Iwakami, Wakana, Kotake, Kei, Ohnishi, Naofumi, Yamada, Shoichi, Sawada, Keisuke
We studied the effects of rotation on standing accretion shock instability (SASI) by performing three-dimensional hydrodynamics simulations. Taking into account a realistic equation of state and...
Nakazato, Ken'ichiro, Sumiyoshi, Kohsuke, Suzuki, Hideyuki, Yamada, Shoichi
Recently, stellar collapse involving black hole formation from massive stars is suggested to emit enormous fluxes of neutrinos on par with ordinary core-collapse supernovae. We investigate their...
Nagakura, Hiroki, Yamada, Shoichi
We study the stability of standing shock waves in advection-dominated accretion flows into a Schwarzschild black hole by 2D general relativistic hydrodynamic simulations as well as linear analysis in...
Nakazato, Ken'ichiro, Sumiyoshi, Kohsuke, Yamada, Shoichi
We construct an equation of state including the hadron-quark phase transition. The mixed phase is obtained by the Gibbs conditions for finite temperature. We adopt the equation of state based on the...
Iwakami, Wakana, Kotake, Kei, Ohnishi, Naofumi, Yamada, Shoichi, Sawada, Keisuke
We have studied non-axisymmetric standing accretion shock instability, or SASI, by 3D hydrodynamical simulations. This is an extention of our previous study on axisymmetric SASI. We have prepared a...
Sawai, Hidetomo, Kotake, Kei, Yamada, Shoichi
A series of numerical simulations on magnetorotational core-collapse supernovae are carried out. Dipole-like configurations which are offset northward are assumed for the initially strong magnetic...
Nakazato, Ken'ichiro, Sumiyoshi, Kohsuke, Yamada, Shoichi
The existence of various anomalous stars, such as the first stars in the universe or stars produced by stellar mergers, has been recently proposed. Some of these stars will result in black hole...
Yasutake, Nobutoshi, Kotake, Kei, Hashimoto, Masa-aki, Yamada, Shoichi
We perform two-dimensional, magnetohydrodynamical core-collapse simulations of massive stars accompanying the QCD phase transition. We study how the phase transition affects the gravitational...
The g-mode Excitation in the Proto Neutron Star by the Standing Accretion Shock Instability (2007)
Yoshida, Shijun, Ohnishi, Naofumi, Yamada, Shoichi
The so-called "acoustic revival mechanism" of core-collapse supernova proposed recently by the Arizona group is an interesting new possibility. Aiming to understand the elementary processes involved...
Gravitational Radiation from Standing Accretion Shock Instability in Core-Collapse Supernovae (2006)
Kotake, Kei, Ohnishi, Naofumi, Yamada, Shoichi
We present the results of numerical experiments, in which we study how the asphericities induced by the growth of the standing accretion shock instability (SASI) produce the gravitational waveforms...
Stability of the Accretion Flows with Stalled Shocks in Core-Collapse Supernovae (2006)
Yamasaki, Tatsuya, Yamada, Shoichi
Bearing in mind the application to the theory of core-collapse supernovae, we performed a global linear analysis on the stability of spherically symmetric accretion flows through a standing shock...
Standing Accretion Shocks in the Supernova Core: Effects of Convection and Realistic EOS (2006)
Yamasaki, Tatsuya, Yamada, Shoichi
We investigated the structure of the spherically symmetric accretion flows through the standing shock wave onto the proto-neutron star in the post-bounce phase of the collapse-driven supernova. We...
Ohnishi, Naofumi, Kotake, Kei, Yamada, Shoichi
We present the results of numerical experiments, in which we have investigated the influence of the inelastic neutrino-helium interactions on the standing accretion shock instability supposed to...
Magnetohydrodynamic Simulations of A Rotating Massive Star Collapsing to A Black Hole (2006)
Fujimoto, Shin-ichiro, Kotake, Kei, Yamada, Shoichi, Hashimoto, Masa-aki, Sato, Katsuhiko
We perform two-dimensional, axisymmetric, magnetohydrodynamic simulations of the collapse of a rotating star of 40 Msun and in the light of the collapsar model of gamma-ray burst. Considering two...
Heavy element nucleosynthesis in a collapsar (2006)
Fujimoto, Shin-ichirou, Hashimoto, Masa-aki, Kotake, Kei, Yamada, Shoichi
We investigate synthesis of heavy elements in a collapsar. We have calculated detailed composition of magnetically driven jets ejected from a collapsar, which is based on long-term,...
Toward Radiation-Magnetohydrodynamic Simulations in Core-Collapse Supernovae (2005)
Kotake, Kei, Ohnishi, Naofumi, Yamada, Shoichi, Sato, Katsuhiko
We report a current status of our radiation-magnetohydrodynamic code for the study of core-collapse supernovae. In this contribution, we discuss the accuracy of our newly developed numerical code by...
Gravitational Collapse and Neutrino Emission of Population III Massive Stars (2005)
Nakazato, Ken'ichiro, Sumiyoshi, Kohsuke, Yamada, Shoichi
Pop III stars are the first stars in the universe. They do not contain metals and their formation and evolution may be different from that of stars of later generations. In fact, according to the...
Ohnishi, Naofumi, Kotake, Kei, Yamada, Shoichi
We have numerically studied the instability of the spherically symmetric standing accretion shock wave against non-spherical perturbations. We have in mind the application to the collapse-driven...
Effects of Magnetic Fields on Proto-Neutron Star Winds (2005)
Ito, Hirotaka, Yamada, Shoichi, Sumiyoshi, Kohsuke, Nagataki, Shigehiro
We discuss effects of magnetic fields on proto-neutron star winds by performing numerical simulation. We assume that the atmosphere of proto-neutron star has a homogenous magnetic field (ranging from...
The Core-Collapse Supernova with "Non-Uniform" Magnetic Fields (2005)
Sawai, Hidetomo, Kotake, Kei, Yamada, Shoichi
We perform two-dimensional numerical simulations on the core-collapse of a massive star with strong magnetic fields and differential rotations using a numerical code ZEUS-2D. Changing field...
R-Process Nucleosynthesis in MHD Jet Explosions of Core-Collapse Supernovae (2005)
Nishimura, Sunao, Kotake, Kei, Hashimoto, Masa-aki, Yamada, Shoichi, Nishimura, Nobuya, Fujimoto, Shinichiro, ...
We investigate $r$-process nucleosynthesis during the magnetohydrodynamical (MHD) explosion of supernova in a massive star of 13 $M_{\odot}$. Contrary to the case of the spherical explosion, jet-like...
North-South Neutrino Heating Asymmetry in Strongly Magnetized and Rotating Stellar Cores (2004)
Kotake, Kei, Yamada, Shoichi, Sato, Katsuhiko
We perform a series of two-dimensional magnetohydrodynamic simulations of supernova cores. Since the distributions of the angular momentum and the magnetic fields of strongly magnetized stars are...
Hydrodynamical effects in internal shock of relativistic outflows (2004)
Kino, Motoki, Mizuta, Akira, Yamada, Shoichi
We study both analytically and numerically hydrodynamical effects of two colliding shells, the simplified models of the internal shock in various relativistic outflows such as gamma-ray bursts and...
General Relativistic Magnetohydrodynamic Simulations of Collapsars: Rotating Black Hole Cases (2004)
Mizuno, Yosuke, Yamada, Shoichi, Koide, Shinji, Shibata, Kazunari
We have performed 2.5-dimensional general relativistic magnetohydrodynamic (MHD) simulations of collapsars including a rotating black hole. This paper is an extension of our previous paper (Mizuno et...
Propagation and Dynamics of Relativistic Jets (2004)
Mizuta, Akira, Yamada, Shoichi, Takabe, Hideaki
We investigate the dynamics and morphology of jets propagating into the interstellar medium using 2D relativistic hydrodynamic simulations. The calculations are performed assuming axisymmetric...
Kotake, Kei, Yamada, Shoichi, Sato, Katsuhiko, Sumiyoshi, Kohsuke, Ono, Hiroyuki, Suzuki, Hideyuki
We perform a series of two-dimensional, axisymmetric, magnetohydrodynamic simulations of the rotational collapse of a supernova core. In order to calculate the waveforms of the gravitational wave, we...
General Relativistic Magnetohydrodynamic Simulations of Collapsars (2003)
Mizuno, Yosuke, Yamada, Shoichi, Koide, Shinji, Shibata, Kazunari
We have performed 2.5-dimensional general relativistic magnetohydrodynamic (MHD) simulations of the gravitational collapse of a magnetized rotating massive star as a model of gamma ray bursts (GRBs)....
Gravitational Radiation from Axisymmetric Rotational Core Collapse (2003)
Kotake, Kei, Yamada, Shoichi, Sato, Katsuhiko
We have done a series of two-dimensional hydrodynamic simulations of the rotational collapse of a supernova core in axisymmetry. We have employed a realistic equation of state (EOS) and taken into...
Kohri, K., Yamada, Shoichi, Nagataki, S.
We study the equation of state of electron in strong magnetic fields which are greater than the critical value $B_c \simeq 4.4 \times 10^{13}$ Gauss. We find that such a strong magnetic field induces...
Polarization tensors in a strong magnetic field (2001)
The vacuum polarization tensor in strong external magnetic fields has been evaluated numerically for various strengths of magnetic fields and momenta of photons under the threshold of the $e^{\pm}$...
Boltzmann equations for neutrinos with flavor mixings (2000)
With a view of applications to the simulations of supernova explosion and proto neutron star cooling, we derive the Boltzmann equations for the neutrino transport with the flavor mixing based on the...
Reduction of neutrino - nucleon scattering rate by nucleon - nucleon collisions (1999)
We studied possible modifications of the neutrino - nucleon scattering rate due to the nucleon - nucleon collisions in the hot dense matter which we find in the supernova core. We show that the...
Yamada, Shoichi, Toki, Hiroshi
In view of the application to supernova simulations, we calculate neutrino reaction rates with nucleons via the neutral and charged currents in the supernova core in the relativistic random phase...
Yamada, Shoichi, Ohashi, Eiji, Agata, Norio, Venkateswaran, Kasthuri
As 16S rRNA sequence analysis has proven inadequate for the differentiation of Bacillus cereus from closely related species, we employed the gyrase B gene (gyrB) as a molecular diagnostic marker. The...
Neutrino transport in type II supernovae: Boltzmann solver vs. Monte Carlo method (1998)
Shoichi Yamada, Hans-thomas Janka
. We have coded a Boltzmann solver based on a finite difference scheme (S N method) aiming at calculations of neutrino transport in type II supernovae. Close comparison between the Boltzmann solver...
Neutrino transport in type II supernovae: Boltzmann solver vs. Monte Carlo method (1998)
Yamada, Shoichi, Janka, Hans-Thomas, Suzuki, Hideyuki
We have coded a Boltzmann solver based on a finite difference scheme (S_N method) aiming at calculations of neutrino transport in type II supernovae. Close comparison between the Boltzmann solver and...
Explosive Nucleosynthesis in Axisymmetrically Deformed Type II Supernovae (1997)
Nagataki, Shigehiro, Hashimoto, Masa-aki, Sato, Katsuhiko, Yamada, Shoichi
Explosive nucleosynthesis under the axisymmetric explosion in Type II supernova has been performed by means of two dimensional hydrodynamical calculations. We have compared the results with the...
An implicit Lagrangian hydrodynamics code for general relativistic spherical collapse is presented. This scheme is based on an approximate linearized Riemann solver (Roe type scheme). This code is...
Yamada, Shoichi, Ohashi, Eiji, Agata, Norio, Venkateswaran, Kasthuri
As 16S rRNA sequence analysis has proven inadequate for the differentiation of Bacillus cereus from closely related species, we employed the gyrase B gene (gyrB) as a molecular diagnostic marker. The...
Yamada, Shoichi, Ohashi, Eiji, Agata, Norio, Venkateswaran, Kasthuri
As 16S rRNA sequence analysis has proven inadequate for the differentiation of Bacillus cereus from closely related species, we employed the gyrase B gene (gyrB) as a molecular diagnostic marker. The...