Achievements & Publications

Systematic two-dimensional radiation-hydrodynamic simulations of super-Eddington accretion flow and outflow: Comparison with the slim disk model

Image

Kitaki, Takaaki,   Mineshige, Shin,   Ohsuga, Ken,   Kawashima, Tomohisa

To what extent can the one-dimensional slim disk model reproduce the multi-dimensional results of global radiation-hydrodynamic simulations of super-Eddington accretion? With this question in mind, we perform a systematic simulation study of accretion flow onto a non-spinning black hole for a variety of black hole masses of (10-10$^7$) M$_☉$ and...

Probing the high-redshift universe with SPICA: Toward the epoch of reionisation and beyond

Image

Egami, E.,   Gallerani, S.,   Schneider, R.,   Pallottini, A.,   Vallini, L.,   Sobacchi, E.

With the recent discovery of a dozen dusty star-forming galaxies and around 30 quasars at z > 5 that are hyper-luminous in the infrared (\ensuremathμ L $_IR$ > 10$^13$ L$_☉$, where \ensuremathμ is a lensing magnification factor), the possibility has opened up for SPICA, the proposed ESA M5 mid-/far-infrared mission,...

A Cool Core Disturbed: Observational Evidence for the Coexistence of Subsonic Sloshing Gas and Stripped Shock-heated Gas around the Core of RX J1347.5-1145

Image

Ueda, Shutaro,   Kitayama, Tetsu,   Oguri, Masamune,   Komatsu, Eiichiro,   Akahori, Takuya,   Iono, Daisuke

RX J1347.5-1145 (z = 0.451) is one of the most luminous X-ray galaxy clusters; it hosts a prominent cool core and exhibits a signature of a major merger. We present the first direct observational evidence for the subsonic nature of the sloshing motion of the cool core. We find that...

Linking interstellar and cometary O$_2$: a deep search for $^16$O$^18$O in the solar-type protostar IRAS 16293-2422

Image

Taquet, V.,   van Dishoeck, E.~F.,   Swayne, M.,   Harsono, D.,   Jørgensen, J.~K.,   Maud, L.

Recent measurements carried out at comet 67P/Churyumov-Gerasimenko (67P) with the Rosetta probe revealed that molecular oxygen, O$_2$, is the fourth most abundant molecule in comets. Models show that O$_2$ is likely of primordial nature, coming from the interstellar cloud from which our solar system was formed. However, gaseous O$_2$ is...

Relativistic jet feedback - III. Feedback on gas discs

Image

Mukherjee, Dipanjan,   Bicknell, Geoffrey V.,   Wagner, Alexand er Y.,   Sutherland, Ralph S.,   Silk, Joseph

We study the interactions of a relativistic jet with a dense turbulent gaseous disc of radius ̃2 kpc. We have performed a suite of simulations with different mean density, jet power, and orientation. Our results show that: (A) The relativistic jet couples strongly with the gas in the inner kpc,...

Extreme gaseous outflows in radio-loud narrow-line Seyfert 1 galaxies

Image

Komossa, S.,   Xu, D.~W.,   Wagner, A.~Y.

We present four radio-loud narrow-line Seyfert 1 (NLS1) galaxies with extreme emission-line shifts, indicating radial outflow velocities of the ionized gas of up to 2450 km s$^-1$, above the escape velocity of the host galaxies. The forbidden lines show strong broadening, up to 2270 km s$^-1$. An ionization stratification (higher...

Depletion of $^15$N in the center of L1544: Early transition from atomic to molecular nitrogen?

Image

Furuya, K.,   Watanabe, Y.,   Sakai, T.,   Aikawa, Y.,   Yamamoto, S.

We performed sensitive observations of the N$^15$ND$^+$(1-0) and $^15$NND$^+$(1-0) lines toward the prestellar core L1544 using the IRAM 30 m telescope. The lines are not detected down to 3\ensuremathσ levels in 0.2 km s$^-$1 channels of 6 mK. The non-detection provides the lower limit of the $^14$N/$^15$N ratio for N$_2$D$^+$...

SILVERRUSH. VI. A simulation of Ly\ensuremathα emitters in the reionization epoch and a comparison with Subaru Hyper Suprime-Cam survey early data

Image

Inoue, Akio K.,   Hasegawa, Kenji,   Ishiyama, Tomoaki,   Yajima, Hidenobu,   Shimizu, Ikkoh,   Umemura, Masayuki

The survey of Lyman \ensuremathα emitters (LAEs) with the Subaru Hyper Suprime-Cam, called SILVERRUSH (Ouchi et al. 2018, PASJ, 70, S13), is producing massive data of LAEs at z \ensuremath\gtrsim 6. Here we present LAE simulations to compare the SILVERRUSH data. In 162$^3$ comoving Mpc$^3$ boxes, where numerical radiative transfer...

Tracing the atomic nitrogen abundance in star-forming regions with ammonia deuteration

Image

Furuya, Kenji,   Persson, Magnus V.

Partitioning of elemental nitrogen in star-forming regions is not well constrained. Most nitrogen is expected to be partitioned among atomic nitrogen (N I), molecular nitrogen (N_2), and icy N-bearing molecules, such as NH_3 and N_2. N I is not directly observable in the cold gas. In this paper, we propose...

AGN feedback compared: jets versus radiation

Image

Cielo, Salvatore,   Bieri, Rebekka,   Volonteri, Marta,   Wagner, Alexander Y.,   Dubois, Yohan

Feedback by active galactic nuclei (AGNs) is often divided into quasar and radio mode, powered by radiation or radio jets, respectively. Both are fundamental in galaxy evolution, especially in late-type galaxies, as shown by cosmological simulations and observations of jet-ISM (interstellar medium) interactions in these systems. We compare AGN feedback...

Magnetohydrodynamic Simulations of a Plunging Black Hole into a Molecular Cloud

Image

Nomura, Mariko,   Oka, Tomoharu,   Yamada, Masaya,   Takekawa, Shunya,   Ohsuga, Ken,   Takahashi, Hiroyuki R.

Using two-dimensional magnetohydrodynamic simulations, we investigated the gas dynamics around a black hole (BH) plunging into a molecular cloud. In these calculations, we assumed a parallel- magnetic-field layer in the cloud. The size of the accelerated region is far larger than the Bondi-Hoyle-Lyttleton radius, being approximately inversely proportional to the...

The jet-ISM interactions in IC 5063

Image

Mukherjee, Dipanjan,   Wagner, Alexander Y.,   Bicknell, Geoffrey V.,   Morganti, Raffaella,   Oosterloo, Tom,   Nesvadba, Nicole

The interstellar medium of the radio galaxy IC 5063 is highly perturbed by an AGN jet expanding in the gaseous disc of the galaxy. We model this interaction with relativistic hydrodynamic simulations and multiphase initial conditions for the interstellar medium and compare the results with recent observations. As the jets...

SEURAT: SPH scheme extended with ultraviolet line radiative transfer

Image

Abe, Makito,   Suzuki, Hiroyuki,   Hasegawa, Kenji,   Semelin, Benoit,   Yajima, Hidenobu,   Umemura, Masayuki

We present a novel Lyman alpha (Ly \ensuremathα) radiative transfer code, SEURAT (SPH scheme Extended with Ultraviolet line RAdiative Transfer), where line scatterings are solved adaptively with the resolution of the smoothed particle hydrodynamics (SPH). The radiative transfer method implemented in SEURAT is based on a Monte Carlo algorithm in...

ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Complex Organic and Deuterated Molecules

Image

Sakai, Takeshi,   Yanagida, Takahiro,   Furuya, Kenji,   Aikawa, Yuri,   Sanhueza, Patricio,   Sakai, Nami

We have observed complex organic molecules (COMs) and deuterated species toward a hot core/corino (HC) associated with the infrared dark cloud clump G34.43+00.24 MM3 with the Atacama Large Millimeter/submillimeter Array. We have detected six normal-COMs (CH$_3$OH, CH$_3$CHO, CH$_3$CH$_2$CN, CH$_3$OCH$_3$, HCOOCH$_3$, and NH$_2$CHO), one deuterated-COM (CH$_2$DCN), and two deuterated fundamental molecules...

MAGI: many-component galaxy initializer

Image

Miki, Yohei,   Umemura, Masayuki

Providing initial conditions is an essential procedure for numerical simulations of galaxies. The initial conditions for idealized individual galaxies in N-body simulations should resemble observed galaxies and be dynamically stable for time-scales much longer than their characteristic dynamical times. However, generating a galaxy model ab initio as a system in...

Depletion of Heavy Nitrogen in the Cold Gas of Star-forming Regions

Image

Furuya, Kenji,   Aikawa, Yuri

We investigate nitrogen-isotope fractionation in forming and evolving molecular clouds using gas-ice astrochemical simulations. We find that the bulk gas can become depleted in heavy nitrogen ($^15$N) due to the formation of $^15$N-enriched ices. Around the chemical transition from atomic nitrogen to N$_2$, N$^15$N is selectively photodissociated, which results in...

Relativistic jet feedback - II. Relationship to gigahertz peak spectrum and compact steep spectrum radio galaxies

Image

Bicknell, Geoffrey V.,   Mukherjee, Dipanjan,   Wagner, Alexand er Y.,   Sutherland, Ralph S.,   Nesvadba, Nicole P.~H.

We propose that Gigahertz Peak Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources are the signposts of relativistic jet feedback in evolving galaxies. Our simulations of relativistic jets interacting with a warm, inhomogeneous medium, utilizing cloud densities and velocity dispersions in the range derived from optical observations, show that...

Image

Systematic two-dimensional radiation-hydrodynamic simulations of super-Eddington accretion flow and outflow: Comparison with the slim disk model

Kitaki, Takaaki,   Mineshige, Shin,   Ohsuga, Ken,   Kawashima, Tomohisa

To what extent can the one-dimensional slim disk model reproduce the multi-dimensional results of global radiation-hydrodynamic simulations of super-Eddington accretion? With this question in mind, we perform a systematic simulation study of accretion flow onto a non-spinning black hole for a variety of black hole masses of (10-10$^7$) M$_☉$ and...

December 2018   Publications of the Astronomical Society of Japan
Image

Probing the high-redshift universe with SPICA: Toward the epoch of reionisation and beyond

Egami, E.,   Gallerani, S.,   Schneider, R.,   Pallottini, A.,   Vallini, L.,   Sobacchi, E.

With the recent discovery of a dozen dusty star-forming galaxies and around 30 quasars at z > 5 that are hyper-luminous in the infrared (\ensuremathμ L $_IR$ > 10$^13$ L$_☉$, where \ensuremathμ is a lensing magnification factor), the possibility has opened up for SPICA, the proposed ESA M5 mid-/far-infrared mission,...

December 2018   Publications of the Astronomical Society of Australia
Image

A Cool Core Disturbed: Observational Evidence for the Coexistence of Subsonic Sloshing Gas and Stripped Shock-heated Gas around the Core of RX J1347.5-1145

Ueda, Shutaro,   Kitayama, Tetsu,   Oguri, Masamune,   Komatsu, Eiichiro,   Akahori, Takuya,   Iono, Daisuke

RX J1347.5-1145 (z = 0.451) is one of the most luminous X-ray galaxy clusters; it hosts a prominent cool core and exhibits a signature of a major merger. We present the first direct observational evidence for the subsonic nature of the sloshing motion of the cool core. We find that...

October 2018   The Astrophysical Journal
Image

Linking interstellar and cometary O$_2$: a deep search for $^16$O$^18$O in the solar-type protostar IRAS 16293-2422

Taquet, V.,   van Dishoeck, E.~F.,   Swayne, M.,   Harsono, D.,   Jørgensen, J.~K.,   Maud, L.

Recent measurements carried out at comet 67P/Churyumov-Gerasimenko (67P) with the Rosetta probe revealed that molecular oxygen, O$_2$, is the fourth most abundant molecule in comets. Models show that O$_2$ is likely of primordial nature, coming from the interstellar cloud from which our solar system was formed. However, gaseous O$_2$ is...

October 2018  
Image

Relativistic jet feedback - III. Feedback on gas discs

Mukherjee, Dipanjan,   Bicknell, Geoffrey V.,   Wagner, Alexand er Y.,   Sutherland, Ralph S.,   Silk, Joseph

We study the interactions of a relativistic jet with a dense turbulent gaseous disc of radius ̃2 kpc. We have performed a suite of simulations with different mean density, jet power, and orientation. Our results show that: (A) The relativistic jet couples strongly with the gas in the inner kpc,...

October 2018   Monthly Notices of the Royal Astronomical Society
Image

Extreme gaseous outflows in radio-loud narrow-line Seyfert 1 galaxies

Komossa, S.,   Xu, D.~W.,   Wagner, A.~Y.

We present four radio-loud narrow-line Seyfert 1 (NLS1) galaxies with extreme emission-line shifts, indicating radial outflow velocities of the ionized gas of up to 2450 km s$^-1$, above the escape velocity of the host galaxies. The forbidden lines show strong broadening, up to 2270 km s$^-1$. An ionization stratification (higher...

July 2018   Monthly Notices of the Royal Astronomical Society
Image

Depletion of $^15$N in the center of L1544: Early transition from atomic to molecular nitrogen?

Furuya, K.,   Watanabe, Y.,   Sakai, T.,   Aikawa, Y.,   Yamamoto, S.

We performed sensitive observations of the N$^15$ND$^+$(1-0) and $^15$NND$^+$(1-0) lines toward the prestellar core L1544 using the IRAM 30 m telescope. The lines are not detected down to 3\ensuremathσ levels in 0.2 km s$^-$1 channels of 6 mK. The non-detection provides the lower limit of the $^14$N/$^15$N ratio for N$_2$D$^+$...

July 2018  
Image

SILVERRUSH. VI. A simulation of Ly\ensuremathα emitters in the reionization epoch and a comparison with Subaru Hyper Suprime-Cam survey early data

Inoue, Akio K.,   Hasegawa, Kenji,   Ishiyama, Tomoaki,   Yajima, Hidenobu,   Shimizu, Ikkoh,   Umemura, Masayuki

The survey of Lyman \ensuremathα emitters (LAEs) with the Subaru Hyper Suprime-Cam, called SILVERRUSH (Ouchi et al. 2018, PASJ, 70, S13), is producing massive data of LAEs at z \ensuremath\gtrsim 6. Here we present LAE simulations to compare the SILVERRUSH data. In 162$^3$ comoving Mpc$^3$ boxes, where numerical radiative transfer...

June 2018   Publications of the Astronomical Society of Japan
Image

Tracing the atomic nitrogen abundance in star-forming regions with ammonia deuteration

Furuya, Kenji,   Persson, Magnus V.

Partitioning of elemental nitrogen in star-forming regions is not well constrained. Most nitrogen is expected to be partitioned among atomic nitrogen (N I), molecular nitrogen (N_2), and icy N-bearing molecules, such as NH_3 and N_2. N I is not directly observable in the cold gas. In this paper, we propose...

June 2018   Monthly Notices of the Royal Astronomical Society
Image

AGN feedback compared: jets versus radiation

Cielo, Salvatore,   Bieri, Rebekka,   Volonteri, Marta,   Wagner, Alexander Y.,   Dubois, Yohan

Feedback by active galactic nuclei (AGNs) is often divided into quasar and radio mode, powered by radiation or radio jets, respectively. Both are fundamental in galaxy evolution, especially in late-type galaxies, as shown by cosmological simulations and observations of jet-ISM (interstellar medium) interactions in these systems. We compare AGN feedback...

June 2018   Monthly Notices of the Royal Astronomical Society
Image

Magnetohydrodynamic Simulations of a Plunging Black Hole into a Molecular Cloud

Nomura, Mariko,   Oka, Tomoharu,   Yamada, Masaya,   Takekawa, Shunya,   Ohsuga, Ken,   Takahashi, Hiroyuki R.

Using two-dimensional magnetohydrodynamic simulations, we investigated the gas dynamics around a black hole (BH) plunging into a molecular cloud. In these calculations, we assumed a parallel- magnetic-field layer in the cloud. The size of the accelerated region is far larger than the Bondi-Hoyle-Lyttleton radius, being approximately inversely proportional to the...

May 2018   The Astrophysical Journal
Image

The jet-ISM interactions in IC 5063

Mukherjee, Dipanjan,   Wagner, Alexander Y.,   Bicknell, Geoffrey V.,   Morganti, Raffaella,   Oosterloo, Tom,   Nesvadba, Nicole

The interstellar medium of the radio galaxy IC 5063 is highly perturbed by an AGN jet expanding in the gaseous disc of the galaxy. We model this interaction with relativistic hydrodynamic simulations and multiphase initial conditions for the interstellar medium and compare the results with recent observations. As the jets...

May 2018   Monthly Notices of the Royal Astronomical Society
Image

SEURAT: SPH scheme extended with ultraviolet line radiative transfer

Abe, Makito,   Suzuki, Hiroyuki,   Hasegawa, Kenji,   Semelin, Benoit,   Yajima, Hidenobu,   Umemura, Masayuki

We present a novel Lyman alpha (Ly \ensuremathα) radiative transfer code, SEURAT (SPH scheme Extended with Ultraviolet line RAdiative Transfer), where line scatterings are solved adaptively with the resolution of the smoothed particle hydrodynamics (SPH). The radiative transfer method implemented in SEURAT is based on a Monte Carlo algorithm in...

May 2018   Monthly Notices of the Royal Astronomical Society
Image

ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Complex Organic and Deuterated Molecules

Sakai, Takeshi,   Yanagida, Takahiro,   Furuya, Kenji,   Aikawa, Yuri,   Sanhueza, Patricio,   Sakai, Nami

We have observed complex organic molecules (COMs) and deuterated species toward a hot core/corino (HC) associated with the infrared dark cloud clump G34.43+00.24 MM3 with the Atacama Large Millimeter/submillimeter Array. We have detected six normal-COMs (CH$_3$OH, CH$_3$CHO, CH$_3$CH$_2$CN, CH$_3$OCH$_3$, HCOOCH$_3$, and NH$_2$CHO), one deuterated-COM (CH$_2$DCN), and two deuterated fundamental molecules...

April 2018   The Astrophysical Journal
Image

MAGI: many-component galaxy initializer

Miki, Yohei,   Umemura, Masayuki

Providing initial conditions is an essential procedure for numerical simulations of galaxies. The initial conditions for idealized individual galaxies in N-body simulations should resemble observed galaxies and be dynamically stable for time-scales much longer than their characteristic dynamical times. However, generating a galaxy model ab initio as a system in...

April 2018   Monthly Notices of the Royal Astronomical Society
Image

Depletion of Heavy Nitrogen in the Cold Gas of Star-forming Regions

Furuya, Kenji,   Aikawa, Yuri

We investigate nitrogen-isotope fractionation in forming and evolving molecular clouds using gas-ice astrochemical simulations. We find that the bulk gas can become depleted in heavy nitrogen ($^15$N) due to the formation of $^15$N-enriched ices. Around the chemical transition from atomic nitrogen to N$_2$, N$^15$N is selectively photodissociated, which results in...

April 2018   The Astrophysical Journal
Image

Relativistic jet feedback - II. Relationship to gigahertz peak spectrum and compact steep spectrum radio galaxies

Bicknell, Geoffrey V.,   Mukherjee, Dipanjan,   Wagner, Alexand er Y.,   Sutherland, Ralph S.,   Nesvadba, Nicole P.~H.

We propose that Gigahertz Peak Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources are the signposts of relativistic jet feedback in evolving galaxies. Our simulations of relativistic jets interacting with a warm, inhomogeneous medium, utilizing cloud densities and velocity dispersions in the range derived from optical observations, show that...

April 2018   Monthly Notices of the Royal Astronomical Society

Systematic two-dimensional radiation-hydrodynamic simulations of super-Eddington accretion flow and outflow: Comparison with the slim disk model

Kitaki, Takaaki,   Mineshige, Shin,   Ohsuga, Ken,   Kawashima, Tomohisa
December 2018   Publications of the Astronomical Society of Japan

Probing the high-redshift universe with SPICA: Toward the epoch of reionisation and beyond

Egami, E.,   Gallerani, S.,   Schneider, R.,   Pallottini, A.,   Vallini, L.,   Sobacchi, E.
December 2018   Publications of the Astronomical Society of Australia

A Cool Core Disturbed: Observational Evidence for the Coexistence of Subsonic Sloshing Gas and Stripped Shock-heated Gas around the Core of RX J1347.5-1145

Ueda, Shutaro,   Kitayama, Tetsu,   Oguri, Masamune,   Komatsu, Eiichiro,   Akahori, Takuya,   Iono, Daisuke
October 2018   The Astrophysical Journal

Linking interstellar and cometary O$_2$: a deep search for $^16$O$^18$O in the solar-type protostar IRAS 16293-2422

Taquet, V.,   van Dishoeck, E.~F.,   Swayne, M.,   Harsono, D.,   Jørgensen, J.~K.,   Maud, L.
October 2018  

Relativistic jet feedback - III. Feedback on gas discs

Mukherjee, Dipanjan,   Bicknell, Geoffrey V.,   Wagner, Alexand er Y.,   Sutherland, Ralph S.,   Silk, Joseph
October 2018   Monthly Notices of the Royal Astronomical Society

Extreme gaseous outflows in radio-loud narrow-line Seyfert 1 galaxies

Komossa, S.,   Xu, D.~W.,   Wagner, A.~Y.
July 2018   Monthly Notices of the Royal Astronomical Society

Depletion of $^15$N in the center of L1544: Early transition from atomic to molecular nitrogen?

Furuya, K.,   Watanabe, Y.,   Sakai, T.,   Aikawa, Y.,   Yamamoto, S.
July 2018  

SILVERRUSH. VI. A simulation of Ly\ensuremathα emitters in the reionization epoch and a comparison with Subaru Hyper Suprime-Cam survey early data

Inoue, Akio K.,   Hasegawa, Kenji,   Ishiyama, Tomoaki,   Yajima, Hidenobu,   Shimizu, Ikkoh,   Umemura, Masayuki
June 2018   Publications of the Astronomical Society of Japan

Tracing the atomic nitrogen abundance in star-forming regions with ammonia deuteration

Furuya, Kenji,   Persson, Magnus V.
June 2018   Monthly Notices of the Royal Astronomical Society

AGN feedback compared: jets versus radiation

Cielo, Salvatore,   Bieri, Rebekka,   Volonteri, Marta,   Wagner, Alexander Y.,   Dubois, Yohan
June 2018   Monthly Notices of the Royal Astronomical Society

Magnetohydrodynamic Simulations of a Plunging Black Hole into a Molecular Cloud

Nomura, Mariko,   Oka, Tomoharu,   Yamada, Masaya,   Takekawa, Shunya,   Ohsuga, Ken,   Takahashi, Hiroyuki R.
May 2018   The Astrophysical Journal

The jet-ISM interactions in IC 5063

Mukherjee, Dipanjan,   Wagner, Alexander Y.,   Bicknell, Geoffrey V.,   Morganti, Raffaella,   Oosterloo, Tom,   Nesvadba, Nicole
May 2018   Monthly Notices of the Royal Astronomical Society

SEURAT: SPH scheme extended with ultraviolet line radiative transfer

Abe, Makito,   Suzuki, Hiroyuki,   Hasegawa, Kenji,   Semelin, Benoit,   Yajima, Hidenobu,   Umemura, Masayuki
May 2018   Monthly Notices of the Royal Astronomical Society

ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Complex Organic and Deuterated Molecules

Sakai, Takeshi,   Yanagida, Takahiro,   Furuya, Kenji,   Aikawa, Yuri,   Sanhueza, Patricio,   Sakai, Nami
April 2018   The Astrophysical Journal

MAGI: many-component galaxy initializer

Miki, Yohei,   Umemura, Masayuki
April 2018   Monthly Notices of the Royal Astronomical Society

Depletion of Heavy Nitrogen in the Cold Gas of Star-forming Regions

Furuya, Kenji,   Aikawa, Yuri
April 2018   The Astrophysical Journal

Relativistic jet feedback - II. Relationship to gigahertz peak spectrum and compact steep spectrum radio galaxies

Bicknell, Geoffrey V.,   Mukherjee, Dipanjan,   Wagner, Alexand er Y.,   Sutherland, Ralph S.,   Nesvadba, Nicole P.~H.
April 2018   Monthly Notices of the Royal Astronomical Society