M. Yoshida
A5017180905- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Planetary Science and Exploration
- Particle Detector Development and Performance
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- CCD and CMOS Imaging Sensors
- Spectroscopy and Laser Applications
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Isotope Analysis in Ecology
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
National Astronomical Observatory of Japan
2011-2024
National Institutes of Natural Sciences
2008-2024
Nitto RIKEN (Japan)
2024
Japan Aerospace Exploration Agency
2024
Institute of Space and Astronautical Science
2024
Subaru (Japan)
2017-2023
Hiroshima University
2011-2020
Canada–France–Hawaii Telescope
2020
Clark Atlanta University
2018
University of Alaska Anchorage
2018
We present Lya luminosity function (LF), clustering measurements, and line profiles based on the largest sample, to date, of 207 emitters (LAEs) at z=6.6 1-deg^2 sky Subaru/XMM-Newton Deep Survey (SXDS) field. Our LF including cosmic variance estimates yields best-fit Schechter parameters phi*=8.5 +3.0/-2.2 x10^(-4) Mpc^(-3) L*(Lya)=4.4 +/-0.6 x10^42 erg s^(-1) with a fixed alpha=-1.5, indicates decrease from z=5.7 >~90% confidence level. However, this is not large, only =~30% in luminosity,...
We present luminosity functions (LFs) and various properties of Lya emitters (LAEs) at z=3.1, 3.7, 5.7, in a 1 deg^2 sky the Subaru/XMM-Newton Deep Survey (SXDS) Field. obtain photometric sample 858 LAE candidates based on deep Subaru/Suprime-Cam imaging data, spectroscopic 84 confirmed LAEs from Subaru/FOCAS VLT/VIMOS spectroscopy survey volume ~10^6 Mpc^3 with limiting ~3x10^42 erg/s. derive LFs UV-continuum (~1500 Å) for each redshift, taking into account statistical error field-to-field...
The first detected gravitational wave from a neutron star merger was GW170817. In this study, we present J-GEM follow-up observations of SSS17a, an electromagnetic counterpart SSS17a shows 2.5-mag decline in the $z$-band 1.7 days to 7.7 after merger. Such rapid is not comparable with supernovae light curves at any epoch. color also evolves rapidly and becomes redder for later epochs; $z-H$ changed by approximately 2.5 mag period 0.7 days. evolution both optical brightness are consistent...
Abstract We present the design and performance of High Dispersion Spectrograph (HDS) Subaru Telescope. HDS is an echelle spectrograph located at Nasmyth focus telescope. The collimated beam size 272 mm, 300 mm by 840 in total ($31.6 \,\mathrm{gr} \,\mathrm{mm}^{-1}, R=2.8$). has two cross-dispersing gratings with $400 \,\mathrm{mm}^{-1}$ $250 \,\mathrm{mm}^{-1}$, which are optimized for blue red wavelength regions, respectively. camera catadioptric type system, consisting three corrector...
Abstract The Faint Object Camera and Spectrograph (FOCAS) is a Cassegrain optical instrument for the Subaru Telescope. Its capabilities include $6^\prime \phi$ FOV direct imaging, low-resolution spectroscopy ($R=250 \hbox{--} 2000$ with ${0\rlap {.}{}^{\mathrm {\prime \prime }}4}$ slitwidth), multi-slit polarimetry. We describe overall design of FOCAS, its observing functions, performance verification procedures that have been carried out.
We present multi-wave band optical imaging data obtained from observations of the Subaru/XMM-Newton Deep Survey (SXDS). The survey field, centered at R .A . = 02h18m00s, decl − 05°00'00'', has been focus a wide range multiwavelength observing programs spanning X-ray to radio wavelengths. A large part are carried out with Suprime-Cam on Subaru Telescope Mauna Kea in course "Observatory Projects." This paper describes our observations, reduction and analysis procedures employed,...
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 ($z^\prime-\mathit{NB921} \gt 1.0...
We report the discovery of primeval large-scale structures (LSSs) including two protoclusters in a forming phase at z = 5.7. carried out extensive deep narrowband imaging 1 deg2 sky Subaru/XMM-Newton Deep Field and obtained cosmic map 515 Lyα emitters (LAEs) volume with transverse dimension 180 Mpc × depth ~40 comoving units. This shows filamentary LSSs, clusters surrounding 10-40 scale voids, similar to present-day LSSs. Our spectroscopic follow-up observations identify overdense regions...
We have performed a deep optical imaging survey using narrowband filter ($NB921$) centered at $\lambda =$ 9196 \AA ~ together with $i^\prime$ and $z^\prime$ broadband filters covering an 814 arcmin$^2$ area of the Subaru Deep Field. obtained sample 73 strong $NB921$-excess objects based on following two color criteria; $z^\prime - NB921 > 1$ $i^\prime z^\prime 1.3$. then spectroscopy nine in our sample, identified least Ly$\alpha$ emitters at$z=6.541 \pm 0.002$ $z=6.578 0.002$, each which...
We report the results of a multi-band observing campaign on famous blazar 3C 279 conducted during phase increased activity from 2013 December to 2014 April, including first observations it with NuSTAR. The $\gamma$-ray emission source measured by Fermi-LAT showed multiple distinct flares reaching highest flux level in this object since beginning Fermi mission, $F(E > 100\,{\rm MeV})$ $10^{-5}$ photons cm$^{-2}$ s$^{-1}$, and doubling time scale as short 2 hours. spectrum one was very hard,...
We report the detection of an extrasolar planet orbiting Tau, one giant stars in Hyades open cluster. This is first ever discovered Precise Doppler measurements this star from Okayama Astrophysical Observatory have revealed Keplerian velocity variations with orbital period 594.9 ± 5.3 days, a semiamplitude 95.9 1.8 m s-1, and eccentricity 0.151 0.023. The minimum mass companion 7.6 0.2 MJ, semimajor axis 1.93 0.03 AU adopting stellar 2.7 0.1 M☉. age 625 Myr for cluster sets most secure upper...
Abstract Recent detection of gravitational waves from a neutron star (NS) merger event GW170817 and identification an electromagnetic counterpart provide unique opportunity to study the physical processes in NS mergers. To derive properties ejected material merger, we perform radiative transfer simulations kilonova, optical near-infrared emissions powered by radioactive decays r-process nuclei synthesized merger. We find that observed emission lasting for >10 d is explained 0.03 M⊙...
We use the deep wide-field optical imaging data of Subaru/XMM-Newton Deep Survey (SXDS) to discuss luminosity (mass) dependent galaxy colours down z'=25.0 (5 x 10^9 h_{70}^{-2} Msun) for z~1 galaxies in colour-selected high density regions. find an apparent absence on red colour-magnitude sequence below z'~24.2, corresponding ~M*+2 (~10^{10} with respect passively evolving at z~1. Galaxies brighter than M*-0.5 (8 10^{10} Msun), however, are predominantly systems, few blue star forming these...
We report the detection of a planetary-mass companion to G9 III giant star HD 104985 from precise Doppler velocity measurements made using High Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory. The radial variability this is best explained by an orbital motion with period 198.2 ± 0.3 days, semiamplitude 161 2 m s-1, and eccentricity 0.03 0.02. Assuming stellar mass 1.6 M☉, we obtained minimum semimajor axis 6.3MJ 0.78 AU, respectively, for companion. A probable...
An overview of the current status 8.2 m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by National Astronomical Observatory Japan is presented. The basic design concept verified performance telescope system are described. Also given instrument package offered to astronomical community, operation, some future plans. reported in a number SPIE papers as summer 2002 incorporated with updates included 2004 February. However, readers encouraged check most updated through home...
Abstract We report on the detection of 3 new extrasolar planets from a precise Doppler survey G and K giants at Okayama Astrophysical Observatory. The host stars, 18 Del (G6 III), $\xi $Aql (K0 III) HD81688 III-IV), are located in clump region HR diagram with estimated masses 2.1-2.3$M_{\odot}$. 18Del b has minimum mass $10.3 M_{\rm J}$ resides nearly circular orbit period 993d, which is longest one around evolved stars. $ Aql have 2.8 2.7$M_{\rm J}$, reside orbits periods 137 184d,...
We report the discovery of a giant Lyα emitter (LAE) with Spitzer/Infrared Array Camera (IRAC) counterpart near reionization epoch at z = 6.595. The LAE is found from extensive 1 deg2 Subaru narrowband survey for 6.6 LAEs in Subaru/XMM-Newton Deep Survey (SXDS) field, and subsequently identified by deep spectroscopy Keck/DEIMOS Magellan/IMACS. Among our 207 candidates, this not only brightest object L(Lyα) 3.9 ± 0.2 × 1043 erg s−1 volume 106 Mpc3, but also spatially extended nebula largest...
We present images of extended Hα clouds associated with 14 member galaxies in the Coma cluster obtained from deep narrowband imaging observations Suprime-Cam at Subaru Telescope. The parent are distributed farther than 0.2 Mpc peak X-ray emission cluster. Most bluer g − r ≈ 0.5 and they account for 57% blue (g < 0.5) bright (r 17.8 mag) central region They reside near red- blueshifted edges radial velocity distribution galaxies. Our findings suggest that most were recently captured by...
We report on the correlation between flux, color and polarization variations time scales of days--months in blazars, discuss their universal aspects. performed monitoring 42 blazars optical near-infrared bands from 2008 to 2010 using TRISPEC attached "Kanata" 1.5-m telescope. found that 28 exhibited "bluer-when-brighter" trends whole or a part time-series data sets. This corresponds 88% objects were observed for >10 days. Thus, our observation unambiguously confirmed trend is common emission...
We found an unusual complex of narrow blue filaments, bright knots, and Hα-emitting filaments clouds, which morphologically resembled a "fireballs," extending up to 80 kpc south from E+A galaxy RB 199 in the Coma Cluster. The has highly disturbed morphology indicative galaxy-galaxy merger remnant. extend straight shapes toward galaxy, several knots are located at southern ends filaments. RC band absolute magnitudes, half-light radii, estimated masses ~–12 –13 mag, ~200-300 pc, ~106-107 M☉,...
Abstract We report on the detections of substellar companions orbiting around seven evolved intermediate-mass stars from precise Doppler measurements at Okayama Astrophysical Observatory. $o$ UMa (G4 II-III) is a giant with mass 3.1 $M_{\odot}$ , and hosts planet minimum $m_2$ sin $i$$=$ 4.1 $M_{\rm J}$ in an orbit period $P$$=$ 1630 d eccentricity $e$$=$ 0.13. This first candidate ($\lt $ 13 ) ever discovered star more massive than 3 . CrB (K0 III) 2.1 giant, has 1.5 187.8 0.19. one...
Context. Over the past few years, on several occasions, large, continuous rotations of electric vector position angle (EVPA) linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy γ-ray flares and they attracted considerable attention, since could allow us to probe magnetic field structure in emitting region jet. The flat-spectrum radio quasar 3C 279 is one most prominent examples showing this behaviour.
ABSTRACT An overview of the Seimei telescope, a 3.8 m optical infrared telescope located on Mt. Chikurinji in Okayama prefecture Japan, is presented. segmented-mirror whose primary mirror consists 18 petal-shaped segments. The tube supporting thin segmented mirrors structurally incorporated within large arc-rails providing elevation axis. has light-weight homologous structure designed with genetic algorithm. total weight tube, including 1.4-ton optics, only 8 tons. By virtue its light...
Deep near-infrared images of a blank 2'x2' section sky near the Galactic north pole taken by Subaru Telescope are presented. The total integration times J and K' bands 12.1 hours 9.7 hours, resulting in 5-sigma limiting magnitudes 25.1 23.5 mag, respectively. numbers sources within these found with an automated detection procedure 385 band 350 K'. Based on photometric measurements sources, we present number count vs. magnitude relations, color diagrams, size relationships, etc. slope galaxy...
We found a very large, ~35 kpc, emission-line region around the Seyfert type 2 galaxy NGC 4388, using deep narrowband imaging with prime focus camera (Suprime-Cam) of Subaru Telescope. This consists many faint gas clouds, or filaments, and extends northeastward from galaxy. The typical Hα luminosity L(Hα) clouds is ~1037 ergs s-1, total within 10 kpc nucleus ~2 × 1038 which corresponds to an ionized mass ~105 M☉. map intensity ratio I([O III])/I(Hα) indicates that inner (r < 12 kpc) extended...