104 citations · 187 across the 18 of their papers we have counts for
19 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…
Chemical Abundance Ratios of Nitrogen Rich Galaxies Identified at : Observational Demographics and Models
Kuria Watanabe, Masami Ouchi, Kimihiko Nakajima +13
We present chemical abundance ratios of 8 nitrogen-rich ([N/O]) galaxies at identified by the first 4 years of the JWST observations, and compare these ratios wi…
Back to Normal Again: Possible Destinies of JWST overmassive SMBHs and "Little Red Dots" in the View of Shin-Uchuu Simulation
Haojie Hu, Hiroto Yanagisawa, Moka Nishigaki +3
The James Webb Space Telescope (JWST) has enabled the discovery of hundreds of supermassive black holes (SMBHs) at redshifts . A non-negligible fraction of these SMBH…
JWST Spectroscopic Census of ALMA Faint Submillimeter Galaxies in the Hubble Ultra Deep Field
Tomokazu Kiyota, Masami Ouchi, Daisuke Iono +6
We present a JWST/NIRSpec rest-frame optical spectroscopic census of ALMA 1-mm continuum sources in the Hubble Ultra Deep Field (UDF) identified by the deep ALMA UDF and ASPECS pro…
DREAMS.II. Galaxy Demographics from Direct Te-Based Metallicities at z~2-10: Tracing the Evolution of the Mass-Metallicity and Fundamental Relations
Moka Nishigaki, Kimihiko Nakajima, Masami Ouchi +6
We present the statistics of line ratios and direct Te-based metallicities from JWST medium-resolution spectra of 292 galaxies at z=2-10, combining DREAMS observations with those o…
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…
ChemicalUniverseMachine I: Uncovering the Cosmic Evolution of Metals in the Galaxy-ISM-CGM Ecosystem
Moka Nishigaki, Peter Behroozi, Masami Ouchi +5
We present an empirical chemical evolution model that explains the distribution of metals in the interstellar medium (ISM) and the circumgalactic medium (CGM) of galaxies based on…
Fe Abundances of Early Galaxies at Derived with Deep JWST Spectra
Minami Nakane, Masami Ouchi, Kimihiko Nakajima +12
We derive Fe-abundance ratios of 7 galaxies at with whose JWST/NIRSpec spectra achieve very high signal-to-noise ratios, , a…
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…
Low [O/Fe] Ratio in a Luminous Galaxy at the Early Cosmic Epoch (): Signature of Short Delay Time or Bright Hypernovae/Pair-Instability Supernovae?
Minami Nakane, Masami Ouchi, Kimihiko Nakajima +12
We present an [O/Fe] ratio of a luminous galaxy GN-z11 at derived with the deep public JWST/NIRSpec data. We fit the medium-resolution grating (G140M, G235M, and G395M) d…
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…
EMPRESS. XIII. Chemical Enrichments of Young Galaxies Near and Far at z ~ 0 and 4-10: Fe/O, Ar/O, S/O, and N/O Measurements with Chemical Evolution Model Comparisons
Kuria Watanabe, Masami Ouchi, Kimihiko Nakajima +14
We present gas-phase elemental abundance ratios of 7 local extremely metal-poor galaxies (EMPGs) including our new Keck/LRIS spectroscopy determinations together with 33 JWST $z\si…
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…
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-…
EMPRESS. XI. SDSS and JWST Search for Local and z~4-5 Extremely Metal-Poor Galaxies (EMPGs): Clustering and Chemical Properties of Local EMPGs
Moka Nishigaki, Masami Ouchi, Kimihiko Nakajima +16
We search for local extremely metal-poor galaxies (EMPGs), selecting photometric candidates by broadband color excess and machine-learning techniques with the SDSS photometric data…
Classification of cosmic structures for galaxies with deep learning: connecting cosmological simulations with observations
Shigeki Inoue, Xiaotian Si, Takashi Okamoto +1
We explore the capability of deep learning to classify cosmic structures. In cosmological simulations, cosmic volumes are segmented into voids, sheets, filaments and knots, accordi…
EMPRESS. V. Metallicity Diagnostics of Galaxies over 12+log(O/H)=~6.9-8.9 Established by a Local Galaxy Census: Preparing for JWST Spectroscopy
Kimihiko Nakajima, Masami Ouchi, Yi Xu +13
We present optical-line gas metallicity diagnostics established by the combination of local SDSS galaxies and the largest compilation of extremely metal-poor galaxies (EMPGs) inclu…
EMPRESS. IX. Extremely Metal-Poor Galaxies are Very Gas-Rich Dispersion-Dominated Systems: Will JWST Witness Gaseous Turbulent High-z Primordial Galaxies?
Yuki Isobe, Masami Ouchi, Kimihiko Nakajima +49
We present kinematics of 6 local extremely metal-poor galaxies (EMPGs) with low metallicities () and low stellar masses (). Tak…
EMPRESS. IV. Extremely Metal-Poor Galaxies (EMPGs) Including Very Low-Mass Primordial Systems with M*=10^4--10^5 M_sun and 2--3% (O/H)_sun: High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-Instability Supernovae
Yuki Isobe, Masami Ouchi, Akihiro Suzuki +22
We present Keck/LRIS follow-up spectroscopy for 13 photometric candidates of extremely metal poor galaxies (EMPGs) selected by a machine-learning technique applied to the deep (~26…