533 citations · 1.1k across the 32 of their papers we have counts for
33 papers
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…
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…
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…
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…
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…
EMPRESS. XIV. Strong High Ionization Lines of Young Galaxies at : Ionizing Spectra Consistent with the Intermediate Mass Black Holes with
Shun Hatano, Masami Ouchi, Hiroya Umeda +16
We present ionizing spectra estimated at 13.6--100 eV for ten dwarf galaxies with strong high ionization lines of He {\sc {ii}}4686 and [Ne {\sc{v}}]3426 ([Ne {\sc{iv}}]24…
Pure Spectroscopic Constraints on UV Luminosity Functions and Cosmic Star Formation History From 25 Galaxies at Confirmed with JWST/NIRSpec
Yuichi Harikane, Kimihiko Nakajima, Masami Ouchi +5
We present pure spectroscopic constraints on the UV luminosity functions and cosmic star formation rate (SFR) densities from 25 galaxies at . By reducin…
Near-infrared Variability Detected in the Young Star-Forming Dwarf Galaxy SBS 0335-052E
Shun Hatano, Mitsuru Kokubo, Masami Ouchi +17
SBS~0335-052E is a young star-forming dwarf galaxy with a total stellar mass of and an extremely low metallicity (), which…
The Stellar Mass - Black Hole Mass Relation at Down to Determined by HETDEX
Yechi Zhang, Masami Ouchi, Karl Gebhardt +14
We investigate the stellar mass - black hole mass () relation with type 1 AGN down to , corresponding t…
EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of Extremely-Metal Poor Galaxies
Yi Xu, Masami Ouchi, Yuki Isobe +49
We present demography of the dynamics and gas-mass fraction of 33 extremely metal-poor galaxies (EMPGs) with metallicities of and low stellar masses of $10^4-…
A JWST/NIRSpec First Census of Broad-Line AGNs at z=4-7: Detection of 10 Faint AGNs with M_BH~10^6-10^8 M_sun and Their Host Galaxy Properties
Yuichi Harikane, Yechi Zhang, Kimihiko Nakajima +6
We present a first statistical sample of faint type-1 AGNs at identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at confirmed with…
HETDEX Public Source Catalog 1: 220K Sources Including Over 50K Lyman Alpha Emitters from an Untargeted Wide-area Spectroscopic Survey
Erin Mentuch Cooper, Karl Gebhardt, Dustin Davis +43
We present the first publicly released catalog of sources obtained from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). HETDEX is an integral field spectroscopic survey…
The HETDEX Survey: Emission Line Exploration and Source Classification
Dustin Davis, Karl Gebhardt, Erin Mentuch Cooper +20
The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is an untargeted spectroscopic survey that aims to measure the expansion rate of the Universe at to 1% preci…
JWST Census for the Mass-Metallicity Star-Formation Relations at z=4-10 with the Self-Consistent Flux Calibration and the Proper Metallicity Calibrators
Kimihiko Nakajima, Masami Ouchi, Yuki Isobe +5
We present the evolution of the mass-metallicity (MZ) relations at z=4-10 derived with 135 galaxies identified in the JWST/NIRSpec data taken from the three major public spectrosco…
Redshift Evolution of the Electron Density in the ISM at Uncovered with JWST/NIRSpec Spectra and Line-Spread Function Determinations
Yuki Isobe, Masami Ouchi, Kimihiko Nakajima +5
We present electron densities in the inter-stellar medium (ISM) of star-forming galaxies at observed by the JWST/NIRSpec GLASS, ERO, and CEERS programs. We care…
Cosmological-Scale Lyman-alpha Forest Absorption Around Galaxies and AGN Probed with the HETDEX and SDSS Spectroscopic Data
Dongsheng Sun, Ken Mawatari, Masami Ouchi +12
We present cosmological-scale 3-dimensional (3D) neutral hydrogen ({\sc Hi}) tomographic maps at over a total of 837 deg in two blank fields that are developed with Ly$…