104 citations · 426 across the 35 of their papers we have counts for
36 papers
Gas-Phase Metallicity and Nitrogen Abundances in Low-Mass Galaxies Down to at -- from JWST Lensing Cluster Surveys
Hiroya Umeda, Masami Ouchi, Kimihiko Nakajima +7
We analyze 405 deep JWST/NIRSpec spectra of star-forming galaxies at -- from DREAMS and other lensing-cluster surveys to study chemical enrichment in intrinsically fai…
DREAMS. JWST Spectroscopy of a Galaxy with an ALMA Dust Continuum Detection: Early Dust, Very High , and a Multi-wavelength [OIII] Ratio Discrepancy
Kana Takechi, Masami Ouchi, Kimihiko Nakajima +10
We present a deep DREAMS JWST/NIRSpec MSA medium-grating spectrum of MACS0416-Y1, a galaxy at with the highest-redshift ALMA dust continuum detection to date, in order to…
Nuclear Physics of X-ray Bursts
Yi Xu, Hendrik Schatz, Rita Lau +2
Thermonuclear X-ray bursts from the surface of accreting neutron stars are the most common astrophysical explosions in our galaxy. They provide a unique window into the physics of…
A UV-Luminous Galaxy at z=11 with Surprisingly Weak Star Formation Activity
Yuichi Harikane, Pablo G. Perez-Gonzalez, Javier Alvarez-Marquez +8
One of the major discoveries by the James Webb Space Telescope (JWST) is the identification of a large population of luminous galaxies at , challenging theoretical models for…
A spectroscopically confirmed, strongly lensed, metal-poor Type II supernova at z = 5.13
David A. Coulter, Conor Larison, Justin D. R. Pierel +88
Observing supernovae (SNe) in the early Universe (z > 3) provides a window into how both galaxies and individual stars have evolved over cosmic time, yet a detailed study of high-r…
An Ultra-Faint, Chemically Primitive Galaxy Forming in the Reionization Era
Kimihiko Nakajima, Masami Ouchi, Yuichi Harikane +9
The formation of the first stars and galaxies marked the onset of chemical enrichment, yet direct observations of such primordial systems remain elusive. Here we present James Webb…
SAPPHIRES: Extremely Metal-Poor Galaxy Candidates with at from Deep JWST/NIRCam Grism Observations
Tiger Yu-Yang Hsiao, Fengwu Sun, Xiaojing Lin +19
Population III stars, the hypothetical first generation metal-free stars, have yet to be discovered. Even after three years of successful JWST operations, studies have shown that m…
Comprehensive JWST+ALMA Study on the Extended Ly Emitters, Himiko and CR7 at : Blue Major Merger Systems in Stark Contrast to Submillimeter Galaxies
Tomokazu Kiyota, Masami Ouchi, Yi Xu +14
We present various properties of two bright extended Ly objects, Himiko and CR7, at thoroughly investigated with JWST/NIRCam photometry, NIRSpec-IFU spectroscopy, and AL…
SAPPHIRES: A Galaxy Over-Density in the Heart of Cosmic Reionization at
Yoshinobu Fudamoto, Jakob M. Helton, Xiaojing Lin +17
We report the discovery of a galaxy proto-cluster candidate (dubbed MACS0416-OD-z8p5) at a spectroscopic redshift of , dating back to Myr after the Big Bang. Th…
Slitless Areal Pure-Parallel HIgh-Redshift Emission Survey (SAPPHIRES): Early Data Release of Deep JWST/NIRCam Images and Spectra in MACS J0416 Parallel Field
Fengwu Sun, Yoshinobu Fudamoto, Xiaojing Lin +25
We present the early data release (EDR) of SAPPHIRES, a JWST Cycle-3 Treasury imaging and spectroscopic survey using the powerful NIRCam wide-field slitless spectroscopic (WFSS) mo…
Morphological Demographics of Galaxies at : Log-Normal Size Distribution and Exponential Profiles Consistent with the Disk Formation Scenario
Yoshiaki Ono, Masami Ouchi, Yuichi Harikane +5
We homogeneously investigate the morphological properties of galaxies at with deep JWST NIRCam images employing our established techniques of GALFIT modeling and…
EMPRESS. X. Spatially resolved mass-metallicity relation in extremely metal-poor galaxies: evidence of episodic star-formation fueled by a metal-poor gas infall
Kimihiko Nakajima, Masami Ouchi, Yuki Isobe +47
Using the Subaru/FOCAS IFU capability, we examine the spatially resolved relationships between gas-phase metallicity, stellar mass, and star-formation rate surface densities (Sigma…
A Galaxy with an Extremely Blue UV Slope at Identified by JWST Spectroscopy: Evidence for a Weak Nebular Continuum and Efficient Ionizing Photon Escape?
Hiroto Yanagisawa, Masami Ouchi, Kimihiko Nakajima +8
We investigate UV continuum slopes of 863 galaxies at using archival JWST/NIRSpec PRISM spectra obtained from major JWST GTO, ERS, and GO programs, including JADES, CE…
The Physical Origin of Extreme Emission Line Galaxies at High redshifts: Strong {\sc [Oiii]} Emission Lines Produced by Obscured AGNs
Chenghao Zhu, Yuichi Harikane, Masami Ouchi +21
We present deep Subaru/FOCAS spectra for two extreme emission line galaxies (EELGs) at with strong {\sc[Oiii]}5007 emission lines, exhibiting equivalent widths (EWs) o…
JWST, ALMA, and Keck Spectroscopic Constraints on the UV Luminosity Functions at z~7-14: Clumpiness and Compactness of the Brightest Galaxies in the Early Universe
Yuichi Harikane, Akio K. Inoue, Richard S. Ellis +33
We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at . Our sample is composed of 60 galaxies at $z_\mathrm{spec}…
Strong He I Emission Lines in High N/O Galaxies at Identified in JWST Spectra: High He/H Abundance Ratios or High Electron Densities?
Hiroto Yanagisawa, Masami Ouchi, Kuria Watanabe +14
We present HeI/H-flux and He/H-abundance ratios in three JWST galaxies with significant constraints on N/O-abundance ratios, GS-NDG-9422, RXCJ2248-ID, and GLASS150008 at $z\sim…
Dynamics of a Galaxy at z > 10 Explored by JWST Integral Field Spectroscopy: Hints of Rotating Disk Suggesting Weak Feedback
Yi Xu, Masami Ouchi, Hidenobu Yajima +9
We investigate the dynamics of GN-z11, a luminous galaxy at , carefully analyzing the public deep integral field spectroscopy (IFS) data taken with JWST NIRSpec IFU. While…
Balmer Decrement Anomalies in Galaxies at z ~ 6 Found by JWST Observations: Density-Bounded Nebulae or Excited H I Clouds?
Hiroto Yanagisawa, Masami Ouchi, Kimihiko Nakajima +11
We investigate the physical origins of the Balmer decrement anomalies in GS-NDG-9422 (Cameron et al. 2023) and RXCJ2248-ID (Topping et al. 2024) galaxies at whose $\mathr…
Ly Emission at : Clear Ly Equivalent Width Evolution Indicating the Late Cosmic Reionization History
Minami Nakane, Masami Ouchi, Kimihiko Nakajima +6
We present the evolution of Ly emission derived from 53 galaxies at that are identified by multiple JWST/NIRSpec spectroscopy programs of ERS, GO, DDT, and GTO. The…
Stellar- and AGN-Driven Outflows in JWST Galaxies at z=3-9: More Frequent, Wider Opening Angles, and Mostly Bounded
Yi Xu, Masami Ouchi, Kimihiko Nakajima +5
We study outflows in 130 galaxies with -22<MUV<-16 at z=3-9 identified in JWST NIRSpec and NIRCam WFSS data taken by the ERO, CEERS, FRESCO, GLASS, and JADES programs. We identify…
Census for the Rest-frame Optical and UV Morphologies of Galaxies at : First Phase of Inside-Out Galaxy Formation
Yoshiaki Ono, Yuichi Harikane, Masami Ouchi +7
We present the rest-frame optical and UV surface brightness (SB) profiles for galaxies with mag at - ( of which are spectroscopically confir…
JWST Identification of Extremely Low C/N Galaxies with [N/O] at Evidencing the Early CNO-Cycle Enrichment and a Connection with Globular Cluster Formation
Yuki Isobe, Masami Ouchi, Nozomu Tominaga +9
We present chemical abundance ratios of 70 star-forming galaxies at -10 observed by the JWST/NIRSpec ERO, GLASS, and CEERS programs. Among the 70 galaxies, we have pinpoint…
Statistics for Galaxy Outflows at with Imaging and Spectroscopic Signatures Identified with JWST/NIRCam and NIRSpec Data
Yechi Zhang, Masami Ouchi, Kimihiko Nakajima +5
We present statistics of galaxy outflows indicated by spatially-extended gas emission and broad lines. With a total of 61 spectroscopically confirmed galaxies at $z\sim…
JWST Measurements of Neutral Hydrogen Fractions and Ionized Bubble Sizes at Obtained with Ly Damping Wing Absorptions in 27 Bright Continuum Galaxies
Hiroya Umeda, Masami Ouchi, Kimihiko Nakajima +5
We present volume-averaged neutral hydrogen fractions $x_{\rm \HI}$ and ionized bubble radii measured with Ly damping wing absorption of galaxies at the epoch of rei…