Achievements & Publications

A Spectrophotometric Method to Determine the Inclination of Class I Objects

Image

Nakazato, Takeshi,   Nakamoto, Taishi,   Umemura, Masayuki

A new method that 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 construct a protostar model by carefully treating...

Protoquasars: Physical States and Observable Properties

Image

Kawakatu, Nozomu,   Umemura, Masayuki,   Mori, Masao

Based on the radiation hydrodynamic model for black hole (BH) growth and incorporating the chemical evolution of the early-type host galaxy, we construct the coevolution model of the quasar (QSO) BH and host galaxy. As a result, it is found that after a galactic wind epoch, the luminosity is shifted...

A Search for Ly\ensuremathα Emitters at Redshift 3.7

Image

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 (\ensuremathłambda$_c$=5736 ̊A and \ensuremathΔ\ensuremathłambda=280 \Å) and broadband (B, V, R, and i') observations of the Subaru/XMM-Newton Deep Field with the 8.2 m Subaru telescope and the Subaru Prime Focus Camera (Suprime-Cam). All the data were obtained...

Does the Slim-Disk Model Correctly Consider Photon-trapping Effects?

Image

Ohsuga, Ken,   Mineshige, Shin,   Mori, Masao,   Umemura, Masayuki

We investigate the photon-trapping effects in the supercritical 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 of the disk around the Eddington luminosity (L$_E$) and is not accurate in...

The Stellar Initial Mass Function in Primordial Galaxies

Image

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 one-dimensional numerical hydrodynamics coupled with nonequilibrium chemistry of H$_2$ and HD. It is found that the cloud evolution is governed mainly by the initial central...

Image

A Spectrophotometric Method to Determine the Inclination of Class I Objects

Nakazato, Takeshi,   Nakamoto, Taishi,   Umemura, Masayuki

A new method that 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 construct a protostar model by carefully treating...

January 2003   The Astrophysical Journal
Image

Protoquasars: Physical States and Observable Properties

Kawakatu, Nozomu,   Umemura, Masayuki,   Mori, Masao

Based on the radiation hydrodynamic model for black hole (BH) growth and incorporating the chemical evolution of the early-type host galaxy, we construct the coevolution model of the quasar (QSO) BH and host galaxy. As a result, it is found that after a galactic wind epoch, the luminosity is shifted...

January 2003   The Astrophysical Journal
Image

A Search for Ly\ensuremathα Emitters at Redshift 3.7

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 (\ensuremathłambda$_c$=5736 ̊A and \ensuremathΔ\ensuremathłambda=280 \Å) and broadband (B, V, R, and i') observations of the Subaru/XMM-Newton Deep Field with the 8.2 m Subaru telescope and the Subaru Prime Focus Camera (Suprime-Cam). All the data were obtained...

January 2003   The Astronomical Journal
Image

Does the Slim-Disk Model Correctly Consider Photon-trapping Effects?

Ohsuga, Ken,   Mineshige, Shin,   Mori, Masao,   Umemura, Masayuki

We investigate the photon-trapping effects in the supercritical 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 of the disk around the Eddington luminosity (L$_E$) and is not accurate in...

July 2002   The Astrophysical Journal
Image

The Stellar Initial Mass Function in Primordial Galaxies

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 one-dimensional numerical hydrodynamics coupled with nonequilibrium chemistry of H$_2$ and HD. It is found that the cloud evolution is governed mainly by the initial central...

April 2002   The Astrophysical Journal