Achievements & Publications

Discrimination of heavy elements originating from Pop III stars in z = 3 intergalactic medium

Image

Kirihara, Takanobu,   Hasegawa, Kenji,   Umemura, Masayuki,   Mori, Masao,   Ishiyama, Tomoaki

We investigate the distribution of metals in the cosmological volume at z \ensuremath∼ 3, in particular, provided by massive Population III (Pop III) stars using a cosmological N-body simulation in which a model of Pop III star formation is implemented. Owing to the simulation, we can choose minihaloes where Pop...

Spiral-arm instability - III. Fragmentation of primordial protostellar discs

Image

Inoue, Shigeki,   Yoshida, Naoki

We study the gravitational instability and fragmentation of primordial protostellar discs by using high-resolution cosmological hydrodynamics simulations. We follow the formation and evolution of spiral arms in protostellar discs, examine the dynamical stability, and identify a physical mechanism of secondary protostar formation. We use linear perturbation theory based on the...

The thermal-radiative wind in low-mass X-ray binary H1743-322: radiation hydrodynamic simulations

Image

Tomaru, Ryota,   Done, Chris,   Ohsuga, Ken,   Nomura, Mariko,   Takahashi, Tadayuki

Blueshifted absorption lines are seen in high inclination black hole binary systems in their disc-dominated states, showing these power an equatorial disc wind. While some contribution from magnetic winds remain a possibility, thermal and thermal- radiative winds are expected to be present. We show results from radiation hydrodynamic simulations that...

First Identification of 10 kpc [C II] 158 \ensuremathμm Halos around Star-forming Galaxies at z = 5─7

Image

Fujimoto, Seiji,   Ouchi, Masami,   Ferrara, Andrea,   Pallottini, Andrea,   Ivison, R.~J.,   Behrens, Christoph

We report the discovery of 10 kpc [C II] 158 \ensuremathμm halos surrounding star-forming galaxies in the early universe. We choose deep Atacama Large Millimeter/submillimeter Array data for 18 galaxies, each with a star formation rate of ≃10─70 M $_☉$ with no signature of an active galactic nucleus whose [C...

Searching for signs of jet-driven negative feedback in the nearby radio galaxy UGC 05771

Image

Zovaro, Henry R.~M.,   Nesvadba, Nicole P.~H.,   Sharp, Robert,   Bicknell, Geoffrey V.,   Groves, Brent,   Mukherjee, Dipanjan

Hydrodynamical simulations predict that the jets of young radio sources can inhibit star formation in their host galaxies by injecting heat and turbulence into the interstellar medium (ISM). To investigate jet-ISM interactions in a galaxy with a young radio source, we have carried out a multiwavelength study of the z...

Abundant Refractory Sulfur in Protoplanetary Disks

Image

Kama, Mihkel,   Shorttle, Oliver,   Jermyn, Adam S.,   Folsom, Colin P.,   Furuya, Kenji,   Bergin, Edwin A.

Sulfur is one of the most abundant elements in the universe, with important roles in astro-, geo-, and biochemistry. Its main reservoirs in planet-forming disks have previously eluded detection: gaseous molecules only account for <1% of total elemental sulfur, with the rest likely in either ices or refractory minerals. We...

ALMA observations of water deuteration: a physical diagnostic of the formation of protostars

Image

Jensen, S.~S.,   Jørgensen, J.~K.,   Kristensen, L.~E.,   Furuya, K.,   Coutens, A.,   van Dishoeck, E.~F.

Context. How water is delivered to planetary systems is a central question in astrochemistry. The deuterium fractionation of water can serve as a tracer for the chemical and physical evolution of water during star formation and can constrain the origin of water in Solar System bodies. Aims: The aim is...

Super-Eddington growth of black holes in the early universe: effects of disc radiation spectra

Image

Takeo, Eishun,   Inayoshi, Kohei,   Ohsuga, Ken,   Takahashi, Hiroyuki R.,   Mineshige, Shin

We investigate the properties of accretion flows on to a black hole (BH) with a mass of M$_BH$ embedded in an initially uniform gas cloud with a density of n$_\ensuremathınfty$ in order to study rapid growth of BHs in the early Universe. In previous work, the conditions required for super-Eddington...

Feedback from low-luminosity radio galaxies: B2 0258+35

Image

Murthy, Suma,   Morganti, Raffaella,   Oosterloo, Tom,   Schulz, Robert,   Mukherjee, Dipanjan,   Wagner, Alexander Y.

Low-luminosity radio-loud active galactic nuclei (AGN) are of importance in studies concerning feedback from radio AGN since a dominant fraction of AGN belong to this class. We report high-resolution Very Large Array (VLA) and European VLBI Network (EVN) observations of H I 21 cm absorption from a young, compact steep-spectrum...

Clumpy galaxies in cosmological simulations: the effect of ISM model

Image

Inoue, Shigeki,   Yoshida, Naoki

We study influence by models of interstellar medium (ISM) on properties of galaxies in cosmological simulations. We examine three models widely used in previous studies. The ISM models impose different equations of state on dense gas. Using zoom-in simulations, we demonstrate that switching the ISM models can control formation of...

H$_2$ Ortho-Para Spin Conversion on Inhomogeneous Grain Surfaces

Image

Furuya, Kenji,   Aikawa, Yuri,   Hama, Tetsuya,   Watanabe, Naoki

We investigate the evolution of the ortho-to-para ratio of overall (gas + ice) \\\H\\\$_2$ via the nuclear spin conversion on grain surfaces coated with water ice under physical conditions that are relevant to star- and planet-forming regions. We utilize the rate equation model that considers adsorption of gaseous \\\H\\\$_2$ on...

Radiative properties of the first galaxies: rapid transition between UV and infrared bright phases

Image

Arata, Shohei,   Yajima, Hidenobu,   Nagamine, Kentaro,   Li, Yuexing,   Khochfar, Sadegh

Recent observations have successfully detected UV-bright and infrared- bright galaxies in the epoch of reionization. However, the origin of their radiative properties has not been understood yet. Combining cosmological hydrodynamic simulations and radiative transfer calculations, we present predictions of multiwavelength radiative properties of the first galaxies at z ̃ 6-15....

Magnetohydrodynamic simulation code CANS+: Assessments and applications

Image

Matsumoto, Yosuke,   Asahina, Yuta,   Kudoh, Yuki,   Kawashima, Tomohisa,   Matsumoto, Jin,   Takahashi, Hiroyuki R.

We present a new magnetohydrodynamic (MHD) simulation package with the aim of providing accurate numerical solutions to astrophysical phenomena where discontinuities, shock waves, and turbulence are inherently important. The code implements the Harten-Lax-van Leer-discontinuitues (HLLD) approximate Riemann solver, the fifth-order-monotonicity-preserving interpolation (MP5) scheme, and the hyperbolic divergence cleaning method for...

On the dynamics and survival of fractal clouds in galactic winds

Image

Banda-Barragán, W.~E.,   Zertuche, F.~J.,   Federrath, C.,   Garcı́a Del Valle, J.,   Brüggen, M.,   Wagner, A.~Y.

Recent observations suggest that dense gas clouds can survive even in hot galactic winds. Here we show that the inclusion of turbulent densities with different statistical properties has significant effects on the evolution of wind-swept clouds. We investigate how the initial standard deviation of the lognormal density field influences the...

Jets blowing bubbles in the young radio galaxy 4C 31.04

Image

Zovaro, Henry R.~M.,   Sharp, Robert,   Nesvadba, Nicole P.~H.,   Bicknell, Geoffrey V.,   Mukherjee, Dipanjan,   Wagner, Alexand er Y.

We report the discovery of shocked molecular and ionized gas resulting from jet-driven feedback in the low-redshift (z = 0.0602) compact radio galaxy 4C 31.04 using near-IR imaging spectroscopy. 4C 31.04 is a ̃100 pc double-lobed Compact Steep Spectrum source believed to be a very young active galactic nucleus (AGN)....

Osaka feedback model: isolated disc galaxy simulations

Image

Shimizu, Ikkoh,   Todoroki, Keita,   Yajima, Hidenobu,   Nagamine, Kentaro

We study various implementations of a supernova (SN) feedback model and present the results of our `Osaka feedback model' using isolated galaxy simulations performed by the smoothed particle hydrodynamics code GADGET-3. Our model is a modified version of Stinson et al.'s work, and we newly add the momentum kick for...

Image

Discrimination of heavy elements originating from Pop III stars in z = 3 intergalactic medium

Kirihara, Takanobu,   Hasegawa, Kenji,   Umemura, Masayuki,   Mori, Masao,   Ishiyama, Tomoaki

We investigate the distribution of metals in the cosmological volume at z \ensuremath∼ 3, in particular, provided by massive Population III (Pop III) stars using a cosmological N-body simulation in which a model of Pop III star formation is implemented. Owing to the simulation, we can choose minihaloes where Pop...

January 2020   Monthly Notices of the Royal Astronomical Society
Image

Spiral-arm instability - III. Fragmentation of primordial protostellar discs

Inoue, Shigeki,   Yoshida, Naoki

We study the gravitational instability and fragmentation of primordial protostellar discs by using high-resolution cosmological hydrodynamics simulations. We follow the formation and evolution of spiral arms in protostellar discs, examine the dynamical stability, and identify a physical mechanism of secondary protostar formation. We use linear perturbation theory based on the...

January 2020   Monthly Notices of the Royal Astronomical Society
Image

The thermal-radiative wind in low-mass X-ray binary H1743-322: radiation hydrodynamic simulations

Tomaru, Ryota,   Done, Chris,   Ohsuga, Ken,   Nomura, Mariko,   Takahashi, Tadayuki

Blueshifted absorption lines are seen in high inclination black hole binary systems in their disc-dominated states, showing these power an equatorial disc wind. While some contribution from magnetic winds remain a possibility, thermal and thermal- radiative winds are expected to be present. We show results from radiation hydrodynamic simulations that...

December 2019   Monthly Notices of the Royal Astronomical Society
Image

First Identification of 10 kpc [C II] 158 \ensuremathμm Halos around Star-forming Galaxies at z = 5─7

Fujimoto, Seiji,   Ouchi, Masami,   Ferrara, Andrea,   Pallottini, Andrea,   Ivison, R.~J.,   Behrens, Christoph

We report the discovery of 10 kpc [C II] 158 \ensuremathμm halos surrounding star-forming galaxies in the early universe. We choose deep Atacama Large Millimeter/submillimeter Array data for 18 galaxies, each with a star formation rate of ≃10─70 M $_☉$ with no signature of an active galactic nucleus whose [C...

December 2019   The Astrophysical Journal
Image

Searching for signs of jet-driven negative feedback in the nearby radio galaxy UGC 05771

Zovaro, Henry R.~M.,   Nesvadba, Nicole P.~H.,   Sharp, Robert,   Bicknell, Geoffrey V.,   Groves, Brent,   Mukherjee, Dipanjan

Hydrodynamical simulations predict that the jets of young radio sources can inhibit star formation in their host galaxies by injecting heat and turbulence into the interstellar medium (ISM). To investigate jet-ISM interactions in a galaxy with a young radio source, we have carried out a multiwavelength study of the z...

November 2019   Monthly Notices of the Royal Astronomical Society
Image

Abundant Refractory Sulfur in Protoplanetary Disks

Kama, Mihkel,   Shorttle, Oliver,   Jermyn, Adam S.,   Folsom, Colin P.,   Furuya, Kenji,   Bergin, Edwin A.

Sulfur is one of the most abundant elements in the universe, with important roles in astro-, geo-, and biochemistry. Its main reservoirs in planet-forming disks have previously eluded detection: gaseous molecules only account for <1% of total elemental sulfur, with the rest likely in either ices or refractory minerals. We...

November 2019   The Astrophysical Journal
Image

ALMA observations of water deuteration: a physical diagnostic of the formation of protostars

Jensen, S.~S.,   Jørgensen, J.~K.,   Kristensen, L.~E.,   Furuya, K.,   Coutens, A.,   van Dishoeck, E.~F.

Context. How water is delivered to planetary systems is a central question in astrochemistry. The deuterium fractionation of water can serve as a tracer for the chemical and physical evolution of water during star formation and can constrain the origin of water in Solar System bodies. Aims: The aim is...

November 2019  
Image

Super-Eddington growth of black holes in the early universe: effects of disc radiation spectra

Takeo, Eishun,   Inayoshi, Kohei,   Ohsuga, Ken,   Takahashi, Hiroyuki R.,   Mineshige, Shin

We investigate the properties of accretion flows on to a black hole (BH) with a mass of M$_BH$ embedded in an initially uniform gas cloud with a density of n$_\ensuremathınfty$ in order to study rapid growth of BHs in the early Universe. In previous work, the conditions required for super-Eddington...

September 2019   Monthly Notices of the Royal Astronomical Society
Image

Feedback from low-luminosity radio galaxies: B2 0258+35

Murthy, Suma,   Morganti, Raffaella,   Oosterloo, Tom,   Schulz, Robert,   Mukherjee, Dipanjan,   Wagner, Alexander Y.

Low-luminosity radio-loud active galactic nuclei (AGN) are of importance in studies concerning feedback from radio AGN since a dominant fraction of AGN belong to this class. We report high-resolution Very Large Array (VLA) and European VLBI Network (EVN) observations of H I 21 cm absorption from a young, compact steep-spectrum...

September 2019  
Image

Clumpy galaxies in cosmological simulations: the effect of ISM model

Inoue, Shigeki,   Yoshida, Naoki

We study influence by models of interstellar medium (ISM) on properties of galaxies in cosmological simulations. We examine three models widely used in previous studies. The ISM models impose different equations of state on dense gas. Using zoom-in simulations, we demonstrate that switching the ISM models can control formation of...

September 2019   Monthly Notices of the Royal Astronomical Society
Image

H$_2$ Ortho-Para Spin Conversion on Inhomogeneous Grain Surfaces

Furuya, Kenji,   Aikawa, Yuri,   Hama, Tetsuya,   Watanabe, Naoki

We investigate the evolution of the ortho-to-para ratio of overall (gas + ice) \\\H\\\$_2$ via the nuclear spin conversion on grain surfaces coated with water ice under physical conditions that are relevant to star- and planet-forming regions. We utilize the rate equation model that considers adsorption of gaseous \\\H\\\$_2$ on...

September 2019   The Astrophysical Journal
Image

Radiative properties of the first galaxies: rapid transition between UV and infrared bright phases

Arata, Shohei,   Yajima, Hidenobu,   Nagamine, Kentaro,   Li, Yuexing,   Khochfar, Sadegh

Recent observations have successfully detected UV-bright and infrared- bright galaxies in the epoch of reionization. However, the origin of their radiative properties has not been understood yet. Combining cosmological hydrodynamic simulations and radiative transfer calculations, we present predictions of multiwavelength radiative properties of the first galaxies at z ̃ 6-15....

September 2019   Monthly Notices of the Royal Astronomical Society
Image

Magnetohydrodynamic simulation code CANS+: Assessments and applications

Matsumoto, Yosuke,   Asahina, Yuta,   Kudoh, Yuki,   Kawashima, Tomohisa,   Matsumoto, Jin,   Takahashi, Hiroyuki R.

We present a new magnetohydrodynamic (MHD) simulation package with the aim of providing accurate numerical solutions to astrophysical phenomena where discontinuities, shock waves, and turbulence are inherently important. The code implements the Harten-Lax-van Leer-discontinuitues (HLLD) approximate Riemann solver, the fifth-order-monotonicity-preserving interpolation (MP5) scheme, and the hyperbolic divergence cleaning method for...

August 2019   Publications of the Astronomical Society of Japan
Image

On the dynamics and survival of fractal clouds in galactic winds

Banda-Barragán, W.~E.,   Zertuche, F.~J.,   Federrath, C.,   Garcı́a Del Valle, J.,   Brüggen, M.,   Wagner, A.~Y.

Recent observations suggest that dense gas clouds can survive even in hot galactic winds. Here we show that the inclusion of turbulent densities with different statistical properties has significant effects on the evolution of wind-swept clouds. We investigate how the initial standard deviation of the lognormal density field influences the...

July 2019   Monthly Notices of the Royal Astronomical Society
Image

Jets blowing bubbles in the young radio galaxy 4C 31.04

Zovaro, Henry R.~M.,   Sharp, Robert,   Nesvadba, Nicole P.~H.,   Bicknell, Geoffrey V.,   Mukherjee, Dipanjan,   Wagner, Alexand er Y.

We report the discovery of shocked molecular and ionized gas resulting from jet-driven feedback in the low-redshift (z = 0.0602) compact radio galaxy 4C 31.04 using near-IR imaging spectroscopy. 4C 31.04 is a ̃100 pc double-lobed Compact Steep Spectrum source believed to be a very young active galactic nucleus (AGN)....

April 2019   Monthly Notices of the Royal Astronomical Society
Image

Osaka feedback model: isolated disc galaxy simulations

Shimizu, Ikkoh,   Todoroki, Keita,   Yajima, Hidenobu,   Nagamine, Kentaro

We study various implementations of a supernova (SN) feedback model and present the results of our `Osaka feedback model' using isolated galaxy simulations performed by the smoothed particle hydrodynamics code GADGET-3. Our model is a modified version of Stinson et al.'s work, and we newly add the momentum kick for...

April 2019   Monthly Notices of the Royal Astronomical Society

Discrimination of heavy elements originating from Pop III stars in z = 3 intergalactic medium

Kirihara, Takanobu,   Hasegawa, Kenji,   Umemura, Masayuki,   Mori, Masao,   Ishiyama, Tomoaki
January 2020   Monthly Notices of the Royal Astronomical Society

Spiral-arm instability - III. Fragmentation of primordial protostellar discs

Inoue, Shigeki,   Yoshida, Naoki
January 2020   Monthly Notices of the Royal Astronomical Society

The thermal-radiative wind in low-mass X-ray binary H1743-322: radiation hydrodynamic simulations

Tomaru, Ryota,   Done, Chris,   Ohsuga, Ken,   Nomura, Mariko,   Takahashi, Tadayuki
December 2019   Monthly Notices of the Royal Astronomical Society

First Identification of 10 kpc [C II] 158 \ensuremathμm Halos around Star-forming Galaxies at z = 5─7

Fujimoto, Seiji,   Ouchi, Masami,   Ferrara, Andrea,   Pallottini, Andrea,   Ivison, R.~J.,   Behrens, Christoph
December 2019   The Astrophysical Journal

Searching for signs of jet-driven negative feedback in the nearby radio galaxy UGC 05771

Zovaro, Henry R.~M.,   Nesvadba, Nicole P.~H.,   Sharp, Robert,   Bicknell, Geoffrey V.,   Groves, Brent,   Mukherjee, Dipanjan
November 2019   Monthly Notices of the Royal Astronomical Society

Abundant Refractory Sulfur in Protoplanetary Disks

Kama, Mihkel,   Shorttle, Oliver,   Jermyn, Adam S.,   Folsom, Colin P.,   Furuya, Kenji,   Bergin, Edwin A.
November 2019   The Astrophysical Journal

ALMA observations of water deuteration: a physical diagnostic of the formation of protostars

Jensen, S.~S.,   Jørgensen, J.~K.,   Kristensen, L.~E.,   Furuya, K.,   Coutens, A.,   van Dishoeck, E.~F.
November 2019  

Super-Eddington growth of black holes in the early universe: effects of disc radiation spectra

Takeo, Eishun,   Inayoshi, Kohei,   Ohsuga, Ken,   Takahashi, Hiroyuki R.,   Mineshige, Shin
September 2019   Monthly Notices of the Royal Astronomical Society

Feedback from low-luminosity radio galaxies: B2 0258+35

Murthy, Suma,   Morganti, Raffaella,   Oosterloo, Tom,   Schulz, Robert,   Mukherjee, Dipanjan,   Wagner, Alexander Y.
September 2019  

Clumpy galaxies in cosmological simulations: the effect of ISM model

Inoue, Shigeki,   Yoshida, Naoki
September 2019   Monthly Notices of the Royal Astronomical Society

H$_2$ Ortho-Para Spin Conversion on Inhomogeneous Grain Surfaces

Furuya, Kenji,   Aikawa, Yuri,   Hama, Tetsuya,   Watanabe, Naoki
September 2019   The Astrophysical Journal

Radiative properties of the first galaxies: rapid transition between UV and infrared bright phases

Arata, Shohei,   Yajima, Hidenobu,   Nagamine, Kentaro,   Li, Yuexing,   Khochfar, Sadegh
September 2019   Monthly Notices of the Royal Astronomical Society

Magnetohydrodynamic simulation code CANS+: Assessments and applications

Matsumoto, Yosuke,   Asahina, Yuta,   Kudoh, Yuki,   Kawashima, Tomohisa,   Matsumoto, Jin,   Takahashi, Hiroyuki R.
August 2019   Publications of the Astronomical Society of Japan

On the dynamics and survival of fractal clouds in galactic winds

Banda-Barragán, W.~E.,   Zertuche, F.~J.,   Federrath, C.,   Garcı́a Del Valle, J.,   Brüggen, M.,   Wagner, A.~Y.
July 2019   Monthly Notices of the Royal Astronomical Society

Jets blowing bubbles in the young radio galaxy 4C 31.04

Zovaro, Henry R.~M.,   Sharp, Robert,   Nesvadba, Nicole P.~H.,   Bicknell, Geoffrey V.,   Mukherjee, Dipanjan,   Wagner, Alexand er Y.
April 2019   Monthly Notices of the Royal Astronomical Society

Osaka feedback model: isolated disc galaxy simulations

Shimizu, Ikkoh,   Todoroki, Keita,   Yajima, Hidenobu,   Nagamine, Kentaro
April 2019   Monthly Notices of the Royal Astronomical Society