Achievements & Publications

Modeling Nonlinear Evolution of Baryon Acoustic Oscillations: Convergence Regime of N-body Simulations and Analytic Models

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Nishimichi, Takahiro,   Shirata, Akihito,   Taruya, Atsushi,   Yahata, Kazuhiro,   Saito, Shun,   Suto, Yasushi

We used a series of cosmological N-body simulations and various analytic models to study the evolution of the matter power spectrum in real space in a \ensuremathŁambda cold dark matter universe. We compared the results of N-body simulations against three analytical model predictions; standard perturbation theory, renormalized perturbation theory, and...

Kinematic and Chemical Constraints on the Formation of M31's Inner and Outer Halo

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Koch, Andreas,   Rich, R. Michael,   Reitzel, David B.,   Martin, Nicolas F.,   Ibata, Rodrigo A.,   Chapman, Scott C.

The halo of M31 shows a wealth of substructures, some of which are consistent with assembly from satellite accretion. Here we report on kinematic and abundance results from Keck DEIMOS spectroscopy in the near-infrared calcium triplet region of over 3500 red giant star candidates along the minor axis and in...

Suzaku broad-band spectroscopy of RX J1347.5-1145: constraints on the extremely hot gas and non-thermal emission

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Ota, N.,   Murase, K.,   Kitayama, T.,   Komatsu, E.,   Hattori, M.,   Matsuo, H.

Context: We present the results of our analysis of long Suzaku observations (149 ks and 122 ks for XIS and HXD, respectively) of the most X-ray luminous galaxy cluster, RX J1347.5-1145, at z=0.451. Aims: To understand the gas physics of a violent, cluster merger, we study physical properties of the...

Non-Equilibrium Ionization State and Two-Temperature Structure in the Linked Region of Abell 399 and Abell 401

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Akahori, Takuya,   Yoshikawa, Kohji

We investigate a non-equilibrium ionization state and a two-temperature structure of the intracluster medium in the linked region of Abell 399 and Abell 401, using a series of N-body + Smoothed Particle Hydrodynamics (SPH) simulations, and find that there exist significant shock layers at the edge of the linked region...

The impact of a supernova explosion in a very massive binary

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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 100M$_solar$. In a Population III binary system, a more massive star can result in the formation of a black...

Nuclear/Circumnuclear Starbursts and Active Galactic Nucleus Mass Accretion in Seyfert Galaxies

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Watabe, Yasuyuki,   Kawakatu, Nozomu,   Imanishi, Masatoshi

We investigated the correlation between nuclear/circumnuclear starbursts around active galactic nuclei (AGNs) and the AGN activities for 43 Seyfert galaxies in the CfA and 12 \ensuremathμm samples. We found that the circumnuclear starburst luminosity, as well as the nuclear starburst luminosity, is positively correlated with the AGN luminosity. Moreover, the...

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Modeling Nonlinear Evolution of Baryon Acoustic Oscillations: Convergence Regime of N-body Simulations and Analytic Models

Nishimichi, Takahiro,   Shirata, Akihito,   Taruya, Atsushi,   Yahata, Kazuhiro,   Saito, Shun,   Suto, Yasushi

We used a series of cosmological N-body simulations and various analytic models to study the evolution of the matter power spectrum in real space in a \ensuremathŁambda cold dark matter universe. We compared the results of N-body simulations against three analytical model predictions; standard perturbation theory, renormalized perturbation theory, and...

February 2009   Publications of the Astronomical Society of Japan
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Kinematic and Chemical Constraints on the Formation of M31's Inner and Outer Halo

Koch, Andreas,   Rich, R. Michael,   Reitzel, David B.,   Martin, Nicolas F.,   Ibata, Rodrigo A.,   Chapman, Scott C.

The halo of M31 shows a wealth of substructures, some of which are consistent with assembly from satellite accretion. Here we report on kinematic and abundance results from Keck DEIMOS spectroscopy in the near-infrared calcium triplet region of over 3500 red giant star candidates along the minor axis and in...

December 2008   The Astrophysical Journal
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Suzaku broad-band spectroscopy of RX J1347.5-1145: constraints on the extremely hot gas and non-thermal emission

Ota, N.,   Murase, K.,   Kitayama, T.,   Komatsu, E.,   Hattori, M.,   Matsuo, H.

Context: We present the results of our analysis of long Suzaku observations (149 ks and 122 ks for XIS and HXD, respectively) of the most X-ray luminous galaxy cluster, RX J1347.5-1145, at z=0.451. Aims: To understand the gas physics of a violent, cluster merger, we study physical properties of the...

November 2008  
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Non-Equilibrium Ionization State and Two-Temperature Structure in the Linked Region of Abell 399 and Abell 401

Akahori, Takuya,   Yoshikawa, Kohji

We investigate a non-equilibrium ionization state and a two-temperature structure of the intracluster medium in the linked region of Abell 399 and Abell 401, using a series of N-body + Smoothed Particle Hydrodynamics (SPH) simulations, and find that there exist significant shock layers at the edge of the linked region...

August 2008   Publications of the Astronomical Society of Japan
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The impact of a supernova explosion in a very massive binary

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 100M$_solar$. In a Population III binary system, a more massive star can result in the formation of a black...

July 2008   Monthly Notices of the Royal Astronomical Society
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Nuclear/Circumnuclear Starbursts and Active Galactic Nucleus Mass Accretion in Seyfert Galaxies

Watabe, Yasuyuki,   Kawakatu, Nozomu,   Imanishi, Masatoshi

We investigated the correlation between nuclear/circumnuclear starbursts around active galactic nuclei (AGNs) and the AGN activities for 43 Seyfert galaxies in the CfA and 12 \ensuremathμm samples. We found that the circumnuclear starburst luminosity, as well as the nuclear starburst luminosity, is positively correlated with the AGN luminosity. Moreover, the...

April 2008   The Astrophysical Journal