Results for "Kyoji Umemura"

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Construction of a Bilingual Dictionary Intermediated by a Third LanguageOct 24 1994When using a third language to construct a bilingual dictionary, it is necessary to discriminate equivalencies from inappropriate words derived as a result of ambiguity in the third language. We propose a method to treat this by utilizing the structures ... More
Improving Compression Based Dissimilarity Measure for Music Score AnalysisOct 04 2017In this paper, we propose a way to improve the compression based dissimilarity measure, CDM. We propose to use a modified value of the file size, where the original CDM uses an unmodified file size. Our application is a music score analysis. We have chosen ... More
Realizing Half-Diminished Reality from Video Stream of Manipulating ObjectsSep 25 2017When we watch a video, in which human hands manipulate objects, these hands may obscure some parts of those objects. We are willing to make clear how the objects are manipulated by making the image of hands semi-transparent, and showing the complete images ... More
Journal Name Extraction from Japanese Scientific News ArticlesJun 11 2019In Japanese scientific news articles, although the research results are described clearly, the article's sources tend to be uncited. This makes it difficult for readers to know the details of the research. In this paper, we address the task of extracting ... More
Analysis of Home Location Estimation with Iteration on Twitter Following RelationshipAug 30 2016User's home locations are used by numerous social media applications, such as social media analysis. However, since the user's home location is not generally open to the public, many researchers have been attempting to develop a more accurate home location ... More
When Do Users Change Their Profile Information on Twitter?Nov 25 2017We can see profile information such as name, description and location in order to know the user on social media. However, this profile information is not always fixed. If there is a change in the user's life, the profile information will be changed. In ... More
Eta-product $η(7τ)^7/η(τ)$Feb 17 2006The Dirichlet series associated to the eta-product $\eta(7\tau)^7/\eta(\tau)$ decomposes uniquely into the difference of two L-functions with Euler products. This expression gives a new proof of the positivity of the Fourier coefficients of the eta-product. ... More
The Zero Locus of the $F$-triangleAug 08 2016Aug 13 2016We are interested in the zero locus of a Chapoton's $F$-triangle as a polynomial in two real variables $x$ and $y$. An expectation is that (1) the $F$-triangle of rank $l$ as a polynomial in $x$ for each fixed $y\in[0,1]$, has exactly $l$ distinct real ... More
Growth partition functions for cancellative infinite monoidsSep 30 2010Oct 07 2010We introduce the {\it growth partition function} $Z_{\Gamma,G}(t)$ associate with any cancellative infinite monoid $\Gamma$ with a finite generator system $G$. It is a power series in $t$ whose coefficients lie in integral Lie-like space $\mathcal{L}_{\Z}(\Gamma,G)$ ... More
Limit elements in the configuration algebra for a cancellative monoidJan 31 2012We introduce two spaces $\Omega(\Gamma,G)$ and $\Omega(P_{\Gamma,G})$ of pre-partition functions and of opposite series, respectively, which are associated with a Cayley graph $(\Gamma,G)$ of a cancellative monoid $\Gamma$ with a finite generating system ... More
Coxeter elements for vanishing cycles of type $A_{1/2\infty}$ and $D_{1/2\infty}$Jan 27 2012We introduce two entire functions $f_{A_{1/2\infty}}$and $f_{D_{1/2\infty}}$ in two variables. Both of them have only two critical values 0 and 1, and the associated maps $\C^2 to \C$ define topologically locally trivial fibrations over $\C\setminus{0,1\}$. ... More
Coherence of direct images of the De Rham complexFeb 17 2015Sep 22 2016We show the coherence of the direct images of the De Rham complex relative to a flat holomorphic map with suitable boundary conditions. For this purpose, a notion of bi-dg-algbera called the Koszul-De Rham algbera is dveloped.
Opposite power seriesJan 27 2012Let $\gamma_n$ ($n\in \mathbb{Z}_{\ge0}$) be a sequence of complex numbers, which is tame: $0<\exists u\le \gamma_{n-1}/\gamma_n \le \exists v<\infty$ for all $n>0$. We show a resonance between the singularities of the function of the power series $P(t):=\sum_{n=0}^\infty ... More
Inversion formula for the growth function of a cancellative monoidJan 26 2012Feb 24 2012We consider any cancellative monoid $M$ equipped with a discrete degree map $deg:M\to R_{\ge0}$ and associated generating function $P(t)=\sum_{m\in M}t^{deg(m)}$, called the growth function of $M$. We also introduce, using some towers of minimal common ... More
Principal $Γ$-cone for a treeOct 28 2005Oct 30 2005Each orientation on a Dynkin graph $\Gamma$ defines a cone (in a certain real configuration space) which is further divided into chambers. We enumerate the number of chambers for two particular cones, which are called the pricipal $\Gamma$-cones and are ... More
Analysis of the Influence of Internet TV Station on Wikipedia Page ViewsMar 05 2019We aim to investigate the influence of television on the web; if the influence is strong, a viral effect may be expected. In this paper, we focus on the Internet TV station and on Wikipedia use as exploratory behavior on the web. We analyzed the influence ... More
Analysis of User Dwell Time on Non-News PagesMar 01 2019There is dwell time as one of the indicators of user's behavior, and this indicates how long a user looked at a page. Dwell time is especially useful in fields where user ratings are important, such as search engines, recommender systems, and advertisements ... More
Home Location Estimation Using Weather Observation DataSep 03 2017We can extract useful information from social media data by adding the user's home location. However, since the user's home location is generally not publicly available, many researchers have been attempting to develop a more accurate home location estimation. ... More
Response Collector: A Video Learning System for Flipped ClassroomsAug 22 2018The flipped classroom has become famous as an effective educational method that flips the purpose of classroom study and homework. In this paper, we propose a video learning system for flipped classrooms, called Response Collector, which enables students ... More
Computing Information Quantity as Similarity Measure for Music Classification TaskApr 16 2018This paper proposes a novel method that can replace compression-based dissimilarity measure (CDM) in composer estimation task. The main features of the proposed method are clarity and scalability. First, since the proposed method is formalized by the ... More
Finding Association Rules by Direct Estimation of Likelihood RatiosSep 25 2017In this paper, we propose a cost function that corresponds to the mean square errors between estimated values and true values of conditional probability in a discrete distribution. We then obtain the values that minimize the cost function. This minimization ... More
Confidence Interval of Probability Estimator of Laplace SmoothingSep 25 2017Sometimes, we do not use a maximum likelihood estimator of a probability but it's a smoothed estimator in order to cope with the zero frequency problem. This is often the case when we use the Naive Bayes classifier. Laplace smoothing is a popular choice ... More
Using Conservative Estimation for Conditional Probability instead of Ignoring Infrequent CaseSep 25 2017There are several estimators of conditional probability from observed frequencies of features. In this paper, we propose using the lower limit of confidence interval on posterior distribution determined by the observed frequencies to ascertain conditional ... More
Three-Mirror Anastigmat Telescope with an Unvignetted Flat Focal PlaneApr 23 2005A new optical design concept of telescopes to provide an aberration-free, wide field, unvignetted flat focal plane is described. The system employs three aspheric mirrors to remove aberrations, and provides a semi-circular field of view with minimum vignetting. ... More
Monoids in the fundamental groups of the complement of logarithmic free divisors in C^3Nov 17 2009We study monoids generated by Zariski-van Kampen generators in the 17 fundamental groups of the complement of logarithmic free divisors in C^3 listed by Sekiguchi (Theorem 1). Five of them are Artin monoids and eight of them are free abelian monoids. ... More
The Growth of Supermassive Black Holes and QSO FormationApr 10 2003A novel mechanism to build up a supermassive black hole (SMBH) is proposed. Here, relativistic radiation-hydrodynamic processes are considered from a galactic scale to a horizon scale. In the present scenario, the mass of a SMBH is predicted to be in ... More
Zero loci of skew-growth functions for dual Artin monoidsMar 15 2016Mar 16 2016We show that the skew-growth function of a dual Artin monoid of finite type P has exactly rank(P) =: l simple real zeros on the interval (0, 1]. The proofs for types A_l and B_l are based on an unexpected fact that the skew-growth functions, up to a trivial ... More
A Radiation-Hydrodynamical Model for Supermassive Black Hole-to-Bulge Mass Relation and Quasar FormationAug 30 2001As a potential mechanism to build up supermassive black holes (BHs) in a spheroidal system, we consider the radiation drag effect by bulge stars, which extracts angular momentum from interstellar gas and thus allows the gas to accrete onto the galactic ... More
Polysemy Detection in Distributed Representation of Word SenseSep 26 2017In this paper, we propose a statistical test to determine whether a given word is used as a polysemic word or not. The statistic of the word in this test roughly corresponds to the fluctuation in the senses of the neighboring words a nd the word itself. ... More
A Criterion for Photoionization of Pregalactic Clouds Exposed to Diffuse Ultraviolet Background RadiationJun 03 1998To elucidate the permeation of cosmic ultraviolet (UV) background radiation into a pregalactic cloud and subsequent ionization, the frequency-dependent radiative transfer equation is solved, coupled with the ionization process. A spherical top-hat cloud ... More
The Stellar IMF in Very Metal-Deficient GasJun 01 2001In the context of the star formation through the fragmentation of an extremely metal-deficient protogalactic cloud, the gravitational collapse of filamentary gas clouds is explored with H$_2$ and HD chemistry. It is found by 1D hydrodynamical simulations ... More
On the Initial Mass Function of Population III StarsOct 23 2000The collapse and fragmentation of filamentary primordial gas clouds are explored using 1D and 2D hydrodynamical simulations coupled with the nonequilibrium processes of H2 formation. The simulations show that depending upon the initial density,there are ... More
Self-Similar Collapse of a Self-Gravitating Viscous DiskJan 24 1997A 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 viscosity parameter and $H/r$ is the ratio of a half-thickness ... More
Formation of Dwarf Galaxies during the Cosmic ReionizationSep 06 2003We reanalyze the photoevaporation problem of subgalactic objects irradiated by UVB radiation in a reionized universe. For the purpose, we perform three-dimensional radiation smoothed-particle-hydrodynamics calculations, where the radiative transfer is ... More
Successive Merger of Multiple Massive Black Holes in a Primordial GalaxyJan 12 2011Jan 19 2011Using highly-accurate $N$-body simulations, we explore the evolution of multiple massive black holes (hereafter, MBHs) in a primordial galaxy that is composed of stars and MBHs. The evolution is pursed with a fourth-order Hermite scheme, where not only ... More
Chemodynamics of Lyman alpha emitters, Lyman break galaxies and elliptical galaxiesNov 09 2006We report an ultra-high-resolution simulation that follows evolution from the earliest stages of galaxy formation through the period of dynamical relaxation. The bubble structures of gas revealed in our simulation ($< 3\times 10^8$ years) resemble closely ... More
Obscuration of Active Galactic Nuclei by Circumnuclear StarburstsSep 19 2004We examine the possibility of the active galactic nucleus (AGN) obscuration by dusty gas clouds that spurt out from circumnuclear starburst regions. For the purpose, the dynamical evolution of gas clouds is pursued, including the effects of radiation ... More
On the Mass of Population III StarsDec 21 1998Performing 1D hydrodynamical calculations coupled with non-equilibrium processes for H2 formation, we pursue the thermal and dynamical evolution of filamentary primordial clouds and attempt to make an estimate on the mass of population III stars. It is ... More
Formation of Primordial Galaxies under UV background RadiationJan 11 2000The pancake collapse of pregalactic clouds under UV background radiation is explored with a one-dimensional sheet model. Here, attention is concentrated on elucidating the basic physics on the thermal evolution of pregalactic clouds exposed to diffuse ... More
The evolution of galaxies from primeval irregulars to present-day ellipticalsDec 15 2005Dec 02 2007The current understanding of galaxy formation is that it proceeds in a 'bottom up' way, with the formation of small clumps of gas and stars that merge hierarchically until giant galaxies are built up. The baryonic gas loses the thermal energy by radiative ... More
Radiation drag driven mass accretion in clumpy interstellar medium: implications for the supermassive black hole-to-bulge relationNov 22 2001We quantitatively scrutinize the effects of the radiation drag arising from the radiation fields in a galactic bulge in order to examine the possibility that the radiation drag could be an effective mechanism to extract angular momentum in a spheroidal ... More
Two types of Lyman-alpha emitters envisaged from hierarchical galaxy formationApr 06 2010From multi-wavelength observations of LAEs,we know that while many LAEs appear to be young and less massive,a noticeable fraction of LAEs possess much older populations of stars and larger stellar mass.How these two classes of LAEs are concordant with ... More
GOTHIC: Gravitational oct-tree code accelerated by hierarchical time step controllingOct 24 2016The tree method is a widely implemented algorithm for collisionless $N$-body simulations in astrophysics well suited for GPU(s). Adopting hierarchical time stepping can accelerate $N$-body simulations; however, it is infrequently implemented and its potential ... More
Why Massive Black Holes are Small in Disk Galxies?Dec 08 2003A potential mechanism is proposed to account for the fact that supermassive black holes (SMBHs) in disk galaxies appear to be smaller than those in elliptical galaxies in the same luminosity range. We consider the formation of SMBHs by radiation drag ... More
The Stellar Initial Mass Function in Primordial GalaxiesJan 30 2002In the context of star formation through fragmentation of an extremely metal-deficient protogalactic cloud, the gravitational collapse of filamentary gas clouds is explored with 1D numerical hydrodynamics coupled with non-equilibrium chemistry of H$_2$ ... More
Circumnuclear obscuration of the Circinus galaxy by a starburst-radiation supported wallMay 16 2001We consider the radiation-hydrodynamical formation of a dusty wall in the circumnuclear regions of the Circinus Seyfert 2 galaxy. We focus on the radiative flux force due to the circumnuclear starburst, the nuclear starburst and the active galactic nucleus ... More
Formation of Obscuring Walls by Radiation Force from Circumnuclear Starbursts and Implications for Starburst-Active Galactic Nucleus ConnectionMay 28 2001We explore the formation of dusty gas walls induced by a circumnuclear starburst around an AGN. We concentrate our attention on the role of the radiation force by a starburst as well as an AGN, where the effects of optical depth of dusty gas are taken ... More
Effects of Early Cosmic Reionization on the Substructure Problem in Galactic HaloJun 12 2004Recent observations on the cosmic microwave background by Wilkinson Microwave Anisotropy Probe(WMAP) strongly suggest that the reionization of the universe took place quite early (z \sim 17). On the other hand, it has been pointed out that the cold dark ... More
START: Smoothed particle hydrodynamics with tree-based accelerated radiative transferMay 28 2010We present a novel radiation hydrodynamics code, START, which is a smoothed particle hydrodynamics (SPH) scheme coupled with accelerated radiative transfer. The basic idea for the acceleration of radiative transfer is parallel to the tree algorithm that ... More
Subparsec-scale dynamics of a dusty gas disk exposed to anisotropic AGN radiation with frequency-dependent radiative transferApr 12 2016We explore the gas dynamics near the dust sublimation radius of active galactic nucleus (AGN). For the purpose, we perform axisymmetric radiation hydrodynamic simulations of a dusty gas disk of radius $\approx 1\,\mathrm{pc}$ around a supermassive black ... More
Quantization of Galois theory, Examples and ObservationsDec 14 2012If we consider a q-analogue of linear differential equation, Galoois group of the q-analogue difference equation is still a linear algebraic group. Namely, by a quantization of linear differential equation, Galois group is not quantized. We show by Examples ... More
Formation of Massive Black Holes in Globular ClustersApr 08 2005The hydrodynamic formation of massive black holes (BHs) in globular clusters is considered. In particular, we examine the possibility of the BH formation induced by the radiation drag that is exerted on the interstellar matter by stellar radiation in ... More
Merger Criteria of Multiple Massive Black Holes and the Impact on the Host GalaxyFeb 25 2014We perform N-body simulations on a multiple massive black hole (MBH) system in a host galaxy to derive the criteria for successive MBH merger. The calculations incorporate the dynamical friction by stars and general relativistic effects as pericentre ... More
Formation of Large-Scale Obscuring Wall and AGN Evolution Regulated by Circumnuclear StarburstsJun 14 1999Jun 15 1999By considering the radiative force by a circumnuclear starburst as well as an AGN, we analyze the equilibrium configuration and the stability of dusty gas in the circumnuclear regions. It is found that the radiative force by an intensive starburst can ... More
Secondary Star Formation in a Population III ObjectApr 20 2006We explore the possibility of subsequent star formation after a first star forms in a Pop III object, by focusing on the radiation hydrodynamic (RHD) feedback brought by ionizing photons as well as H2 dissociating photons. For the purpose, we perform ... More
UV Background-Induced Bifurcation of the Galactic MorphologyJun 01 2000Based upon a novel paradigm of the galaxy formation under UV background, the evolutionary bifurcation of pregalactic clouds is confronted with observations on elliptical and spiral galaxies. The theory predicts that the dichotomy between the dissipational ... More
Triangulated categories of matrix factorizations for regular systems of weights with $ε=-1$Aug 01 2007We construct a full strongly exceptional collection in the triangulated category of graded matrix factorizations of a polynomial associated to a non-degenerate regular system of weights whose smallest exponents are equal to -1. In the associated Grothendieck ... More
Painlevé equations and deformations of rational surfaces with rational double pointsJul 26 2000In this paper, we show that the B\"acklund transformations of Painlev\'e equations come from birational maps of rational surfaces constructed by Okamoto as the spaces of initial conditions. The simultaneous resolutions of rational double points of the ... More
Primitive forms via polyvector fieldsNov 07 2013Feb 03 2014We develop a complex differential geometric approach to the theory of higher residues and primitive forms from the viewpoint of Kodaira-Spencer gauge theory, unifying the semi-infinite period maps for Calabi-Yau models and Landau-Ginzburg models. We give ... More
Matrix Factorizations and Representations of Quivers II: type ADE caseNov 07 2005Apr 03 2006We study a triangulated category of graded matrix factorizations for a polynomial of type ADE. We show that it is equivalent to the derived category of finitely generated modules over the path algebra of the corresponding Dynkin quiver. Also, we discuss ... More
Coherence of direct images of the De Rham complexFeb 17 2015Nov 30 2016We show the coherence of the direct images of the De Rham complex relative to a flat holomorphic map with suitable boundary conditions. For this purpose, a notion of bi-dg-algbera called the Koszul-De Rham algbera is dveloped.
From primitive form to mirror symmetryAug 19 2014Aug 22 2014This is a report on the recent work "Mirror symmetry for exceptional unimodular singularities" joint with Changzheng Li, Si Li and Yefeng Shen.
A Spectrophotometric Method to Determine the Inclination of Class I ObjectsOct 11 2002A new method which enables us to estimate the inclination of Class I young stellar objects is proposed. Since Class I objects are not spherically symmetric, it is likely that the observed feature is sensitive to the inclination of the system. Thus, we ... More
Large-Scale Structure of Short-Lived LymanαEmittersJun 12 2007Recently discovered large-scale structure of Ly\alpha Emitters (LAEs) raises a novel challenge to the cold dark matter (CDM) cosmology. The structure is extended over more than 50 Mpc at redshift z=3.1, and exhibits a considerably weak angular correlation. ... More
Finite-Temperature Phase Structure of Lattice QCD with Wilson Quark ActionAug 07 1995Aug 22 1995The long-standing issue of the nature of the critical line of lattice QCD with the Wilson quark action at finite-temperatures, defined to be the line of vanishing pion screening mass, and its relation to the line of finite-temperature chiral tansition ... More
Radiative Regulation of Population III Star FormationFeb 16 2009We explore the impact of ultraviolet (UV) radiation from massive Population III (Pop III) stars of 25, 40, 80, and 120 M_sun on the subsequent Pop III star formation. In this paper, particular attention is paid to the dependence of radiative feedback ... More
Direct Integration of the Collisionless Boltzmann Equation in Six-dimensional Phase Space: Self-gravitating SystemsJun 27 2012We present a scheme for numerical simulations of collisionless self-gravitating systems which directly integrates the Vlasov--Poisson equations in six-dimensional phase space. By the results from a suite of large-scale numerical simulations, we demonstrate ... More
QSO Formation under Coevolution of SMBH and BulgeApr 08 2005he formation and growth of supermassive black holes (SMBHs) physically linked with bulges are considered. We focus on the radiation hydrodynamic process for the growth of SMBH in the optically thick starburst phase, where radiation from bulge stars drives ... More
Radiatively Driven Mass Accretion onto Galactic Nuclei by Circumnuclear StarburstsJun 02 1998We 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 by the radiation flux force, but also extracts angular ... More
Reionization of an Inhomogeneous UniverseAug 10 2001Full radiative transfer in 3D space has been solved to pursue the reionization history in an inhomogeneous universe. It has been shown that the reionization of an inhomogeneous universe is not a prompt event, but a fairly slow process. Also, QSO absorption ... More
Cosmic Reionization and Galaxy FormationAug 10 2001Using 3D radiative transfer calculations on the reionization of an inhomogeneous universe, QSO absorption line systems are simulated and they are compared with observations of Ly$\alpha$ continuum depression at high redshifts. By this comparison, it is ... More
Formation Criteria and the Mass of Secondary Population III StarsJul 11 2009We explore the formation of secondary Population III (Pop III) stars under radiation hydrodynamic (RHD) feedback by a preformed massive star. To properly treat RHD feedback, we perform three-dimensional RHD simulations incorporating the radiative transfer ... More
Formation of globular clusters induced by external ultraviolet radiationMay 14 2009Jul 07 2009We present a novel scenario for globular cluster (GC) formation, where the ultraviolet (UV) background radiation effectively works so as to produce compact star clusters. Here, we explore the formation of GCs in UV radiation fields. For this purpose, ... More
Sub-millimeter brightness of early star-forming galaxiesNov 29 2011Based on a three-dimensional model of an early star-forming galaxy, we explore the evolution of the sub-millimeter brightness. The model galaxy is employed from an ultra-high-resolution chemodynamic simulation of a primordial galaxy by Mori & Umemura, ... More
Fate of the Critical Line and Chiral Transition in Finite-Temperature Lattice QCD with the Wilson Quark ActionOct 06 1995Finite-temperature phase structure of lattice QCD with the Wilson quark action is analyzed. We show that the critical line at finite temperatures, defined to be the line of vanishing pion screening mass, turns back toward strong coupling, forming a cusp ... More
The Formation of Population III BinariesOct 29 2004We explore the possibility for the formation of Population III binaries. The collapse of a rotating cylinder is simulated with a three-dimensional, high-resolution nested grid, assuming the thermal history of primordial gas. The simulations are done with ... More
Three-dimensional Radiative Properties of Hot Accretion Flows onto the Galactic Centre Black HoleJun 24 2009By solving radiative transfer equations, we examine three-dimensional radiative properties of a magnetohydrodynamic accretion flow model confronting with the observed spectrum of Sgr A*, in the vicinity of supermassive black hole at the Galactic centre. ... More
Formation of globular clusters induced by external ultraviolet radiation II: Three-dimensional radiation hydrodynamics simulationsSep 08 2016We explore the possibility of the formation of globular clusters under ultraviolet (UV) background radiation. One-dimensional spherical symmetric radiation hydrodynamics (RHD) simulations by Hasegawa et al. have demonstrated that the collapse of low-mass ... More
The skew-growth function on the monoid of square matricesAug 18 2012Nov 08 2013We develop an elementary theory of divisibility on the monoid $M(n,R)^\times$ consisting of all square matrices of size $n\ge 1$ of non-zero determinants with coefficients in a principal ideal domain $R$. In particular, we show that any finite subset ... More
Mirror symmetry for exceptional unimodular singularitiesMay 18 2014Dec 18 2014In this paper, we prove the mirror symmetry conjecture between the Saito-Givental theory of exceptional unimodular singularities on Landau-Ginzburg B-side and the Fan-Jarvis-Ruan-Witten theory of their mirror partners on Landau-Ginzburg A-side. On the ... More
The Impact of a Supernova Explosion in a Very Massive BinaryApr 21 2008We consider the effect of a supernova (SN) explosion in a very massive binary that is expected to form in a portion of Population III stars with the mass higher than 100$M_\odot$. In a Population III binary system, a more massive star can result in the ... More
The Nature of Lya Blobs: Supernova-Dominated Primordial GalaxiesAug 23 2004Aug 25 2004We consider a forming galaxy undergoing multitudinous supernova (SN) explosions, as a possible model of \lya blobs (LABs). For this purpose, an ultra--high resolution hydrodynamic simulation is performed using $1024^3$ grid points, where SN remnants are ... More
Early Cosmic Formation of Massive Black HolesMar 09 1993The evolution of nonlinear density fluctuations around the Jeans mass shortly after cosmological recombination is analyzed using a 3D hydrodynamics/dark--matter code. The Cosmic Background Radiation (CBR) exerts Compton friction on free electrons due ... More
Proto-Quasars:Physical States and Observable PropertiesSep 22 2002Based on the radiation hydrodynamical model for the black hole(BH) growth,incorporated with the chemical evolution of the early-type host galaxy, we construct the coevolution model of a QSO BH and the host galaxy. As a result, it is found that after a ... More
Quasar Mesolensing - Direct Probe to Substructures around Galaxies -Oct 10 2003Recently, ``CDM crisis'' is under discussion. The main point of this crisis is that number of substructures presented by cosmological N-body simulations based on CDM scenario for structure formation is much larger than observed substructures. Therefore, ... More
Mergers of accreting stellar-mass black holesFeb 28 2016Jul 28 2016We present post-Newtonian $N$-body simulations on mergers of accreting stellar-mass black holes (BHs), where such general relativistic effects as the pericenter shift and gravitational wave (GW) emission are taken into consideration. The attention is ... More
On the evolution of gas clouds exposed to AGN radiation. I. Three-dimensional radiation hydrodynamic simulationsJun 25 2014We perform three-dimensional radiation hydrodynamic simulations of uniform dusty gas clouds irradiated by an active galactic nucleus (AGN) to investigate the dependence of evolution of clouds on the ionization parameter $\mathcal{U}$ and the Str{\"o}mgren ... More
ARGOT: Accelerated radiative transfer on grids using oct-treeMay 17 2011Sep 08 2011We present two types of numerical prescriptions that accelerate the radiative transfer calculation around point sources within a three-dimensional Cartesian grid by using the oct-tree structure for the distribution of radiation sources. In one prescription, ... More
Toward quantization of Galois theoryJan 27 2015Sep 27 2016This note is a development of our two previous papers, arXiv:1212.3392v1 and 1306.3660v1. The fundamental question is whether there exists a Galois theory, in which the Galois group is a quantum group. For a linear equations with respect to a Hopf algebra, ... More
Optical Variability in Active Galactic Nuclei: Starbursts or Disk Instabilities?Nov 30 1997Apr 13 1998Aperiodic optical variability is a common property of Active Galactic Nuclei (AGNs), though its physical origin is still open to question. To study the origin of the optical -- ultraviolet variability in AGN, we compare light curves of two models to observations ... More
Formation and Radiative Feedback of First Objects and First GalaxiesOct 29 2012First, the formation of first objects driven by dark matter is revisited by high-resolution hydrodynamic simulations. It is revealed that dark matter haloes of ~10^4M_sun can produce first luminous objects with the aid of dark matter cusps. Therefore, ... More
Gas stripping by radiation drag from an interstellar cloudJul 13 2004We perform two-dimensional hydrodynamic simulation on the gas stripping by radiation drag from an interstellar cloud moving in uniform radiation fields. To properly include relativistic radiation drag, the radiation hydrodynamic equation is solved with ... More
Finite-Temperature Phase Structure of Lattice QCD with the Wilson Quark Action for Two and Four FlavorsDec 14 1996We present further analyses of the finite-temperature phase structure of lattice QCD with the Wilson quark action based on spontaneous breakdown of parity-flavor symmetry. Results are reported on (i) an explicit demonstration of spontaneous breakdown ... More
Dust Coagulation Regulated by Turbulent Clustering in Protoplanetary DisksJan 26 2018The coagulation of dust particles is a key process in planetesimal formation. However, the radial drift and bouncing barriers are not completely resolved, especially for silicate dust. Since the collision velocities of dust particles are regulated by ... More
Does the Slim-Disk Model Correctly Consider Photon-Trapping Effects?Mar 25 2002We 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 slim-disk model generally overestimates the luminosity ... More
Ultra Fast Outflows: Galaxy-Scale Active Galactic Nucleus FeedbackNov 26 2012Jan 01 2013We show, using global 3D grid-based hydrodynamical simulations, that Ultra Fast Outflows (UFOs) from Active Galactic Nuclei (AGN) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind ... More
Neutron electric dipole moment in a supersymmetric model with singlet quarksDec 18 1995The neutron electric dipole moment is investigated in a supersymmetric electroweak model admitting $ {\rm SU(2)}_W $ singlet and $ Q = -1/3 $, say $ D $-type, quarks. Significant $ CP $ violating phases appear in the coupling between the singlet $ D $-type ... More
The Structure and Evolution of Early Cosmological HII RegionsJun 11 2004We study the formation and evolution of HII regions around the first stars formed at z=10-30. We use a one-dimensional Lagrangian hydrodynamics code which self-consistently incorporates radiative transfer and non-equilibrium primordial gas chemistry. ... More
Driving Outflows with Relativistic Jets and the Dependence of AGN Feedback Efficiency on ISM InhomogeneityMay 02 2012Aug 10 2012We examine the detailed physics of the feedback mechanism by relativistic AGN jets interacting with a two-phase fractal interstellar medium in the kpc-scale core of galaxies using 29 3D grid-based hydrodynamical simulations. The feedback efficiency, as ... More
Imprint of Gravitational Lensing by Population III Stars in Gamma Ray Burst Light CurvesMay 22 2006Oct 24 2006We propose a novel method to extract the imprint of gravitational lensing by Pop III stars in the light curves of Gamma Ray Bursts (GRBs). Significant portions of GRBs can originate in hypernovae of Pop III stars and be gravitationally lensed by foreground ... More