Achievements & Publications

Luminosity Functions of Lyman Break Galaxies at zåisebox-0.5ex~4 and z\i̊sebox-0.5ex~5 in the Subaru Deep Field

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Yoshida, Makiko,   Shimasaku, Kazuhiro,   Kashikawa, Nobunari,   Ouchi, Masami,   Okamura, Sadanori,   Ajiki, Masaru

We investigate the luminosity functions of Lyman break galaxies (LBGs) at zåisebox-0.5ex~4 and z\i̊sebox-0.5ex~5 based on optical imaging data obtained in the Subaru Deep Field project. Three samples of LBGs in a contiguous area of 875 arcmin$^2$ are constructed. One consists of 3808 LBGs at z\rs̊ebox-0.5ex~4 down to i'=26.85 selected...

Formation of SMBHs and QSO evolution

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Kawakatu, Nozomu,   Anabuki, Naohisa,   Nagao, Tohru,   Umemura, Masayuki,   Nakagawa, Takao,   Mori, Masao

The 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 the mass accretion on to a galactic center through radiation drag...

Imprint of Gravitational Lensing by Population III Stars in Gamma-Ray Burst Light Curves

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Hirose, Y.,   Umemura, M.,   Yonehara, A.,   Sato, J.

We propose a novel method of extracting the imprint of gravitational lensing by Population III stars in the light curves of gamma-ray bursts (GRBs). Significant portions of GRBs can originate in hypernovae of Population III stars and be gravitationally lensed by foreground Population III stars or their remnants. If the...

The End of the Reionization Epoch Probed by Ly\ensuremathα Emitters at z = 6.5 in the Subaru Deep Field

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Kashikawa, Nobunari,   Shimasaku, Kazuhiro,   Malkan, Matthew A.,   Doi, Mamoru,   Matsuda, Yuichi,   Ouchi, Masami

We report an extensive search for Ly\ensuremathα emitters (LAEs) at z=6.5 in the Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck identified eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs at z=6.5. Based on this spectroscopic sample of 17, complemented by a photometric sample of 58...

Cosmological radiative transfer codes comparison project - I. The static density field tests

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Iliev, Ilian T.,   Ciardi, Benedetta,   Alvarez, Marcelo A.,   Maselli, Antonella,   Ferrara, Andrea,   Gnedin, Nickolay Y.

Radiative transfer (RT) 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 their computational cost has come within reach of currently available computational power. Further progress is retarded by the considerable number of...

Secondary Star Formation in a Population III Object

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Susa, Hajime,   Umemura, Masayuki

We explore the possibility of subsequent star formation after a first star forms in a Population III object, by focusing on the radiation-hydrodynamic (RHD) feedback caused by ionizing photons, as well as H$_2$-dissociating photons. For this purpose, we perform three-dimensional RHD simulations in which the radiative transfer of ionizing photons...

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Luminosity Functions of Lyman Break Galaxies at zåisebox-0.5ex~4 and z\i̊sebox-0.5ex~5 in the Subaru Deep Field

Yoshida, Makiko,   Shimasaku, Kazuhiro,   Kashikawa, Nobunari,   Ouchi, Masami,   Okamura, Sadanori,   Ajiki, Masaru

We investigate the luminosity functions of Lyman break galaxies (LBGs) at zåisebox-0.5ex~4 and z\i̊sebox-0.5ex~5 based on optical imaging data obtained in the Subaru Deep Field project. Three samples of LBGs in a contiguous area of 875 arcmin$^2$ are constructed. One consists of 3808 LBGs at z\rs̊ebox-0.5ex~4 down to i'=26.85 selected...

December 2006   The Astrophysical Journal
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Formation of SMBHs and QSO evolution

Kawakatu, Nozomu,   Anabuki, Naohisa,   Nagao, Tohru,   Umemura, Masayuki,   Nakagawa, Takao,   Mori, Masao

The 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 the mass accretion on to a galactic center through radiation drag...

November 2006   New Astronomy Reviews
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Imprint of Gravitational Lensing by Population III Stars in Gamma-Ray Burst Light Curves

Hirose, Y.,   Umemura, M.,   Yonehara, A.,   Sato, J.

We propose a novel method of extracting the imprint of gravitational lensing by Population III stars in the light curves of gamma-ray bursts (GRBs). Significant portions of GRBs can originate in hypernovae of Population III stars and be gravitationally lensed by foreground Population III stars or their remnants. If the...

October 2006   The Astrophysical Journal
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The End of the Reionization Epoch Probed by Ly\ensuremathα Emitters at z = 6.5 in the Subaru Deep Field

Kashikawa, Nobunari,   Shimasaku, Kazuhiro,   Malkan, Matthew A.,   Doi, Mamoru,   Matsuda, Yuichi,   Ouchi, Masami

We report an extensive search for Ly\ensuremathα emitters (LAEs) at z=6.5 in the Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck identified eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs at z=6.5. Based on this spectroscopic sample of 17, complemented by a photometric sample of 58...

September 2006   The Astrophysical Journal
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Cosmological radiative transfer codes comparison project - I. The static density field tests

Iliev, Ilian T.,   Ciardi, Benedetta,   Alvarez, Marcelo A.,   Maselli, Antonella,   Ferrara, Andrea,   Gnedin, Nickolay Y.

Radiative transfer (RT) 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 their computational cost has come within reach of currently available computational power. Further progress is retarded by the considerable number of...

September 2006   Monthly Notices of the Royal Astronomical Society
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Secondary Star Formation in a Population III Object

Susa, Hajime,   Umemura, Masayuki

We explore the possibility of subsequent star formation after a first star forms in a Population III object, by focusing on the radiation-hydrodynamic (RHD) feedback caused by ionizing photons, as well as H$_2$-dissociating photons. For this purpose, we perform three-dimensional RHD simulations in which the radiative transfer of ionizing photons...

July 2006   The Astrophysical Journal Letters