Achievements & Publications

An X-ray microlensing test of AU-scale quasar disk structure

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Yonehara, A.,   Mineshige, S.,   Manmoto, T.,   Fukue, J.,   Umemura, M.,   Turner, E.~L.

The innermostregion of quasars can be resolved by microlensing on scales down to a few AU. For this purpose, X-rays originating from the innermost regions can be selectively amplified by microlensing resulting from the ``caustic crossing'' events, and observations at X-ray bands are most preferable. If the observation has been...

Formation of Large-Scale Obscuring Wall and Active Galactic Nucleus Evolution Regulated by Circumnuclear Starbursts

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Ohsuga, Ken,   Umemura, Masayuki

By considering the radiative force by a circumnuclear starburst as well as an active galactic nucleus (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 support a stable gaseous wall with...

Radiation Hydrodynamical Mass Accretion onto Galactic Nuclei Driven by Circumnuclear Starbursts

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Ohsuga, Ken,   Umemura, Masayuki,   Fukue, Jun,   Mineshige, Shin

We explore the radiation hydrodynamical evolution of a galactic nuclear gas disk exposed to intense radiation from circumnuclear starbursts. The evolution is characterized by two stages. First, the disk is radially contracted by the radiation force. Subsequently, the surface stratum of the disk avalanches onto the center due to the...

On the Mass of Population III Stars

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Nakamura, Fumitaka,   Umemura, Masayuki

Performing one-dimensional hydrodynamical calculations coupled with nonequilibrium processes for hydrogen molecule formation, we pursue the thermal and dynamical evolution of filamentary primordial gas clouds and attempt to make an estimate on the mass of Population III stars. The cloud evolution is computed from the central proton density n$_c$åisebox-0.5ex~10$^2$-10$^4$ cm$^-3$ up...

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An X-ray microlensing test of AU-scale quasar disk structure

Yonehara, A.,   Mineshige, S.,   Manmoto, T.,   Fukue, J.,   Umemura, M.,   Turner, E.~L.

The innermostregion of quasars can be resolved by microlensing on scales down to a few AU. For this purpose, X-rays originating from the innermost regions can be selectively amplified by microlensing resulting from the ``caustic crossing'' events, and observations at X-ray bands are most preferable. If the observation has been...

January 2000  
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Formation of Large-Scale Obscuring Wall and Active Galactic Nucleus Evolution Regulated by Circumnuclear Starbursts

Ohsuga, Ken,   Umemura, Masayuki

By considering the radiative force by a circumnuclear starburst as well as an active galactic nucleus (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 support a stable gaseous wall with...

August 1999   The Astrophysical Journal Letters
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Radiation Hydrodynamical Mass Accretion onto Galactic Nuclei Driven by Circumnuclear Starbursts

Ohsuga, Ken,   Umemura, Masayuki,   Fukue, Jun,   Mineshige, Shin

We explore the radiation hydrodynamical evolution of a galactic nuclear gas disk exposed to intense radiation from circumnuclear starbursts. The evolution is characterized by two stages. First, the disk is radially contracted by the radiation force. Subsequently, the surface stratum of the disk avalanches onto the center due to the...

June 1999   Publications of the Astronomical Society of Japan
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On the Mass of Population III Stars

Nakamura, Fumitaka,   Umemura, Masayuki

Performing one-dimensional hydrodynamical calculations coupled with nonequilibrium processes for hydrogen molecule formation, we pursue the thermal and dynamical evolution of filamentary primordial gas clouds and attempt to make an estimate on the mass of Population III stars. The cloud evolution is computed from the central proton density n$_c$åisebox-0.5ex~10$^2$-10$^4$ cm$^-3$ up...

April 1999   The Astrophysical Journal