Y. Harikane

Spatially Resolved Physical Properties of Young Star Clusters and Star-forming Clumps in the Brightest z>6 Galaxy, the Strongly Lensed Cosmic Spear at z=6.2

Abdurro'uf, Dan Coe, Tom Resseguier +49

We present spatially resolved analysis of stellar populations in the brightest $z > 6$ galaxy known to date (AB mag 23), the strongly lensed MACS0308 $-$ zD1 (dubbed the ``Cosmic Spear…

Little red dot variability over a century reveals black hole envelope via a giant Einstein cross

Zijian Zhang, Mingyu Li, Masamune Oguri +79

"Little red dots" (LRDs) represent a new population of astronomical objects uncovered by JWST whose nature remains debated. Although many LRDs are suspected as active galactic nucl…

VENUS: When Red meets Blue -- A multiply imaged Little Red Dot with an apparent blue companion behind the galaxy cluster Abell 383

Miriam Golubchik, Lukas J. Furtak, Joseph F. V. Allingham +50

We report the discovery of a doubly-imaged Little Red Dot (LRD) candidate behind the galaxy cluster Abell 383, which we dub A383-LRD1. Initially classified as a dropout galaxy in H…

astro-ph.GA2025★ 9 cited

A Black-Hole Envelope Interpretation for Cosmological Demographics of Little Red Dots

Hiroya Umeda, Kohei Inayoshi, Yuichi Harikane +1

Little red dots (LRDs) newly discovered with JWST are active galactic nuclei (AGN) that may represent black hole (BH) growth at the earliest cosmic epochs. These sources show puzzl…

Galaxy Protoclusters as Drivers of Cosmic Reionization: I. Bubble Overlap at Redshift z ~ 7 in LAGER-z7OD1

Crystal L. Martin, Weida Hu, Isak G. B. Wold +17

Since the launch of JWST, the sample size of reionization-era Lyman-alpha-emitters (LAEs) has been steadily growing; yet inferences about the neutral hydrogen fraction in the inter…

RIOJA. The dusty outflows and density-complex interstellar medium in the N-enhanced lensed galaxy RXCJ2248-ID at z=6.1

A. Crespo Gómez, Y. Tamura, L. Colina +19

We present an analysis on the kinematics and physical properties of the ionized gas in the lensed galaxy RXCJ2248-ID at z=6.1 based on high-resolution JWST NIRSpec/IFU data in comb…

VENUS: A Strongly Lensed Clumpy Galaxy at $z \sim 11 - 12$ behind the Galaxy Cluster MACS J0257.1-2325

Minami Nakane, Vasily Kokorev, Seiji Fujimoto +75

We present the discovery of a strongly lensed galaxy at $z \sim 11 - 12$ , dubbed the ``Misty Moons'', identified in the JWST Treasury Survey, Vast Exploration for Nascent, Unexplored S…

Discovery of a Little Red Dot candidate at $z ≳ 10$ in COSMOS-Web based on MIRI-NIRCam selection

Takumi S. Tanaka, Hollis B. Akins, Yuichi Harikane +64

JWST has revealed a new high-redshift population called little red dots (LRDs). Since LRDs may be in the early phase of black hole growth, identifying them in the early universe is…

Compact Ionized Gas Region Surrounded by Porous Neutral Gas in a Dusty Lyman Break Galaxy at Redshift $z = 8.312$

Masato Hagimoto, Yoichi Tamura, Akio K. Inoue +9

Porous interstellar medium (ISM) structure in galaxies at the epoch of reionization (EoR) gives us a hint to understand what types of galaxies contribute to reionization. Although…

EMPRESS. XV. A New Determination of the Primordial Helium Abundance Suggesting a Moderately Low $Y_{P}$ Value

Hiroto Yanagisawa, Masami Ouchi, Akinori Matsumoto +18

We present a new constraint on the primordial helium abundance, $Y_{P}$ , based on Subaru observations. A major source of uncertainty in previous $Y_{P}$ determination…

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…

astro-ph.GA2025★ 4 cited

SAPPHIRES: Extremely Metal-Poor Galaxy Candidates with $12 + log (O/H) < 7.0$ at $z \sim 5 - 7$ 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…

JWST & ALMA Joint Analysis with [OII] $λλ$ 3726,3729, [OIII] $λ$ 4363, [OIII]88 $μ$ m, and [OIII]52 $μ$ m: Multi-Zone Evolution of Electron Densities at $z \sim 0 - 14$ and Its Impact on Metallicity Measurements

Yuichi Harikane, Ryan L. Sanders, Richard Ellis +8

We present a JWST and ALMA detailed study of the ISM properties of high-redshift galaxies. Our JWST/NIRSpec IFU spectroscopy targeting three galaxies at $z = 6 - 7$ detects key rest-fr…

Probing the Cosmic Reionization History with JWST: Gunn-Peterson and Ly $α$ Damping Wing Absorption at $4.5 < z < 13$

Hiroya Umeda, Masami Ouchi, Yuta Kageura +4

We present a statistical analysis of Ly $α$ absorption using 581 galaxies at $z = 4.5$ --13 observed with multiple JWST/NIRSpec spectroscopy programs, including JADES, UNCOVER, CEERS,…

Comprehensive JWST+ALMA Study on the Extended Ly $α$ Emitters, Himiko and CR7 at $z \sim 7$ : 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 $α$ objects, Himiko and CR7, at $z = 6.6$ thoroughly investigated with JWST/NIRCam photometry, NIRSpec-IFU spectroscopy, and AL…

astro-ph.GA2025★ 4 cited

SAPPHIRES: A Galaxy Over-Density in the Heart of Cosmic Reionization at $z = 8.47$

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 $z \sim 8.47$ , dating back to $\sim 550$ Myr after the Big Bang. Th…

astro-ph.GA2025★ 3 cited

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…

UNIONS: The Ultraviolet Near-Infrared Optical Northern Survey

Stephen Gwyn, Alan W. McConnachie, Jean-Charles Cuillandre +86

The Ultraviolet Near-Infrared Optical Northern Survey (UNIONS) is a "collaboration of collaborations" that is using the Canada-France-Hawai'i Telescope, the Pan-STARRS telescopes,…

Fe Abundances of Early Galaxies at $z = 9 - 12$ Derived with Deep JWST Spectra

Minami Nakane, Masami Ouchi, Kimihiko Nakajima +12

We derive Fe-abundance ratios of 7 galaxies at $z = 9 - 12$ with $- 22 < M_{UV} < - 19$ whose JWST/NIRSpec spectra achieve very high signal-to-noise ratios, $SNR = 60 - 320$ , a…

Morphological Demographics of Galaxies at $z \sim 10 - 16$ : 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 $169$ galaxies at $z \sim 10 - 16$ with deep JWST NIRCam images employing our established techniques of GALFIT modeling and…