Tohru Nagao
A5034701878- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- CCD and CMOS Imaging Sensors
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Pulsars and Gravitational Waves Research
- Black Holes and Theoretical Physics
- Advanced Vision and Imaging
- Photocathodes and Microchannel Plates
- Particle Detector Development and Performance
- Remote Sensing in Agriculture
- Advanced Optical Sensing Technologies
- Astro and Planetary Science
- Mechanics and Biomechanics Studies
- Advanced Image Processing Techniques
Ehime University
2015-2024
Kagoshima University
2024
Osaka University
2020
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Kyoto University
2011-2014
Matsumoto University
2014
National Astronomical Observatory of Japan
2005-2011
Tohoku University
1999-2009
Japan Society for the Promotion of Science London
2008
Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of 8.2m Subaru telescope summit Maunakea in Hawaii. A team scientists from Japan, Taiwan and Princeton University using HSC to carry out 300-night multi-band survey high-latitude sky. The includes three layers: Wide layer will cover 1400 deg$^2$ five broad bands ($grizy$), with $5\,\sigma$ point-source depth $r \approx 26$. Deep covers total 26~deg$^2$ four fields, going roughly magnitude fainter, while UltraDeep goes...
We present imaging data and photometry for the COSMOS survey in 15 photometric bands between 0.3 2.4 μm. These include taken on Subaru 8.3 m telescope, KPNO CTIO 4 telescopes, CFHT 3.6 telescope. Special techniques are used to ensure that relative calibration is better than 1% across field of view. The absolute accuracy from standard-star measurements found be 6%. corrected using galaxy spectra, providing colors accurate 2% or better. Stellar counts agree well with expected values. Finally,...
We present initial results of an ESO-VLT large programme (AMAZE) aimed at determining the evolution mass-metallicity relation z>3 by means deep near-IR spectroscopy. Gas metallicities are measured, for sample nine star forming galaxies z~3.5, optical nebular lines redshifted into near-IR. Stellar masses accurately determined using Spitzer-IRAC data, which rest-frame stellar light in these distant galaxies. When compared with previous surveys, inferred z~3.5 shows much stronger than observed...
We report an extensive search for Lyman-alpha emitters (LAEs) at z=6.5 in the Subaru Deep Field. Subsequent spectroscopy with and Keck identified eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs z=6.5. Based on this spectroscopic sample 17, complemented by photometric 58 we have derived accurate luminosity function z=6.5, which reveals apparent deficit bright end ~0.75 mag fainter L*, compared that observed z=5.7. The difference LAE functions between z=5.7 6.5 is...
We present deep optical imaging observations of 2 square degree area, covered by the Cosmic Evolution Survey (COSMOS), made prime-focus camera (Supreme-Cam) on 8.2 m Subaru Telescope. Observations were done in six broadband [B (4459.7 Å), g' (4723.1 V (5483.8 r' (6213.0 i' (7640.8 z' (8855.0 Å)] and one narrowband (NB816) filters. A total 106 galaxies detected to ~ 26.5 mag. These data, combined with at u* K-band are used construct photometric catalogs for COSMOS, measure their redshifts,...
Abstract The Subaru Prime Focus Spectrograph (PFS) is a massively multiplexed fiber-fed optical and near-infrared three-arm spectrograph (Nfiber = 2400, 380 ≤ λ 1260 nm, 1 $_{.}^{\circ}$3 diameter field of view). Here, we summarize the science cases in terms provisional plans for 300-night survey. We describe to constrain nature dark energy via survey emission line galaxies spanning comoving volume 9.3 h−3 Gpc3 redshift range 0.8 < z 2.4. In each six bins, cosmological distances will...
The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey aimed at addressing some of the most outstanding questions in astronomy today, including nature dark matter and energy. has been awarded 300 nights observing time Telescope it started March 2014. This paper presents first public data release HSC-SSP. includes taken 1.7 years observations (61.5 nights) each Wide, Deep, UltraDeep layers covers about 108, 26, 4 square degrees down to depths i~26.4, ~26.5,...
In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of Cosmic Evolution Survey (COSMOS) field. The availability a large training set spectroscopic that extends faint magnitudes enabled comparable highest quality results presently available normal galaxies. We demonstrate morphologically extended, X-ray without optical variability are more accurately described by library galaxies (corrected emission lines) than active...
We carried out extended spectroscopic confirmations of Ly-alpha emitters (LAEs) at z=6.5 and 5.7 in the Subaru Deep Field. Now, total number spectroscopically confirmed LAEs is 45 54 5.7, respectively, least 81% (70%) our photometric candidates (5.7) have been identified as real LAEs. made careful measurements luminosity, both photometrically spectroscopically, to accurately determine rest-UV luminosity functions (LFs). The substantially improved evaluation LF shows an apparent deficit from...
AGN-driven outflows are invoked by galaxy evolutionary models to quench star formation and explain the origin of relations observed locally between super massive black holes their host galaxies. This work aims detect presence extended ionised in luminous quasars where we expect maximum activity both hole accretion. Currently, there only a few studies based on spatially resolved observations at high redshift, $z>2$. We analyse sample six (${\rm L>10^{47} \ erg/s}$) $z\sim2.4$, H-band using...
We present the first results from a near-IR spectroscopic survey of COSMOS field, using Fiber Multi-Object Spectrograph on Subaru telescope, designed to characterize star-forming galaxy population at $1.4<z<1.7$. The high-resolution mode is implemented detect H$\alpha$ in emission between $1.6{\rm -}1.8 \mathrm{\mu m}$ with $f_{\rm H\alpha}\gtrsim4\times10^{-17}$ erg cm$^{-2}$ s$^{-1}$. Here, we specifically focus 271 sBzK-selected galaxies that yield detection thus providing redshift and...
ABSTRACT We report the discovery of 15 quasars and bright galaxies at 5.7 < z 6.9. This is initial result from Subaru High- Exploration Low-Luminosity Quasars project, which exploits exquisite multiband imaging data produced by Hyper Suprime-Cam (HSC) Strategic Program survey. The candidate selection performed combining several photometric approaches including a Bayesian probabilistic algorithm to reject stars dwarfs. spectroscopic identification was carried out with Gran Telescopio...
We present our new ALMA observations targeting [OIII]88um, [CII]158um, [NII]122um, and dust continuum emission for three Lyman break galaxies at z=6.0293-6.2037 identified in the Subaru/Hyper Suprime-Cam survey. clearly detect [OIII] [CII] lines from all of 4.3-11.8sigma levels, identify multi-band two galaxies, allowing us to estimate infrared luminosities temperatures simultaneously. In conjunction with previous six z>6, we confirm that nine z=6-9 have high [OIII]/[CII] ratios...
Context. In November 2019, eROSITA on board of the Spektrum-Roentgen-Gamma (SRG) observatory started to map entire sky in X-rays. After four-year survey program, it will reach a flux limit that is about 25 times deeper than ROSAT. During SRG performance verification phase, observed contiguous 140 deg 2 area down final depth all-sky (eROSITA Final Equatorial-Depth Survey; eFEDS), with goal obtaining census X-ray emitting populations (stars, compact objects, galaxies, clusters and active...
We report the properties of 35 robust candidate Lyα blobs (LABs), which are larger than 16 arcsec2 in isophotal area and brighter 0.7 × 10-16 ergs s-1 cm-2, located around protocluster region at redshift z = 3.1 discovered by Steidel et al. SSA22 field, based on wide-field (31' 23') deep narrowband (NB497; 4977 Å, FWHM 77 Å) broadband (B, V, R) images taken with prime-focus camera Subaru Telescope. The two previously known giant LABs most luminous largest our survey volume 1.3 105 Mpc3....
Abstract We present the properties of Ly$\alpha$ emitters (LAEs) at $z=5.7$ in Subaru Deep Field. A photometric sample 89 LAE candidates was constructed from narrow-band data down to $\mathit{NB816} = 26.0$ (AB) a continuous $725 \,\mathrm{arcmin}^2$ area. Spectra 39 objects satisfying selection criteria for LAEs were obtained with and Keck II Telescopes, among which 28 confirmed LAEs, one nearby galaxy, eight unclassified. also spectra another 24 NB816-excess field, identifying six...
Abstract We present new results of a deep optical imaging survey using narrow band filter (NB921) centered at ${\lambda = 9196 \,\mbox{Å}}$ together with $B, V, R, i^\prime$, and $z^\prime$ broadband filters in the sky area Subaru Deep Field, which has been promoted as one legacy programs 8.2m Telescope. obtained photometric sample 58 $\mathrm{Ly}\,\alpha$ emitter candidates $z \approx 6.5 \hbox{--} 6.6$ among $\sim 180$ strong NB921-excess ($z^\prime-\mathit{NB921} \gt 1.0...
Generally the gas metallicity in distant galaxies can only be inferred by using a few prominent emission lines. Various theoretical models have been used to predict relationship between line fluxes and metallicity, suggesting that some ratios as diagnostics of galaxies. However, accurate empirical calibrations these flux from real galaxy spectra spanning wide range are still lacking. In this paper we provide such combination two sets spectroscopic data: one consisting low-metallicity with...
We report the detection of 2P_3/2 -> 2P_1/2 fine-structure line C+ at 157.74 micron in SDSSJ114816.64+525150.3 (hereafter J1148+5251), most distant known quasar, z=6.42, using IRAM 30-meter telescope. This is first [CII] high redshift, and also a Hyperluminous Infrared Galaxy (L_FIR > 10^13 Lsun). The detected significance level 8 sigma has luminosity 4.4 x 10^9 Lsun. L_[CII]/L_FIR ratio 2 10^-4, about an order magnitude smaller than observed local normal galaxies similar to...
We consider the effect of radiation pressure from ionizing photons on black hole (BH) mass estimates based application virial theorem to broad emission lines in AGN spectra. BH masses only product Δ V2R and neglecting can be severely underestimated, especially objects close Eddington limit. provide an empirical calibration correction for pressure, we show that it is consistent with a simple physical model which BLR clouds are optically thick have average column densities NH ∼ 1023 cm −2....
We obtained a deep wide-field (32' ? 24') narrowband (?c = 4977?,?? 77?) image of field including the protocluster at z 3.1 in SSA22a studied by Steidel et al. using Subaru Telescope. The we observed is about 10 times as large that detected 283 highly confident strong Ly? emitter candidates ~ down to 25.8 AB mag with equivalent width larger than 154 ?. These show nonuniform distribution beltlike region high surface density, which found extend over ~60 Mpc comoving scale. average number...
We present an investigation into how well the properties of accretion flow on to a supermassive black hole may be coupled those overlying hot corona. To do so, we specifically measure characteristic spectral index, Γ, power-law energy distribution, over range 2–10 keV, for X-ray selected, broad-lined radio-quiet active galactic nuclei (AGN) up z ∼ 2 in Cosmic Evolution Survey (COSMOS) and Extended Chandra Deep Field South (E-CDF-S). test previously reported dependence between Γ mass, full...
Abridged: Subaru Deep Field line-emitting galaxies in four narrow-band filters at low and intermediate redshifts are presented. Broad-band colors, follow-up optical spectroscopy, multiple NB used to distinguish Ha, [O II], III] emitters between of 0.07 1.47 construct their luminosity functions (LFs). These LFs derived down faint magnitudes, which allows for a more accurate determination the end slope. With large (N~200-900) sample each redshift interval, Schechter profile is fitted LF. Prior...
Using the first 50% of data collected for Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) observations on 1.8 deg$^2$ Cosmological Evolution (COSMOS) we estimate masses and star formation rates 3398 $M_*>10^{10}M_\odot $ star-forming galaxies at $4 < z 6$ a substantial population up to $M_* \gtrsim 10^{11.5} M_\odot$. We find that strong correlation between stellar mass rate seen lower redshift (the "main sequence" galaxies) extends $z\sim6$. The observed relation scatter is...