Achievements & Publications

N-body simulation for self-gravitating collisional systems with a new SIMD instruction set extension to the x86 architecture, Advanced Vector eXtensions

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Tanikawa, Ataru,   Yoshikawa, Kohji,   Okamoto, Takashi,   Nitadori, Keigo

We present a high-performance N-body code for self-gravitating collisional systems accelerated with the aid of a new SIMD instruction set extension of the x86 architecture: Advanced Vector eXtensions (AVX), an enhanced version of the Streaming SIMD Extensions (SSE). With one processor core of Intel Core i7-2600 processor (8 MB cache...

ARGOT: accelerated radiative transfer on grids using oct-tree

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Okamoto, Takashi,   Yoshikawa, Kohji,   Umemura, Masayuki

We present two types of numerical prescriptions that accelerate the radiative transfer calculation around point sources within a three-dimensional Cartesian grid by using the oct-tree structure for the distribution of radiation sources. In one prescription, distant radiation sources are grouped as a bright extended source when the group's angular size,...

Stereo pairs in Astrophysics

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Vogt, Frédéric,   Wagner, Alexander Y.

Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation...

New method for exploring super-Eddington active galactic nuclei by near-infrared observations

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Kawakatu, N.,   Ohsuga, K.

We propose a new method to explore the candidate super-Eddington active galactic nuclei (AGNs). We examine the properties of infrared (IR) emission from the inner edge of the dusty torus in AGNs, which are powered by super- or sub-Eddington accretion flows around black holes, by considering the dependence of the...

A high-frequency study of the Sunyaev-Zel'dovich effect morphology in galaxy clusters

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Prokhorov, D.~A.,   Colafrancesco, S.,   Akahori, T.,   Million, E.~T.,   Nagataki, S.,   Yoshikawa, K.

High-frequency, high-resolution imaging of the Sunyaev-Zel'dovich (SZ) effect is an important technique to study the complex structures of the atmospheres of merging galaxy clusters. Such observations are sensitive to the details of the electron spectrum. We show that the morphology of the SZ intensity maps in simulated galaxy clusters observed...

Unveiling the 3D temperature structure of galaxy clusters by means of the thermal Sunyaev-Zel'dovich effect

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Prokhorov, D.~A.,   Dubois, Y.,   Nagataki, S.,   Akahori, T.,   Yoshikawa, K.

The Sunyaev-Zel'dovich (hereinafter SZ) effect is a promising tool to derive the gas temperature of galaxy clusters. Approximation of a spherically symmetric gas distribution is usually used to determine the temperature structure of galaxy clusters, but this approximation cannot properly describe merging galaxy clusters. The methods used so far, which...

Near-infrared Reverberation by Dusty Clumpy Tori in Active Galactic Nuclei

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Kawaguchi, Toshihiro,   Mori, Masao

According to recent models, the accretion disk and black hole in active galactic nuclei (AGNs) are surrounded by a clumpy torus. We investigate the NIR flux variation of the torus in response to a UV flash for various geometries. Anisotropic illumination by the disk and the torus self-occultation contrast our...

The Core-Cusp Problem in Cold Dark Matter Halos and Supernova Feedback: Effects of Mass Loss

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Ogiya, Go,   Mori, Masao

The core-cusp problem remains as one of the unsolved discrepancies between observations and theories predicted by the standard paradigm of cold dark matter (CDM) cosmology. To solve this problem, we perform N-body simulations to study the nonlinear response of CDM halos to the variance of the gravitational potential induced by...

Can electron distribution functions be derived through the Sunyaev-Zel'dovich effect?

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Prokhorov, D.~A.,   Colafrancesco, S.,   Akahori, T.,   Yoshikawa, K.,   Nagataki, S.,   Seon, K. -I.

Aims: Measurements of the Sunyaev-Zel'dovich (hereafter SZ) effect distortion of the cosmic microwave background provide methods to derive the gas pressure and temperature of galaxy clusters. Here we study the ability of SZ effect observations to derive the electron distribution function (DF) in massive galaxy clusters. Methods: Our calculations of...

Evolution of Non-thermal Shell Emission Associated with Active Galactic Nucleus Jets

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Ito, Hirotaka,   Kino, Motoki,   Kawakatu, Nozomu,   Yamada, Shoichi

We explore the evolution of emissions by accelerated electrons in shocked shells driven by jets in active galactic nuclei. Focusing on powerful sources which host luminous quasars, we evaluated the broadband emission spectra by properly taking into account adiabatic and radiative cooling effects on the electron distribution. The synchrotron radiation...

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N-body simulation for self-gravitating collisional systems with a new SIMD instruction set extension to the x86 architecture, Advanced Vector eXtensions

Tanikawa, Ataru,   Yoshikawa, Kohji,   Okamoto, Takashi,   Nitadori, Keigo

We present a high-performance N-body code for self-gravitating collisional systems accelerated with the aid of a new SIMD instruction set extension of the x86 architecture: Advanced Vector eXtensions (AVX), an enhanced version of the Streaming SIMD Extensions (SSE). With one processor core of Intel Core i7-2600 processor (8 MB cache...

February 2012   New Astronomy
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ARGOT: accelerated radiative transfer on grids using oct-tree

Okamoto, Takashi,   Yoshikawa, Kohji,   Umemura, Masayuki

We present two types of numerical prescriptions that accelerate the radiative transfer calculation around point sources within a three-dimensional Cartesian grid by using the oct-tree structure for the distribution of radiation sources. In one prescription, distant radiation sources are grouped as a bright extended source when the group's angular size,...

February 2012   Monthly Notices of the Royal Astronomical Society
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Stereo pairs in Astrophysics

Vogt, Frédéric,   Wagner, Alexander Y.

Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation...

January 2012   Applied Surface Science
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New method for exploring super-Eddington active galactic nuclei by near-infrared observations

Kawakatu, N.,   Ohsuga, K.

We propose a new method to explore the candidate super-Eddington active galactic nuclei (AGNs). We examine the properties of infrared (IR) emission from the inner edge of the dusty torus in AGNs, which are powered by super- or sub-Eddington accretion flows around black holes, by considering the dependence of the...

November 2011   Monthly Notices of the Royal Astronomical Society
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A high-frequency study of the Sunyaev-Zel'dovich effect morphology in galaxy clusters

Prokhorov, D.~A.,   Colafrancesco, S.,   Akahori, T.,   Million, E.~T.,   Nagataki, S.,   Yoshikawa, K.

High-frequency, high-resolution imaging of the Sunyaev-Zel'dovich (SZ) effect is an important technique to study the complex structures of the atmospheres of merging galaxy clusters. Such observations are sensitive to the details of the electron spectrum. We show that the morphology of the SZ intensity maps in simulated galaxy clusters observed...

September 2011   Monthly Notices of the Royal Astronomical Society
Image

Unveiling the 3D temperature structure of galaxy clusters by means of the thermal Sunyaev-Zel'dovich effect

Prokhorov, D.~A.,   Dubois, Y.,   Nagataki, S.,   Akahori, T.,   Yoshikawa, K.

The Sunyaev-Zel'dovich (hereinafter SZ) effect is a promising tool to derive the gas temperature of galaxy clusters. Approximation of a spherically symmetric gas distribution is usually used to determine the temperature structure of galaxy clusters, but this approximation cannot properly describe merging galaxy clusters. The methods used so far, which...

August 2011   Monthly Notices of the Royal Astronomical Society
Image

Near-infrared Reverberation by Dusty Clumpy Tori in Active Galactic Nuclei

Kawaguchi, Toshihiro,   Mori, Masao

According to recent models, the accretion disk and black hole in active galactic nuclei (AGNs) are surrounded by a clumpy torus. We investigate the NIR flux variation of the torus in response to a UV flash for various geometries. Anisotropic illumination by the disk and the torus self-occultation contrast our...

August 2011   The Astrophysical Journal
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The Core-Cusp Problem in Cold Dark Matter Halos and Supernova Feedback: Effects of Mass Loss

Ogiya, Go,   Mori, Masao

The core-cusp problem remains as one of the unsolved discrepancies between observations and theories predicted by the standard paradigm of cold dark matter (CDM) cosmology. To solve this problem, we perform N-body simulations to study the nonlinear response of CDM halos to the variance of the gravitational potential induced by...

July 2011   The Astrophysical Journal Letters
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Can electron distribution functions be derived through the Sunyaev-Zel'dovich effect?

Prokhorov, D.~A.,   Colafrancesco, S.,   Akahori, T.,   Yoshikawa, K.,   Nagataki, S.,   Seon, K. -I.

Aims: Measurements of the Sunyaev-Zel'dovich (hereafter SZ) effect distortion of the cosmic microwave background provide methods to derive the gas pressure and temperature of galaxy clusters. Here we study the ability of SZ effect observations to derive the electron distribution function (DF) in massive galaxy clusters. Methods: Our calculations of...

May 2011  
Image

Evolution of Non-thermal Shell Emission Associated with Active Galactic Nucleus Jets

Ito, Hirotaka,   Kino, Motoki,   Kawakatu, Nozomu,   Yamada, Shoichi

We explore the evolution of emissions by accelerated electrons in shocked shells driven by jets in active galactic nuclei. Focusing on powerful sources which host luminous quasars, we evaluated the broadband emission spectra by properly taking into account adiabatic and radiative cooling effects on the electron distribution. The synchrotron radiation...

April 2011   The Astrophysical Journal

N-body simulation for self-gravitating collisional systems with a new SIMD instruction set extension to the x86 architecture, Advanced Vector eXtensions

Tanikawa, Ataru,   Yoshikawa, Kohji,   Okamoto, Takashi,   Nitadori, Keigo
February 2012   New Astronomy

ARGOT: accelerated radiative transfer on grids using oct-tree

Okamoto, Takashi,   Yoshikawa, Kohji,   Umemura, Masayuki
February 2012   Monthly Notices of the Royal Astronomical Society

Stereo pairs in Astrophysics

Vogt, Frédéric,   Wagner, Alexander Y.
January 2012   Applied Surface Science

New method for exploring super-Eddington active galactic nuclei by near-infrared observations

Kawakatu, N.,   Ohsuga, K.
November 2011   Monthly Notices of the Royal Astronomical Society

A high-frequency study of the Sunyaev-Zel'dovich effect morphology in galaxy clusters

Prokhorov, D.~A.,   Colafrancesco, S.,   Akahori, T.,   Million, E.~T.,   Nagataki, S.,   Yoshikawa, K.
September 2011   Monthly Notices of the Royal Astronomical Society

Unveiling the 3D temperature structure of galaxy clusters by means of the thermal Sunyaev-Zel'dovich effect

Prokhorov, D.~A.,   Dubois, Y.,   Nagataki, S.,   Akahori, T.,   Yoshikawa, K.
August 2011   Monthly Notices of the Royal Astronomical Society

Near-infrared Reverberation by Dusty Clumpy Tori in Active Galactic Nuclei

Kawaguchi, Toshihiro,   Mori, Masao
August 2011   The Astrophysical Journal

The Core-Cusp Problem in Cold Dark Matter Halos and Supernova Feedback: Effects of Mass Loss

Ogiya, Go,   Mori, Masao
July 2011   The Astrophysical Journal Letters

Can electron distribution functions be derived through the Sunyaev-Zel'dovich effect?

Prokhorov, D.~A.,   Colafrancesco, S.,   Akahori, T.,   Yoshikawa, K.,   Nagataki, S.,   Seon, K. -I.
May 2011  

Evolution of Non-thermal Shell Emission Associated with Active Galactic Nucleus Jets

Ito, Hirotaka,   Kino, Motoki,   Kawakatu, Nozomu,   Yamada, Shoichi
April 2011   The Astrophysical Journal