A5025460496- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Remote Sensing in Agriculture
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Advanced Vision and Imaging
- CCD and CMOS Imaging Sensors
- Scientific Research and Discoveries
- Spectroscopy and Laser Applications
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Advanced Chemical Physics Studies
- Inorganic Fluorides and Related Compounds
- Cosmology and Gravitation Theories
- Photoreceptor and optogenetics research
- Astro and Planetary Science
- Phase Equilibria and Thermodynamics
- Advanced Fluorescence Microscopy Techniques
- Advanced Glycation End Products research
- Anomaly Detection Techniques and Applications
- Remote Sensing and LiDAR Applications
Waseda University
2023-2024
National Astronomical Observatory of Japan
2014-2023
National Institutes of Natural Sciences
2018-2023
The University of Tokyo
2021
Subaru (Japan)
2014-2020
University of California, Santa Cruz
2017-2018
The Graduate University for Advanced Studies, SOKENDAI
2012-2017
Abstract We report on the spectroscopic confirmation of a massive quiescent galaxy at z spec = 4.53 in COSMOS field. The object was first identified as with suppressed star formation phot ∼ 4.65 from COSMOS2020 catalog. follow-up spectroscopy Keck/MOSFIRE K band reveals faint [O ii ] emission and Balmer break, indicative evolved stellar populations. fit spectral energy distribution using photometry spectrum to infer physical properties. obtained mass is high ( M * 10 10.8 ⊙ ) current rate...
Abstract We report on discovery of a concentration massive quiescent galaxies located at z = 4. The is first identified using high-quality photometric redshifts based deep, multiband data in Subaru/XMM-Newton Deep Field. Follow-up near-infrared spectroscopic observations with MOSFIRE Keck confirm (∼10 11 M ⊙ ) galaxy 3.99. Our spectral energy distribution analyses reveal that the experienced an episode starburst about 500 Myr prior to observed epoch, followed by rapid quenching. Since its...
ABSTRACT As a considerable investment of time from various telescope facilities was dedicated toward studying the Spiderweb protocluster at z = 2.2, it so far remains one most extensively studied protocluster. We report here latest results in this field, adding new dimension to previous research on cluster formation high redshift. Previous studies have reported significant overdensity (δ ∼ 10) massive Hα (+ [N ii])-emitting galaxies 3700 comoving Mpc3. Many these were previously considered...
We present 0".2-resolution Atacama Large Millimeter/submillimeter Array observations at 870 um for 25 Halpha-seleced star-forming galaxies (SFGs) around the main-sequence z=2.2-2.5. detect significant continuum emission in 16 (64%) of these SFGs. The high-resolution maps reveal that dust is mostly radiated from a single region close to galaxy center. Exploiting visibility data taken over wide $uv$ distance range, we measure half-light radii rest-frame far-infrared best sample 12 massive with...
We present spatially resolved ALMA observations of the CO J=3-2 emission line in two massive galaxies at z=2.5 on star-forming main sequence. Both have compact dusty cores with effective radii Re=1.3 kpc and Re=1.2 870 um continuum emission. The spatial extent molecular gas is also Re=1.9 Re=2.3 kpc, but more extended than dust Interpreting observed position-velocity diagrams dynamical models, we find starburst to be rotation-dominated ratio maximum rotation velocity local dispersion...
We carried out deep H$\alpha$ narrowband imaging with 10 hours net integrations towards the young protocluster, USS1558$-$003 at $z=2.53$ Subaru Telescope. This system is composed of four dense groups massive local overdensities, traced by 107 emitters (HAEs) stellar masses and dust-corrected star formation rates down to $1\times10^8$ M$_\odot$ 3 M$_\odot$yr$^{-1}$, respectively. have investigated environmental dependence various physical properties within protocluster comparing...
Stars form in galaxies, from gas that has been accreted the intergalactic medium. Simulations have shown recycling of gas-the reaccretion was previously ejected a galaxy-could sustain star formation early Universe. We observe surrounding massive galaxy at redshift 2.3 and detect emission lines neutral hydrogen, helium, ionized carbon extend 100 kiloparsecs galaxy. The kinematics this circumgalactic is consistent with an inspiraling stream. abundance indicates had already enriched elements...
We present the results of near-infrared spectroscopy H$\alpha$ emitters (HAEs) associated with two protoclusters around radio galaxies (PKS1138-262 at $z$=2.2 and USS1558-003 $z$=2.5) Multi-Object Infrared Camera Spectrograph (MOIRCS) on Subaru telescope. Among HAE candidates constructed from our narrow-band imaging, we have confirmed membership 27 36 HAEs for respective protoclusters, a success rate 70 per cent observed targets. The large number spectroscopically members cluster has enabled...
This work presents the results from our near-infrared spectroscopy of narrow-band-selected Hα emitters (HAEs) in two rich overdensities (PKS 1138−262 at z = 2.2 and USS 1558−003 2.5) with Multi-Object Infrared Camera Spectrograph on Subaru telescope. These protoclusters are promising candidates for most massive class galaxy clusters seen today (Paper I). The confirmed HAEs > 2 show high excitation levels as characterized by much higher [O iii]/Hβ or iii]/Hα line ratios than those general...
In the redshift interval of 2 < z 3, physical conditions interstellar medium (ISM) in star-forming galaxies are likely to be different from those local Universe because lower gaseous metallicities, higher gas fractions, and star formation activities. fact, observations suggest that electron densities, ionization parameters, harder UV radiation fields common. this paper, based on spectra H α-selected at = 2.5 taken with Multi-Object Spectrometer for InfraRed Exploration Keck-1 telescope, we...
Abstract We present the results from ALMA CO(3–2) observations of 66 Hα-selected galaxies in three protoclusters around radio galaxies: PKS 1138−262 ($z$ = 2.16), USS 1558−003 2.53), and 4C 23.56 2.49). The pointing areas have an overdensity ∼100 compared to mean surface number density field environments. detect CO emission line 16 star-forming galaxies, including six previously published measure molecular gas mass. In stellar mass range 10.5 &lt; log (Mstar/M⊙) 11.0, protocluster larger...
This paper is the second in a series presenting results of our deep H$\alpha$-line survey towards protoclusters at $z>2$, based on narrow-band imaging with Subaru Telescope. work investigates massive galaxies protocluster region associated radio galaxy (PKS 1138$-$262), Spiderweb galaxy, $z=2.2$. Our 0.5 mag deeper than previous surveys collects total 68 H$\alpha$ emitters (HAE). 17 out are newly discovered members. First, very high characteristic stellar mass M$_\star^\ast=10^{11.73}$...
We report two secure ($z=3.775, 4.012$) and one tentative ($z\approx3.767$) spectroscopic confirmations of massive quiescent galaxies through $K$-band observations with Keck/MOSFIRE VLT/X-Shooter. The stellar continuum emission, the absence strong nebular emission lines lack significant far-infrared detections confirm passive nature these objects, disfavoring alternative solution low-redshift dusty star-forming interlopers. derive masses $\mathrm{log}(M_{\star}/M_\odot)\sim11$ ongoing star...
ABSTRACT We use multi-object near-infrared spectroscopy with VLT/KMOS to investigate the role of environment in evolution ionized gas properties narrow-band-selected H α emitters (HAEs) Spiderweb protocluster at z = 2.16. Based on rest-frame optical emission lines, and [N ii]λ6584, we confirm cluster membership 39 our targets (i.e. 93 per cent success rate), measure their star formation rates (SFR), gas-phase oxygen abundances, effective radius. parametrize where reside using local global...
We present the morphological properties of 109 H\alpha-selected galaxies at z>2 in SXDF-UDS-CANDELS field. With high-resolution optical/near-infrared images obtained by Hubble Space Telescope, we identify giant clumps within H\alpha emitters (HAEs). find that least 41% our sample show clumpy structures underlying disks. The color gradient is commonly seen sense near galactic center tend to be redder than those outer regions. mid-infrared detection with red and spatial distribution emission...
Abstract We report a survey of molecular gas in galaxies the XMMXCS J2215.9–1738 cluster at z = 1.46. have detected emission lines from 17 within radius R 200 center, Band 3 data Atacama Large Millimeter/submillimeter Array, with coverage 93–95 GHz frequency and 2.33 arcmin 2 spatial direction. The are all identified as CO J 2–1 members by their redshifts colors optical near-infrared (NIR) counterparts. line luminosities reach down to K km s −1 pc . distribution detection CO(2–1) suggests...
Abstract We present molecular gas reservoirs of 18 galaxies associated with the XMMXCS J2215.9–1738 cluster at z = 1.46. From Band 7 and 3 data Atacama Large Millimeter/submillimeter Array, we detect dust continuum emission 870 μ m CO J 2–1 line from 8 17 member galaxies, respectively, within a clustercentric radius R 200 . The masses derived and/or luminosities show that fraction mass depletion timescale for are larger than expected scaling relations on stellar offset main sequence...
The incidence of Active Galactic Nuclei (AGN) with local environment is a potentially valuable probe the mechanisms that trigger and provide fuel for accretion onto supermassive black holes. While correlation between AGN fraction has been well-studied in universe, fractions have measured relatively few dense environments at high redshift. In this paper we present measurement X-ray USS 1558-003 protocluster associated z=2.53 radio galaxy 4C-00.62. Our based on 100ks Chandra observation,...
We report a detailed CO(1−0) survey of galaxy protocluster field at z = 2.16, based on 475 h observations with the Australia Telescope Compact Array. constructed large mosaic 13 individual pointings, covering an area 21 arcmin 2 and ±6500 km s −1 range in velocity. obtained robust sample 46 detections spanning 2.09 − 2.22, constituting largest molecular gas measurements protoclusters to date. The CO emitters show overdensity 2.12 2.21, suggesting super-protocluster or connected large-scale...
We report the discovery of a strong over-density galaxies in field radio galaxy at z=1.52 (4C65.22) based on our broad-band and narrow-band (H-alpha) photometry with Subaru Telescope. find that H-alpha emitters are located outskirts density peak (cluster core) dominated by passive red-sequence galaxies. This resembles situation lower-redshift clusters, suggesting newly discovered structure is well-evolved rich cluster z=1.5. Our data suggest color-density stellar mass-density relations...
We have carried out a panoramic Ly$\alpha$ narrowband imaging with Suprime-Cam on Subaru towards the known protocluster USS1558--003 at $z=2.53$. Our previous near-infrared has identified multiple dense groups of H$\alpha$ emitters (HAEs) within protocluster. now large-scale structures across $\sim$50 comoving Mpc scale traced by (LAEs) in which HAEs is embedded. On smaller scale, however, there are remarkably few LAEs regions HAE overdensities. Moreover, stacking analyses images show that...
ABSTRACT We use K-band multi-object near-infrared spectroscopy with Keck/MOSFIRE to search for environmental imprints on the gas properties of 27 narrow-band selected H α emitters (HAEs) across three major clumps assembling USS1558−003 protocluster at z = 2.53. target and [N ii]λ6584 emission lines obtain star formation rates (SFR) gas-phase oxygen abundances our sources, confirming membership 23 objects. HAEs belonging this display enhanced SFRs respect main sequence same cosmic epoch. This...
ABSTRACT Modern cosmological hydrodynamical galaxy simulations provide tens of thousands reasonably realistic synthetic galaxies across cosmic time. However, quantitatively assessing the level realism simulated universes in comparison to real one is difficult. In this paper Extracting Reality from Galaxy Observables with Machine Learning series, we utilize contrastive learning directly compare a large sample and observed based on their stellar-light images. This eliminates need specify...
ABSTRACT Low-mass galaxies at high redshifts are the building blocks of more massive later times and thus key populations for understanding galaxy formation evolution. We have made deep narrow-band observations two protoclusters general field in COSMOS z ∼ 2. In a clumpy young protocluster, USS1558−003, = 2.53, we find many star-forming well above main sequence low-mass end ($M_{\star }/\mathrm{{\rm M}_{\odot }}\lt 10^{8.9}$). This suggests that some environmental effects may be work...
Using star-forming galaxies sample in the nearby Universe (0.02<z<0.10) selected from SDSS (DR7) and GALEX all-sky survey (GR5), we present a new empirical calibration for predicting dust extinction of H-alpha-to-FUV flux ratio. We find that H-alpha (A(Ha)) derived with H-alpha/H-beta ratio (Balmer decrement) increases increasing H-alpha/UV as expected, but there remains considerable scatter around relation, which is largely dependent on stellar mass and/or equivalent width (EW(Ha)). At...