Formation Criteria and the Mass of Secondary Population III Stars (2009)
Susa, Hajime, Umemura, Masayuki, Hasegawa, Kenji
We 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...
The escape of ionizing photons from supernova-dominated primordial galaxies (2009)
Yajima, Hidenobu, Umemura, Masayuki, Mori, Masao, Nakamoto, Taishi
In order to assess the contribution of Lyman break galaxies (LBGs) and Lyman alpha emitters (LAEs) at redshifts 36.
Cosmological Radiative Transfer Comparison Project II: The Radiation-Hydrodynamic Tests (2009)
Iliev, Ilian T., Whalen, Daniel, Mellema, Garrelt, Ahn, Kyungjin, Baek, Sunghye, Gnedin, Nickolay Y., ...
The development of radiation hydrodynamical methods that are able to follow gas dynamics and radiative transfer self-consistently is key to the solution of many problems in numerical astrophysics....
Formation of globular clusters induced by external ultraviolet radiation (2009)
Hasegawa, Kenji, Umemura, Masayuki, Kitayama, Tetsu
We 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...
Radiative Regulation of Population III Star Formation (2009)
Hasegawa, Kenji, Umemura, Masayuki, Susa, Hajime
We 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...
The Impact of a Supernova Explosion in a Very Massive Binary (2008)
Sato, Jun'ichi, Umemura, Masayuki, Sawada, Keisuke
We 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...
Cosmological radiative transfer codes comparison project - I. The static density field tests (2007)
Iliev, Ilian T., Ciardi, Benedetta, Alvarez, Marcelo A., Maselli, Antonella, Ferrara, Andrea, Gnedin, Nickolay Y., ...
Radiative transfer simulations are now at the forefront of numerical astrophysics. They are becoming crucial for an increasing number of astrophysical and cosmological problems; at the same time...
Type I Ultraluminous Infrared Galaxies: Transition Stage from ULIRGs to QSOs (2007)
Kawakatu, Nozomu, Anabuki, Naohisa, Nagao, Tohru, Umemura, Masayuki, Nakagawa, Takao
We examine whether the ultraluminous infrared galaxies that contain a type I Seyfert nucleus (a type I ULIRG) are in the transition stage from ULIRGs to quasi-stellar objects (QSOs). To inspect this...
Large-Scale Structure of Short-Lived Lyman\alpha Emitters (2007)
Shimizu, Ikkoh, Umemura, Masayuki, Yonehara, Atsunori
Recently 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...
Chemodynamics of Lyman alpha emitters, Lyman break galaxies and elliptical galaxies (2006)
Mori, Masao, Umemura, Masayuki
We 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...
Secondary Star Formation in a Population III Object (2006)
Susa, Hajime, Umemura, Masayuki
We 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...
Cosmological Radiative Transfer Codes Comparison Project I: The Static Density Field Tests (2006)
Iliev, Ilian T., Ciardi, Benedetta, Alvarez, Marcelo A., Maselli, Antonella, Ferrara, Andrea, Gnedin, Nickolay Y., ...
Radiative transfer simulations are now at the forefront of numerical astrophysics. They are becoming crucial for an increasing number of astrophysical and cosmological problems; at the same time...
Cosmological radiative transfer codes comparison project – I. The static density field tests (2006)
Iliev, Ilian T., Ciardi, Benedetta, Alvarez, Marcelo A., Maselli, Antonella, Ferrara, Andrea, Gnedin, Nickolay Y., ...
The evolution of galaxies from primeval irregulars to present-day ellipticals (2005)
Mori, Masao, Umemura, Masayuki
The 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...
Type I ULIRGs: Transition Stage from ULIRGs to QSOs (2005)
Kawakatu, Nozomu, Anabuki, Naohisa, Nagao, Tohru, Umemura, Masayuki, Nakagawa, Takao
We examine whether the ultraluminous infrared galaxies that contain a type I Seyfert nucleus (a type I ULIRG) are in the transition stage from ULIRGs to quasi-stellar objects (QSOs). To inspect this...
Formation of Massive Black Holes in Globular Clusters (2005)
Kawakatu, Nozomu, Umemura, Masayuki
The 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...
QSO Formation under Coevolution of SMBH and Bulge (2005)
Kawakatu, Nozomu, Umemura, Masayuki, Mori, Masao
he 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...
The Formation of Population III Binaries (2004)
Saigo, Kazuya, Matsumoto, Tomoaki, Umemura, Masayuki
We 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...
Obscuration of Active Galactic Nuclei by Circumnuclear Starbursts (2004)
Watabe, Yasuyuki, Umemura, Masayuki
We 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...
The Nature of Lya Blobs: Supernova-Dominated Primordial Galaxies (2004)
Mori, Masao, Umemura, Masayuki, Ferrara, Andrea
We 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...
Gas stripping by radiation drag from an interstellar cloud (2004)
Sato, Jun'ichi, Umemura, Masayuki, Sawada, Keisuke, Matsuyama, Shingo
We 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...
Effects of Early Cosmic Reionization on the Substructure Problem in Galactic Halo (2004)
Susa, Hajime, Umemura, Masayuki
Recent 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...
Involvement of IL-17 in Fas ligand-induced inflammation (2004)
Umemura, Masayuki, Kawabe, Takaya, Shudo, Koyo, Kidoya, Hiroyasu, Fukui, Masayuki, Asano, Masahide, ...
Fas ligand (FasL) has been well characterized as a death factor. However, recent studies revealed that ectopic expression of FasL induces inflammation associated with massive neutrophil infiltration....
Why Massive Black Holes are Small in Disk Galxies? (2003)
Kawakatu, Nozomu, Umemura, Masayuki
A 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....
Quasar Mesolensing - Direct Probe to Substructures around Galaxies - (2003)
Yonehara, Atsunori, Umemura, Masayuki, Susa, Hajime
Recently, ``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...
Formation of Dwarf Galaxies during the Cosmic Reionization (2003)
Susa, Hajime, Umemura, Masayuki
We reanalyze the photoevaporation problem of subgalactic objects irradiated by UVB radiation in a reionized universe. For the purpose, we perform three-dimensional radiation...
The Growth of Supermassive Black Holes and QSO Formation (2003)
A 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...
Fas ligand induces cell-autonomous NF-κB activation and IL-8 production (2003)
Imamura, Ryu, Fukui, Masayuki, Kawabe, Takaya, Umemura, Masayuki, Suda, Takashi
Genomic structure and inducible expression of the IL-22 receptor α chain in mice (2003)
Tachiiri, Akio, Imamura, Ryu, Wang, Yetao, Fukui, Masayuki, Umemura, Masayuki, Suda, Takashi
Cosmic Structure Formation and Dynamics: (2003)
Numerical Simulations Linking, Ryoji Matsumoto, Masao Mori, Masayuki Umemura, Takaaki Yokoyama, Tekehiro Miyagoshi, ...
n emerging twisted flux tube interacts with overlying coronal magnetic fields, strong twist is injected into the open coronal fields by magnetic reconnection. As a result of this process, shear...
A Search for Lyman alpha Emitters at Redshift 3.7 (2002)
Fujita, Shinobu S., Ajiki, Masaru, Shioya, Yasuhiro, Nagao, Tohru, Murayama, Takashi, Taniguchi, Yoshiaki, ...
We present the results of a survey for emission-line objects based on optical intermediate-band ($\lambda_{\rm c}$ = 5736 \AA ~ and $\Delta\lambda$ = 280 \AA) and broad-band ($B$, $V$, $R$, and...
Proto-Quasars:Physical States and Observable Properties (2002)
Kawakatu, Nozomu, Umemura, Masayuki, Mori, Masao
Based 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...
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...
The Stellar Initial Mass Function in Primordial Galaxies (2002)
Nakamura, Fumitaka, Umemura, Masayuki
In 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...
Kawakatu, Nozomu, Umemura, Masayuki
We 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...
As 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...
The Stellar IMF in Very Metal-Deficient Gas (2001)
Nakamura, Fumitaka, Umemura, Masayuki
In 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...
Ohsuga, Ken, Umemura, Masayuki
We 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...
Circumnuclear obscuration of the Circinus galaxy by a starburst-radiation supported wall (2001)
Ohsuga, Ken, Umemura, Masayuki
We 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...
On the Initial Mass Function of Population III Stars (2000)
Nakamura, Fumitaka, Umemura, Masayuki
The 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...
UV Background-Induced Bifurcation of the Galactic Morphology (2000)
Susa, Hajime, Umemura, Masayuki
Based 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...
Formation of Primordial Galaxies under UV background Radiation (2000)
Susa, Hajime, Umemura, Masayuki
The 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...
Ohsuga, Ken, Umemura, Masayuki
By 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...
On the Mass of Population III Stars (1998)
Nakamura, Fumitaka, Umemura, Masayuki
Performing 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...
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...
Tajiri, Yukiko, Umemura, Masayuki
To 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...
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...
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...
Expression of Mouse Mammary Tumor Virus Superantigen Accelerates Tumorigenicity of Myeloma Cells
Umemura, Masayuki, Wajjwalku, Worawidh, Upragarin, Narin, Liu, Tie, Nishimura, Hitoshi, Matsuguchi, Tetsuya, ...
To investigate whether superantigen (SAG) from endogenous mouse mammary tumor virus functions as an immunogenic or a tumorigenic factor in tumor development, the BALB/c myeloma cell line FO was...
Umemura, Masayuki, Nishimura, Hitoshi, Saito, Kimika, Yajima, Toshiki, Matsuzaki, Goro, Mizuno, Satoru, ...
Interleukin-15 (IL-15) transgenic mice which had been inoculated with Mycobacterium bovis bacillus Calmette-Guérin (BCG) 24 weeks previously showed resistance against airborne infection with...
Fas ligand induces cell-autonomous NF-κB activation and IL-8 production
Imamura, Ryu, Fukui, Masayuki, Kawabe, Takaya, Umemura, Masayuki, Suda, Takashi
Genomic structure and inducible expression of the IL-22 receptor α chain in mice
Tachiiri, Akio, Imamura, Ryu, Wang, Yetao, Fukui, Masayuki, Umemura, Masayuki, Suda, Takashi
Expression of Mouse Mammary Tumor Virus Superantigen Accelerates Tumorigenicity of Myeloma Cells
Umemura, Masayuki, Wajjwalku, Worawidh, Upragarin, Narin, Liu, Tie, Nishimura, Hitoshi, Matsuguchi, Tetsuya, ...
To investigate whether superantigen (SAG) from endogenous mouse mammary tumor virus functions as an immunogenic or a tumorigenic factor in tumor development, the BALB/c myeloma cell line FO was...
Umemura, Masayuki, Nishimura, Hitoshi, Saito, Kimika, Yajima, Toshiki, Matsuzaki, Goro, Mizuno, Satoru, ...
Interleukin-15 (IL-15) transgenic mice which had been inoculated with Mycobacterium bovis bacillus Calmette-Guérin (BCG) 24 weeks previously showed resistance against airborne infection with...
Fas ligand induces cell-autonomous NF-κB activation and IL-8 production
Imamura, Ryu, Fukui, Masayuki, Kawabe, Takaya, Umemura, Masayuki, Suda, Takashi
Genomic structure and inducible expression of the IL-22 receptor α chain in mice
Tachiiri, Akio, Imamura, Ryu, Wang, Yetao, Fukui, Masayuki, Umemura, Masayuki, Suda, Takashi
Nishimura, Hitoshi, Yajima, Toshiki, Naiki, Yoshikazu, Tsunobuchi, Hironaka, Umemura, Masayuki, Itano, Keiko, ...
At least two types of interleukin (IL)-15 mRNA isoforms are generated by alternative splicing at the 5′ upstream of exon 5 in mice. To elucidate the potential roles of IL-15 isoforms in immune...
How Massive Are Population Iii Stars?
Fumitaka Nakamura, Masayuki Umemura, Up To, M Fi Pc
Performing one-dimensional hydrodynamical calculations coupled with nonequilibrium processes for hydrogen molecule formation, we pursue the thermal and dynamical evolution of filamentary primordial...
Hamada, Satoru, Umemura, Masayuki, Shiono, Takeru, Hara, Hiromitsu, Kishihara, Kenji, Tanaka, Kensho, ...
Murine γδ T cells participate in the innate immune response against infection by an intracellular pathogen Listeria monocytogenes. Vδ1+γδ T cells coexpressing Vγ6 are a major γδ T-cell...