JWST, ALMA, and Keck Spectroscopic Constraints on the UV Luminosity Functions at <i>z</i> ∼ 7–14: Clumpiness and Compactness of the Brightest Galaxies in the Early Universe

Abstract We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z ∼ 7–14. Our sample is composed of 60 galaxies at z spec ∼ 7–14, including recently confirmed galaxies at z spec = 12.34–14.18 with JWST, as well as new confirmations at z spec = 6.583–7.643 with −24 &lt; M UV &lt; −21 mag using ALMA and Keck. Our JWST/NIRSpec observations have also revealed that very bright galaxy candidates at z ∼ 10–13 identified from ground-based telescope images before JWST are passive galaxies at z ∼ 3–4, emphasizing the necessity of strict screening and spectroscopy in the selection of the brightest galaxies at z &gt; 10. The UV luminosity functions derived from these spectroscopic results are consistent with a double power-law function, showing tensions with theoretical models at the bright end. To understand the origin of the overabundance of bright galaxies, we investigate their morphologies using JWST/NIRCam high-resolution images obtained in various surveys, including PRIMER and COSMOS-Web. We find that ∼70% of the bright galaxies at z ∼ 7 exhibit clumpy morphologies with multiple subcomponents, suggesting merger-induced starburst activity, which is consistent with SED fitting results showing bursty star formation histories. At z ≳ 10, bright galaxies are classified into two types of galaxies: extended ones with weak high-ionization emission lines, and compact ones with strong high-ionization lines including N iv] λ 1486, indicating that at least two different processes (e.g., merger-induced starburst and compact star formation/AGN) are shaping the physical properties of the brightest galaxies at z ≳ 10 and are responsible for their overabundance.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-02-07
DOI
https://doi.org/10.3847/1538-4357/ad9b2c
Citations
64
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
73.91
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article

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

Seiji Fujimoto, Eiichi Egami, Adam C. Carnall, R. Sato et al.
64 citations
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
73.91
article

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

Seiji Fujimoto, Eiichi Egami, Adam C. Carnall, R. Sato, Yurina Nakazato, Yoichi Tamura, Fengwu Sun, Nicolas Laporte, Nobunari Kashikawa, Chien‐Hsiu Lee, Norman A. Grogin, Yuma Sugahara, J. S. Dunlop, Masami Ouchi, Yuichi Harikane, Yoshiaki Ono, Anton M. Koekemoer, Ken Mawatari, S. Yamanaka, Hiroya Umeda, Yoshiki Matsuoka, Pablo G. Pérez‐González, D J McLeod, Hiroshi Matsuo, Marcin Sawicki, Fergus Cullen, Giovanni Ferrami, Minami Nakane, Richard S. Ellis, Akio Inoue, D. Magee, Hiroto Yanagisawa, Naoki Yoshida, Yuki Isobe, Yi Xu, Kimihiko Nakajima
article en
64 citations

Abstract

Abstract We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z ∼ 7–14. Our sample is composed of 60 galaxies at z spec ∼ 7–14, including recently confirmed galaxies at z spec = 12.34–14.18 with JWST, as well as new confirmations at z spec = 6.583–7.643 with −24 &lt; M UV &lt; −21 mag using ALMA and Keck. Our JWST/NIRSpec observations have also revealed that very bright galaxy candidates at z ∼ 10–13 identified from ground-based telescope images before JWST are passive galaxies at z ∼ 3–4, emphasizing the necessity of strict screening and spectroscopy in the selection of the brightest galaxies at z &gt; 10. The UV luminosity functions derived from these spectroscopic results are consistent with a double power-law function, showing tensions with theoretical models at the bright end. To understand the origin of the overabundance of bright galaxies, we investigate their morphologies using JWST/NIRCam high-resolution images obtained in various surveys, including PRIMER and COSMOS-Web. We find that ∼70% of the bright galaxies at z ∼ 7 exhibit clumpy morphologies with multiple subcomponents, suggesting merger-induced starburst activity, which is consistent with SED fitting results showing bursty star formation histories. At z ≳ 10, bright galaxies are classified into two types of galaxies: extended ones with weak high-ionization emission lines, and compact ones with strong high-ionization lines including N iv] λ 1486, indicating that at least two different processes (e.g., merger-induced starburst and compact star formation/AGN) are shaping the physical properties of the brightest galaxies at z ≳ 10 and are responsible for their overabundance.

The Astrophysical JournalVol. 980(1)
Openalex Percentile: Top 0%
Galaxies: Formation, Evolution, Phenomena
73.91
DOIOpen Access PDFOpenAlex
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