Achievements & Publications

Galaxy-scale AGN feedback - theory

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Wagner, A.~Y.,   Bicknell, G.~V.,   Umemura, M.,   Sutherland , R.~S.,   Silk, J.

Powerful relativistic jets in radio galaxies are capable of driving strong outflows but also inducing star-formation by pressure- triggering collapse of dense clouds. We review theoretical work on negative and positive active galactic nuclei feedback, discussing insights gained from recent hydrodynamical simulations of jet-driven feedback on galaxy scales that are...

Radiation hydrodynamic simulations of line-driven disk winds for ultra-fast outflows

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Nomura, Mariko,   Ohsuga, Ken,   Takahashi, Hiroyuki R.,   Wada, Keiichi,   Yoshida, Tessei

Using two-dimensional radiation hydrodynamic simulations, we investigate the origin of the ultra-fast outflows (UFOs) that are often observed in luminous active galactic nuclei (AGNs). We found that the radiation force due to the spectral lines generates strong winds (line-driven disk winds) that are launched from the inner region of accretion...

Spectral Line Survey toward Molecular Clouds in the Large Magellanic Cloud

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Nishimura, Yuri,   Shimonishi, Takashi,   Watanabe, Yoshimasa,   Sakai, Nami,   Aikawa, Yuri,   Kawamura, Akiko

Spectral line survey observations of seven molecular clouds in the Large Magellanic Cloud (LMC) have been conducted in the 3 mm band with the Mopra 22 m telescope to reveal chemical compositions in low metallicity conditions. Spectral lines of fundamental species such as CS, SO, CCH, HCN, HCO$^+$, and HNC...

Reconstructing the history of water ice formation from HDO/H$_2$O and D$_2$O/HDO ratios in protostellar cores

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Furuya, K.,   van Dishoeck, E.~F.,   Aikawa, Y.

Recent interferometer observations have found that the D$_2$O/HDO abundance ratio is higher than that of HDO/H$_2$O by about one order of magnitude in the vicinity of low-mass protostar NGC 1333-IRAS 2A, where water ice has sublimated. Previous laboratory and theoretical studies show that the D$_2$O/HDO ice ratio should be lower...

Water deuteration and ortho-to-para nuclear spin ratio of H$_2$ in molecular clouds formed via the accumulation of H I gas

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Furuya, K.,   Aikawa, Y.,   Hincelin, U.,   Hassel, G.~E.,   Bergin, E.~A.,   Vasyunin, A.~I.

We investigate the water deuteration ratio and ortho-to-para nuclear spin ratio of H$_2$ (OPR(H$_2$)) during the formation and early evolution of a molecular cloud, following the scenario that accretion flows sweep and accumulate H i gas to form molecular clouds. We follow the physical evolution of post-shock materials using a...

Double DCO$^+$ Rings Reveal CO Ice Desorption in the Outer Disk Around IM Lup

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Öberg, Karin I.,   Furuya, Kenji,   Loomis, Ryan,   Aikawa, Yuri,   Andrews, Sean M.,   Qi, Chunhua

In a protoplanetary disk, a combination of thermal and non-thermal desorption processes regulate where volatiles are liberated from icy grain mantles into the gas phase. Non-thermal desorption should result in volatile-enriched gas in disk-regions where complete freeze-out is otherwise expected. We present Atacama Large Millimeter/Submillimeter Array observations of the disk...

A new ray-tracing scheme for 3D diffuse radiation transfer on highly parallel architectures

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Tanaka, Satoshi,   Yoshikawa, Kohji,   Okamoto, Takashi,   Hasegawa, Kenji

We present a new numerical scheme to solve the transfer of diffuse radiation on three-dimensional mesh grids which is efficient on processors with highly parallel architecture such as recently popular GPUs and CPUs with multi- and many-core architectures. The scheme is based on the ray-tracing method and the computational cost...

Early cosmic merger of multiple black holes

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Tagawa, H.,   Umemura, M.,   Gouda, N.,   Yano, T.,   Yamai, Y.

We perform numerical simulations on the merger of multiple black holes (BHs) in primordial gas at early cosmic epochs. We consider two cases of BH mass: M$_BH$ = 30 and 10$^4$ M$_☉$. Attention is concentrated on the effect of the dynamical friction by gas in a host object. The simulations...

Light absorption efficiencies of photosynthetic pigments: the dependence on spectral types of central stars

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Komatsu, Yu,   Umemura, Masayuki,   Shoji, Mitsuo,   Kayanuma, Megumi,   Yabana, Kazuhiro,   Shiraishi, Kenji

For detecting life from reflection spectra on extrasolar planets, trace of photosynthesis is one of the indicators. However, it is not yet clear what kind of radiation environments is acceptable for photosynthesis. Light absorption in photosystems on the Earth occurs using limited photosynthetic pigments such as chlorophylls (Chls) and bacteriochlorophylls...

Analytical Formulae of Molecular Ion Abundances and the N$_2$H$^+$ Ring in Protoplanetary Disks

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Aikawa, Yuri,   Furuya, Kenji,   Nomura, Hideko,   Qi, Chunhua

We investigate the chemistry of ion molecules in protoplanetary disks, motivated by the detection of the N$_2$H$^+$ ring around TW Hya. While the ring inner radius coincides with the CO snow line, it is not apparent why N$_2$H$^+$ is abundant outside the CO snow line in spite of the similar...

Light absorption and excitation energy transfer calculations in primitive photosynthetic bacteria

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Komatsu, Yu,   Kayanuma, Megumi,   Shoji, Mitsuo,   Yabana, Kazuhiro,   Shiraishi, Kenji,   Umemura, Masayuki

In photosynthetic organisms, light energy is converted into chemical energy through the light absorption and excitation energy transfer (EET) processes. These processes start in light- harvesting complexes, which contain special photosynthetic pigments. The exploration of unique mechanisms in light- harvesting complexes is directly related to studies, such as artificial photosynthesis...

IL-1 receptor antagonist-deficient mice develop autoimmune arthritis due to intrinsic activation of IL-17-producing CCR2$^+$V\ensuremathγ6$^+$\ensuremathγ\ensuremathδ T cells

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Akitsu, Aoi,   Ishigame, Harumichi,   Kakuta, Shigeru,   Chung, Soo-Hyun,   Ikeda, Satoshi,   Shimizu, Kenji

Interleukin-17 (IL-17)-producing \ensuremathγ\ensuremathδ T (\ensuremathγ\ensuremathδ17) cells have been implicated in inflammatory diseases, but the underlying pathogenic mechanisms remain unclear. Here, we show that both CD4$^+$ and \ensuremathγ\ensuremathδ17 cells are required for the development of autoimmune arthritis in IL-1 receptor antagonist (IL-1Ra)-deficient mice. Specifically, activated CD4$^+$ T cells direct \ensuremathγ\ensuremathδ T-cell...

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Galaxy-scale AGN feedback - theory

Wagner, A.~Y.,   Bicknell, G.~V.,   Umemura, M.,   Sutherland , R.~S.,   Silk, J.

Powerful relativistic jets in radio galaxies are capable of driving strong outflows but also inducing star-formation by pressure- triggering collapse of dense clouds. We review theoretical work on negative and positive active galactic nuclei feedback, discussing insights gained from recent hydrodynamical simulations of jet-driven feedback on galaxy scales that are...

February 2016  
Image

Radiation hydrodynamic simulations of line-driven disk winds for ultra-fast outflows

Nomura, Mariko,   Ohsuga, Ken,   Takahashi, Hiroyuki R.,   Wada, Keiichi,   Yoshida, Tessei

Using two-dimensional radiation hydrodynamic simulations, we investigate the origin of the ultra-fast outflows (UFOs) that are often observed in luminous active galactic nuclei (AGNs). We found that the radiation force due to the spectral lines generates strong winds (line-driven disk winds) that are launched from the inner region of accretion...

February 2016   Publications of the Astronomical Society of Japan
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Spectral Line Survey toward Molecular Clouds in the Large Magellanic Cloud

Nishimura, Yuri,   Shimonishi, Takashi,   Watanabe, Yoshimasa,   Sakai, Nami,   Aikawa, Yuri,   Kawamura, Akiko

Spectral line survey observations of seven molecular clouds in the Large Magellanic Cloud (LMC) have been conducted in the 3 mm band with the Mopra 22 m telescope to reveal chemical compositions in low metallicity conditions. Spectral lines of fundamental species such as CS, SO, CCH, HCN, HCO$^+$, and HNC...

February 2016   The Astrophysical Journal
Image

Reconstructing the history of water ice formation from HDO/H$_2$O and D$_2$O/HDO ratios in protostellar cores

Furuya, K.,   van Dishoeck, E.~F.,   Aikawa, Y.

Recent interferometer observations have found that the D$_2$O/HDO abundance ratio is higher than that of HDO/H$_2$O by about one order of magnitude in the vicinity of low-mass protostar NGC 1333-IRAS 2A, where water ice has sublimated. Previous laboratory and theoretical studies show that the D$_2$O/HDO ice ratio should be lower...

February 2016  
Image

Water deuteration and ortho-to-para nuclear spin ratio of H$_2$ in molecular clouds formed via the accumulation of H I gas

Furuya, K.,   Aikawa, Y.,   Hincelin, U.,   Hassel, G.~E.,   Bergin, E.~A.,   Vasyunin, A.~I.

We investigate the water deuteration ratio and ortho-to-para nuclear spin ratio of H$_2$ (OPR(H$_2$)) during the formation and early evolution of a molecular cloud, following the scenario that accretion flows sweep and accumulate H i gas to form molecular clouds. We follow the physical evolution of post-shock materials using a...

December 2015  
Image

Double DCO$^+$ Rings Reveal CO Ice Desorption in the Outer Disk Around IM Lup

Öberg, Karin I.,   Furuya, Kenji,   Loomis, Ryan,   Aikawa, Yuri,   Andrews, Sean M.,   Qi, Chunhua

In a protoplanetary disk, a combination of thermal and non-thermal desorption processes regulate where volatiles are liberated from icy grain mantles into the gas phase. Non-thermal desorption should result in volatile-enriched gas in disk-regions where complete freeze-out is otherwise expected. We present Atacama Large Millimeter/Submillimeter Array observations of the disk...

September 2015   The Astrophysical Journal
Image

A new ray-tracing scheme for 3D diffuse radiation transfer on highly parallel architectures

Tanaka, Satoshi,   Yoshikawa, Kohji,   Okamoto, Takashi,   Hasegawa, Kenji

We present a new numerical scheme to solve the transfer of diffuse radiation on three-dimensional mesh grids which is efficient on processors with highly parallel architecture such as recently popular GPUs and CPUs with multi- and many-core architectures. The scheme is based on the ray-tracing method and the computational cost...

August 2015   Publications of the Astronomical Society of Japan
Image

Early cosmic merger of multiple black holes

Tagawa, H.,   Umemura, M.,   Gouda, N.,   Yano, T.,   Yamai, Y.

We perform numerical simulations on the merger of multiple black holes (BHs) in primordial gas at early cosmic epochs. We consider two cases of BH mass: M$_BH$ = 30 and 10$^4$ M$_☉$. Attention is concentrated on the effect of the dynamical friction by gas in a host object. The simulations...

August 2015   Monthly Notices of the Royal Astronomical Society
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Light absorption efficiencies of photosynthetic pigments: the dependence on spectral types of central stars

Komatsu, Yu,   Umemura, Masayuki,   Shoji, Mitsuo,   Kayanuma, Megumi,   Yabana, Kazuhiro,   Shiraishi, Kenji

For detecting life from reflection spectra on extrasolar planets, trace of photosynthesis is one of the indicators. However, it is not yet clear what kind of radiation environments is acceptable for photosynthesis. Light absorption in photosystems on the Earth occurs using limited photosynthetic pigments such as chlorophylls (Chls) and bacteriochlorophylls...

July 2015  
Image

Analytical Formulae of Molecular Ion Abundances and the N$_2$H$^+$ Ring in Protoplanetary Disks

Aikawa, Yuri,   Furuya, Kenji,   Nomura, Hideko,   Qi, Chunhua

We investigate the chemistry of ion molecules in protoplanetary disks, motivated by the detection of the N$_2$H$^+$ ring around TW Hya. While the ring inner radius coincides with the CO snow line, it is not apparent why N$_2$H$^+$ is abundant outside the CO snow line in spite of the similar...

July 2015   The Astrophysical Journal
Image

Light absorption and excitation energy transfer calculations in primitive photosynthetic bacteria

Komatsu, Yu,   Kayanuma, Megumi,   Shoji, Mitsuo,   Yabana, Kazuhiro,   Shiraishi, Kenji,   Umemura, Masayuki

In photosynthetic organisms, light energy is converted into chemical energy through the light absorption and excitation energy transfer (EET) processes. These processes start in light- harvesting complexes, which contain special photosynthetic pigments. The exploration of unique mechanisms in light- harvesting complexes is directly related to studies, such as artificial photosynthesis...

June 2015  
Image

IL-1 receptor antagonist-deficient mice develop autoimmune arthritis due to intrinsic activation of IL-17-producing CCR2$^+$V\ensuremathγ6$^+$\ensuremathγ\ensuremathδ T cells

Akitsu, Aoi,   Ishigame, Harumichi,   Kakuta, Shigeru,   Chung, Soo-Hyun,   Ikeda, Satoshi,   Shimizu, Kenji

Interleukin-17 (IL-17)-producing \ensuremathγ\ensuremathδ T (\ensuremathγ\ensuremathδ17) cells have been implicated in inflammatory diseases, but the underlying pathogenic mechanisms remain unclear. Here, we show that both CD4$^+$ and \ensuremathγ\ensuremathδ17 cells are required for the development of autoimmune arthritis in IL-1 receptor antagonist (IL-1Ra)-deficient mice. Specifically, activated CD4$^+$ T cells direct \ensuremathγ\ensuremathδ T-cell...

June 2015  

Galaxy-scale AGN feedback - theory

Wagner, A.~Y.,   Bicknell, G.~V.,   Umemura, M.,   Sutherland , R.~S.,   Silk, J.
February 2016  

Radiation hydrodynamic simulations of line-driven disk winds for ultra-fast outflows

Nomura, Mariko,   Ohsuga, Ken,   Takahashi, Hiroyuki R.,   Wada, Keiichi,   Yoshida, Tessei
February 2016   Publications of the Astronomical Society of Japan

Spectral Line Survey toward Molecular Clouds in the Large Magellanic Cloud

Nishimura, Yuri,   Shimonishi, Takashi,   Watanabe, Yoshimasa,   Sakai, Nami,   Aikawa, Yuri,   Kawamura, Akiko
February 2016   The Astrophysical Journal

Reconstructing the history of water ice formation from HDO/H$_2$O and D$_2$O/HDO ratios in protostellar cores

Furuya, K.,   van Dishoeck, E.~F.,   Aikawa, Y.
February 2016  

Water deuteration and ortho-to-para nuclear spin ratio of H$_2$ in molecular clouds formed via the accumulation of H I gas

Furuya, K.,   Aikawa, Y.,   Hincelin, U.,   Hassel, G.~E.,   Bergin, E.~A.,   Vasyunin, A.~I.
December 2015  

Double DCO$^+$ Rings Reveal CO Ice Desorption in the Outer Disk Around IM Lup

Öberg, Karin I.,   Furuya, Kenji,   Loomis, Ryan,   Aikawa, Yuri,   Andrews, Sean M.,   Qi, Chunhua
September 2015   The Astrophysical Journal

A new ray-tracing scheme for 3D diffuse radiation transfer on highly parallel architectures

Tanaka, Satoshi,   Yoshikawa, Kohji,   Okamoto, Takashi,   Hasegawa, Kenji
August 2015   Publications of the Astronomical Society of Japan

Early cosmic merger of multiple black holes

Tagawa, H.,   Umemura, M.,   Gouda, N.,   Yano, T.,   Yamai, Y.
August 2015   Monthly Notices of the Royal Astronomical Society

Light absorption efficiencies of photosynthetic pigments: the dependence on spectral types of central stars

Komatsu, Yu,   Umemura, Masayuki,   Shoji, Mitsuo,   Kayanuma, Megumi,   Yabana, Kazuhiro,   Shiraishi, Kenji
July 2015  

Analytical Formulae of Molecular Ion Abundances and the N$_2$H$^+$ Ring in Protoplanetary Disks

Aikawa, Yuri,   Furuya, Kenji,   Nomura, Hideko,   Qi, Chunhua
July 2015   The Astrophysical Journal

Light absorption and excitation energy transfer calculations in primitive photosynthetic bacteria

Komatsu, Yu,   Kayanuma, Megumi,   Shoji, Mitsuo,   Yabana, Kazuhiro,   Shiraishi, Kenji,   Umemura, Masayuki
June 2015  

IL-1 receptor antagonist-deficient mice develop autoimmune arthritis due to intrinsic activation of IL-17-producing CCR2$^+$V\ensuremathγ6$^+$\ensuremathγ\ensuremathδ T cells

Akitsu, Aoi,   Ishigame, Harumichi,   Kakuta, Shigeru,   Chung, Soo-Hyun,   Ikeda, Satoshi,   Shimizu, Kenji
June 2015