was followed by means of direct N-body simulations of up...
X-ray Emissions from Three-dimensional Magnetohydrodynamic Coronal Accretion Flows (2008)
Kawanaka, Norita, Kato, Yoshiaki, Mineshige, Shin
We calculate the radiation spectrum and its time variability of the black hole accretion disk-corona system based on the three-dimensional magnetohydrodynamic simulation. In explaining the spectral...
On Black Hole Mass Estimation from X-ray Spectra of Ultraluminous X-ray Sources (2007)
Vierdayanti, Kiki, Watarai, Ken-ya, Mineshige, Shin
We propose a methodology to derive a black-hole mass for super-critical accretion flow. Here, we use the extended disk blackbody (extended DBB) model, a fitting model in which the effective...
Why Is Supercritical Disk Accretion Feasible? (2007)
Although the occurrence of steady supercritical disk accretion onto a black hole has been speculated about since the 1970s, it has not been accurately verified so far. For the first time, we...
A supermassive binary black hole with triple disks (2007)
Hayasaki, Kimitake, Mineshige, Shin, Ho, Luis C.
Hierarchical structure formation inevitably leads to the formation of supermassive binary black holes (BBHs) with a sub-parsec separation in galactic nuclei. However, to date there has been no...
Modeling Dense Stellar Systems (2007)
Hut, Piet, Mineshige, Shin, Heggie, Douglas C., Makino, Junichiro
Black holes and neutron stars present extreme forms of matter that cannot be created as such in a laboratory on Earth. Instead, we have to observe and analyze the experiments that are ongoing in the...
Neutrino Cooled Disk and Its Stability (2007)
Kawanaka, Norita, Mineshige, Shin
We investigate the structure and stability of hypercritical accretion flows around stellar-mass black holes, taking into account neutrino cooling, lepton conservation, and firstly a realistic...
Hayasaki, Kimitake, Mineshige, Shin, Sudou, Hiroshi
We investigate the accretion flows onto the supermassive binary black holes (SMBBHs) from the circumbinary disk with the equal mass, eccentric binary on the subparsec scale, using Smoothed Particle...
The core radius of a star cluster containing a massive black hole (2006)
Heggie, Douglas C., Hut, Piet, Mineshige, Shin, Makino, Jun, Baumgardt, Holger
(Simplified) We present a theoretical framework which establishes how the core radius of a star cluster varies with the mass of an assumed central black hole. Our result is that the ratio of core to...
Binary Black Hole Accretion Flows in Merged Galactic Nuclei (2006)
Hayasaki, Kimitake, Mineshige, Shin, Sudou, Hiroshi
We study the accretion flows from the circumbinary disks onto the supermassive binary black holes in a subparsec scale of the galactic center, using a smoothed particles hydrodynamics (SPH) code....
Do Ultraluminous X-ray Sources Really Contain Intermediate-mass Black Holes? (2006)
Vierdayanti, Kiki, Mineshige, Shin, Ebisawa, Ken, Kawaguchi, Toshihiro
An open question remains whether Ultraluminous X-ray Sources (ULXs) really contain intermediate-mass black holes (IMBHs). We carefully investigated the XMM-Newton EPIC spectra of the four ULXs that...
Collimated Jet or Expanding Outflow: Possible Origins of GRBs and X-Ray Flashes (2006)
Mizuta, Akira, Yamasaki, Tatsuya, Nagataki, Shigehiro, Mineshige, Shin
We investigate the dynamics of an injected outflow propagating in a progenitor in the context of the collapsar model for gamma-ray bursts (GRBs) through two dimensional axisymmetric relativistic...
Collimated jet or expanding outflow: possible origins of gamma-ray bursts and X-ray flashes (2006)
Mizuta, Akira, Yamasaki, Tatsuya, Nagataki, Shigehiro, Mineshige, Shin
Wang, Jian-Min, Watarai, Ken-Ya, Mineshige, Shin
We compile a sample consisting of 56 radio-quiet active galactic nuclei so as to investigate statistical properties of hot corona of accretion disks from {\em ASCA} observations. The black-hole...
Where is a Marginally Stable Last Circular Orbit in Super-Critical Accretion Flow? (2003)
Watarai, Ken-ya, Mineshige, Shin
Impressed by the widespread misunderstanding of the issue, we return to the old question of the location of the inner edge of accretion disk around black hole. We recall the fundamental results...
Kato, Yoshiaki, Mineshige, Shin, Shibata, Kazunari
We present three-dimensional (3-D) magnetohydrodynamical (MHD) simulations of radiatively inefficient accretion flow around black holes. General relativistic effects are simulated by using the...
Watarai, Ken-ya, Mineshige, Shin
To understand the bursting behavior of the microquasar GRS 1915+105, we calculate time evolution of a luminous, optically thick accretion disk around a stellar mass black hole undergoing limit-cycle...
A New Method to Map Flares in Quasars (2003)
Yonehara, Atsunori, Mineshige, Shin, Takei, Yoh, Chartas, George, Turner, Edwin L.
Recently, Chartas et al. (2001) detected a rapid X-ray flare in the gravitationally lensed, multiple image quasar RX J0911.4+0551. Dramatic events, such as rapid X-ray flares, are useful in providing...
Emission-Line Eclipse Mapping of Velocity Fields in Dwarf-Nova Accretion Disk (2002)
Makita, Makoto, Mineshige, Shin
We propose a new method, emission-line eclipse mapping, to map the velocity fields of an accretion disk in position space. Quiescent dwarf novae usually exhibit double-peaked emission line profiles...
Does the Slim-Disk Model Correctly Consider Photon-Trapping Effects? (2002)
Ohsuga, Ken, Mineshige, Shin, Mori, Masao, Umemura, Masayuki
We investigate the photon-trapping effects in the super-critical black hole accretion flows by solving radiation transfer as well as the energy equations of radiation and gas. It is found that the...
Can neutrino-cooled accretion disk be an origin of gamma-ray bursts? (2002)
Kohri, Kazunori, Mineshige, Shin
It is often considered that a massive torus with solar mass or so surrounding a stellar-mass black hole may be a central engine of a gamma-ray burst. We study the properties of such massive accretion...
Coexistence of corona and disk in AGN (2002)
Liu, Bibfang, Mineshige, Shin, Meyer-Hofmeister, Emmi, Meyer, Friedrich
Slim Disk: Viscosity Prescriptions and Observational Implications (2001)
Watarai, Ken-ya, Mineshige, Shin
We examine the effects of the different viscosity prescriptions and the magnitude of the viscosity parameter, $\alpha$, on the structure of the slim disk, and discuss the observational implications...
X-Ray Microlensing of Bright Quasars (2001)
Takahashi, Rohta, Yonehara, Atsunori, Mineshige, Shin
We calculated the expected microlens light curves for several accretion-flow models and compared the results to find what aspects of distinct flow structures can be extracted from the microlens light...
Slim Disk Model for Ultra-Luminous X-Ray Sources (2000)
Watarai, Ken-ya, Mizuno, Tsunefumi, Mineshige, Shin
The Ultra Luminous X-ray Sources (ULXs) are unique in exhibiting moderately bright X-ray luminosities, $L_{\rm x} \sim 10^{38-40} {\rm erg~s^{-1}}$, and relatively high blackbody temperatures, $\Tin...
Kawaguchi, Toshihiro, Shimura, Toshiya, Mineshige, Shin
We construct a disk-corona model which accounts for the optical-to-X-ray spectral properties of Seyfert nuclei and QSOs. We study emission spectrum emerging from a vertical disk-corona structure...
Slim Disk Model for Narrow-Line Seyfert 1 Galaxies (2000)
Mineshige, Shin, Takeuchi, Mitsuru
We argue that both the extreme soft X-ray excess and the large-amplitude variability of Narrow-Line Seyfert 1 galaxies (NLS1s) can be explained in the framework of the slim disk model. When the disk...
Slim Disk Model for Soft X-Ray Excess and Variability of Narrow-Line Seyfert 1 Galaxies (2000)
Mineshige, Shin, Kawaguchi, Toshihiro, Takeuchi, Mitsuru, Hayashida, Kiyoshi
Narrow-line Seyfert 1 galaxies (NLS1s) exhibit extreme soft X-ray excess and large variability. We argue that both features can be basically accounted for by the slim disk model. We assume that a...
Evolution of Hydromagnetic Disturbances in Low Ionized Cosmic Plasmas (1999)
Nomura, Hideko, Kamaya, Hideyuki, Mineshige, Shin
We consider the propagation of hydromagnetic waves generated by a compact turbulent source in low ionized plasmas, applying the Lighthill theory. We assume the plasma to be isothermal, and adopt a...
Kim, Soon-Wook, Wheeler, J. Craig, Mineshige, Shin
Some effects of irradiation on time-dependent accretion-disk models for black hole X-ray novae are presented. Two types of irradiation are considered: direct irradiation from the inner hot disk and...
Gravitational Mapping of a Quasar Disk (1999)
Mineshige, Shin, Yonehara, Atsunori
Since the radiation from different portions in the central region of a quasar can be successively amplified during a microlensing event, microlensing light curves provide us with fruitful information...
Radiatively Driven Mass Accretion onto Galactic Nuclei by Circumnuclear Starbursts (1998)
Umemura, Masayuki, Fukue, Jun, Mineshige, Shin
We examine the radiatively driven mass accretion onto galactic nuclei due to the intensive radiation from circumnuclear starbursts. The radiation from a starburst not only contracts an inner gas disk...
An X-Ray Microlensing Test of AU-Scale Accretion Disk Structure in Q2237+0305 (1998)
Yonehara, Atsunori, Mineshige, Shin, Manmoto, Tadahiro, Fukue, Jun, Umemura, Masayuki, Turner, Edwin L.
The innermost regions of quasars can be resolved by a gravitational-lens {\lq}telescope{\rq} on scales down to a few AU. For the purpose, X-ray observations are most preferable, because X-rays...
Evolution of X-Ray Clusters of Galaxies and Shock Heating of Intracluster Medium (1997)
Takizawa, Motokazu, Mineshige, Shin
Evolutions of X-ray clusters of galaxies are studied by N-body (shell model) + mesh code (TVD) simulations on the assumption of spherical symmetry. We consider a density perturbation of $10^{15}...
Self-Similar Collapse of a Self-Gravitating Viscous Disk (1997)
Mineshige, Shin, Umemura, Masayuki
A self-similar solution for time evolution of isothermal, self-gravitating viscous disks is found under the condition that $\alpha' \equiv \alpha (H/r)$ is constant in space (where $\alpha$ is the...