Takuma Izumi
A5000231052- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Spectroscopy and Laser Applications
- Superconducting and THz Device Technology
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Calibration and Measurement Techniques
- Molecular Spectroscopy and Structure
- Photocathodes and Microchannel Plates
- Plant Water Relations and Carbon Dynamics
- Thermal Radiation and Cooling Technologies
- Hepatitis B Virus Studies
- Superconducting Materials and Applications
- Polymer crystallization and properties
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Thermodynamic properties of mixtures
- Advanced Sensor Technologies Research
Matsuyama Red Cross Hospital
2023-2025
National Astronomical Observatory of Japan
2015-2024
The Graduate University for Advanced Studies, SOKENDAI
2019-2024
National Institutes of Natural Sciences
2017-2024
Kagoshima University
2018-2024
Tokyo Metropolitan University
2023
Nippon Soken (Japan)
2023
High Energy Accelerator Research Organization
2018
Doshisha University
2018
Subaru (Japan)
2017
We report the source size distribution, as measured by ALMA millimetric continuum imaging, of a sample 13 AzTEC-selected submillimeter galaxies (SMGs) at –6. Their infrared luminosities and star formation rates (SFRs) are 2– ∼200–600 yr−1, respectively. The sizes these SMGs range from 010 to 038, with median 020 (FWHM), corresponding circularized effective radius () kpc, comparable typical stellar component in compact quiescent (cQGs)— kpc. surface SFR density our is yr−1 kpc−2, that seen...
Abstract We present deep near-infrared spectroscopy of six quasars at 6.1 ≤ z 6.7 with Very Large Telescope/X-Shooter and Gemini-N/GNIRS. Our objects, originally discovered through a wide-field optical survey the Hyper Suprime-Cam (HSC) Subaru Strategic Program (HSC-SSP), have lowest luminosities (−25.5 mag M 1450 −23.1 mag) > 5.8 measured black hole (BH) masses. From single-epoch mass measurements based on Mg ii λ 2798, we find wide range in BH masses, from = 10 7.6 to 9.3 ⊙ . The...
We report the results of 15 × 3' mapping at 1.1 mm with Atacama Large Millimeter/submillimeter Array toward central region z = 3.09 SSA22 protocluster. By combining our source catalog archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) flux densities, S1.1 0.7–6.4 mJy (LIR ∼ 1012.1–1013.1 L⊙) are 3.08–3.10. Not only these SMGs members protocluster, but they in fact reside within node junction 50 Mpc scale filamentary three-dimensional structure traced by Lyα...
We report discovery of 41 new high-z quasars and luminous galaxies, which were spectroscopically identified at 5.7 < z 6.9. This is the fourth in a series papers from Subaru High-z Exploration Low-Luminosity Quasars (SHELLQs) project, based on deep multi-band imaging data collected by Hyper Suprime-Cam (HSC) Strategic Program survey. selected photometric candidates Bayesian probabilistic algorithm, then carried out follow-up spectroscopy with Gran Telescopio Canarias Telescope. Combined...
We used the Atacama Large Millimeter/Submillimeter Array (ALMA) to map CO(3-2) and [CI](1-0) lines, as well their underlying continuum emission, from central $\sim 200$ pc region of Circinus galaxy that hosts nearest type 2 Seyfert-class active galactic nucleus (AGN), with a spatial resolution 6-15$ pc. The lines continuum-emitting regions consist circumnuclear disk (CND; 74 $\times$ 34 pc) spiral arms. distribution emission revealed temperature-dependent dust geometry possibly polar...
Abstract We report the discovery of 28 quasars and 7 luminous galaxies at 5.7 ≤ z 7.0. This is tenth in a series papers from Subaru High- Exploration Low-Luminosity Quasars (SHELLQs) project, which exploits deep multiband imaging data produced by Hyper Suprime-Cam (HSC) Strategic Program survey. The total number spectroscopically identified objects SHELLQs has now grown to 93 high- quasars, 31 galaxies, 16 [O iii ] emitters ∼ 0.8, 65 Galactic cool dwarfs (low-mass stars brown dwarfs). These...
We present the first results of Galaxy Activity, Torus and Outflow Survey (GATOS), a project aimed at understanding properties dusty molecular tori their connection to host galaxy in nearby Seyfert galaxies. Our expands range AGN luminosities Eddington ratios covered by previous surveys Seyferts conducted ALMA allows us study gas feeding feedback cycle combined sample 19 Seyferts. used obtain new images emission dust using CO(3-2) HCO+(4-3) lines as well underlying continuum 870 microns with...
Abstract We present ALMA [C ii] line and far-infrared (FIR) continuum observations of three $z \gt 6$ low-luminosity quasars ($M_{\rm 1450} -25$ mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The was detected in all targets with luminosities $(2.4\mbox{--}9.5) \times 10^8\, L_{\odot }$, about one order magnitude smaller than optically luminous \lesssim quasars. FIR range from $\lt 9 10^{10}\, }$ (3 $\sigma$ limit) to ${\sim } 2 10^{12}\, indicating a wide star formation rates...
We present ALMA [CII] 158 $\mu$m line and underlying far-infrared (FIR) continuum emission observations ($0''.70 \times 0''.56$ resolution) toward HSC J124353.93$+$010038.5 (J1243$+$0100) at $z = 7.07$, the only low-luminosity ($M_{\rm 1450} > -25$ mag) quasar currently known 7$. The FIR is bright (1.52 mJy) resolved with a total luminosity of $L_{\rm FIR} 3.5 10^{12}~L_\odot$. spatially extended component responsible for $\sim 40\%$ emission. area-integrated spectrum shows broad wing (${\rm...
Polycyclic Aromatic Hydrocarbons (PAHs) are carbon-based molecules that ubiquitous in a variety of astrophysical objects and environments. In this work, we use JWST/MIRI MRS spectroscopy three Seyferts to compare their nuclear PAH emission with star-forming regions. This study represents the first its kind using sub-arcsecond angular resolution data local luminous (Lbol>10^44.46 erg/s) on wide wavelength coverage (4.9-28.1 micron). We present an analysis properties by comparing observed...
Abstract We present the quasar luminosity function (LF) at z = 7, measured with 35 spectroscopically confirmed quasars 6.55 < 7.15. The sample of 22 from Subaru High- Exploration Low-Luminosity Quasars (SHELLQs) project, combined 13 brighter in literature, covers an unprecedentedly wide range rest-frame ultraviolet magnitudes over −28 M 1450 −23. found that binned LF flattens significantly toward faint end populated by SHELLQs quasars. A maximum likelihood fit to a double power-law model...
Abstract We present the first 100 pc scale view of dense molecular gas in central ∼1.3 kpc type-1 Seyfert NGC 1097, traced by HCN (J = 4–3) and HCO+ lines afforded with ALMA band 7. This galaxy shows significant enhancement respect to CO low-J transitions, which seems be a common characteristic AGN environments. Using data, we consider characteristics around this AGN, search for mechanism enhancement. find high line ratio nucleus. The upper limit brightness temperature (v 2 11f , J is 0.08,...
ABSTRACT Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4–3)/HCO + (4–3) and/or HCN(4–3)/CS(7–6) integrated intensity ratios in circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample is significantly increased our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool...
The nearby Sy 1 galaxy NGC 1097 represents an ideal laboratory to explore the molecular chemistry in presence and surroundings of active galactic nucleus. Exploring distribution different species allows us understand physical processes affecting ISM both AGN vicinity as well outer star forming ring. We carried out 3 mm ALMA observations HCN, HCO+, CCH, CS, HNCO, SiO, HC3N, SO 13C isotopologues. All were imaged over central 2 kpc (~30") at a resolution ~2.2"x1.5 (150 pc x 100 pc). HCO+ CS...
We present new measurements of the quasar luminosity function (LF) at $z \sim 6$, over an unprecedentedly wide range rest-frame ultraviolet $M_{1450}$ from $-30$ to $-22$ mag. This is fifth in a series publications Subaru High-$z$ Exploration Low-Luminosity Quasars (SHELLQs) project, which exploits deep multi-band imaging data produced by Hyper Suprime-Cam (HSC) Strategic Program survey. The LF was calculated with complete sample 110 quasars $5.7 \le z 6.5$, includes 48 SHELLQs discovered...
We present spectroscopic identification of 32 new quasars and luminous galaxies discovered at 5.7 < z 6.8. This is the second in a series papers presenting results Subaru High-z Exploration Low-Luminosity Quasars (SHELLQs) project, which exploits deep multi-band imaging data produced by Hyper Suprime-Cam (HSC) Strategic Program survey. The photometric candidates were selected Bayesian probabilistic algorithm, then observed with spectrographs on Gran Telescopio Canarias Telescope. Combined...
We present the results of our ALMA Cycle 4 high-spatial-resolution (0.04-0.07") observations, at HCN J=3-2 and HCO+ lines, nucleus NGC 1068, nearby prototypical type 2 active galactic (AGN). Our previous observations identified compact emission these lines putative location torus around a mass-accreting supermassive black hole. now report that we have detected rotation this emission, with eastern western sides being redshifted blueshifted, respectively. Unlike previously reported CO J=6-5...
ALMA observations have revealed nuclear dusty molecular disks or tori with characteristic sizes 15−40 pc in the few Seyferts and low -luminosity AGN that been studied so far. These structures are generally decoupled both morphologically kinematically from host galaxy disk. We present of CO(2–1) CO(3–2) gas transitions associated (sub-) millimeter continua nearby Seyfert 1.5 NGC 3227 angular resolutions 0.085 − 0.21″ (7–15 pc). On large scales, cold shows circular motions as well streaming on...
We used the Atacama Large Millimeter/submillimeter Array (ALMA), covering a nearly contiguous 289 GHz frequency range between 84.2 and 373.2 GHz, to image continuum spectral line emission at 1.6\arcsec ($\sim 28$ pc) resolution down sensitivity of $30-50$ mK. This article describes ALMA Comprehensive High-resolution Extragalactic Molecular Inventory (ALCHEMI) Program. focus on analysis spectra extracted from $15''$ ($\sim255$ Compact data. model molecular assuming local thermodynamic...
Abstract We present the spectroscopic discovery of 69 quasars at 5.8 < z 7.0, drawn from Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) imaging survey data. This is 16th publication High- Exploration Low-Luminosity Quasars (SHELLQs) project, and it completes identification all but faintest candidates (i.e., i -band dropouts with AB 24 y detections, 24) Bayesian quasar probability <?CDATA ${P}_{Q}^{B}\gt 0.1$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Abstract To understand the origin of nuclear (≲100 pc) millimeter-wave (mm-wave) continuum emission in active galactic nuclei (AGNs), we systematically analyzed subarcsecond resolution Band-6 (211–275 GHz) Atacama Large Millimeter/submillimeter Array data 98 nearby AGNs ( z < 0.05) from 70 month Swift/BAT catalog. The sample, almost unbiased for obscured systems, provides largest number to date with high mm-wave spatial sampling (∼1–200 pc), and spans broad ranges 14–150 keV luminosity {...
The ionisation cones of NGC 5728 have a deficit molecular gas based on millimetre observations CO (2-1) emission. Although photoionisation from the active nucleus may lead to suppression this transition, warm can still be present. We report detection eight mid-infrared rotational H 2 lines throughout central kiloparsec, including cones, using integral field spectroscopic with JWST/MIRI MRS. line ratios, characteristic power-law temperature distribution, indicate that is warmest where it...
We present our ALMA Cycle 4 measurements of the [CII] emission line and underlying far-infrared (FIR) continuum from four optically low-luminosity ($M_{\rm 1450} > -25$) quasars at $z \gtrsim 6$ discovered by Subaru Hyper Suprime Cam (HSC) survey. The FIR luminosities lie in ranges $L_{\rm [CII]} = (3.8-10.2) \times 10^8~L_\odot$ FIR} (1.2-2.0) 10^{11}~L_\odot$, which are least one order magnitude smaller than those optically-luminous 6$. estimate star formation rates (SFR) targets as...