Metal-enriched Neutral Gas Reservoir around a Strongly Lensed Low-mass Galaxy at z = 4 Identified by JWST/NIRISS and VLT/MUSE
Journal article, 2023
Direct observations of low-mass, low-metallicity galaxies at z ≳ 4 provide an indispensable opportunity for detailed inspection of the ionization radiation, gas flow, and metal enrichment in sources similar to those that reionized the universe. Combining the James Webb Space Telescope (JWST), Very Large Telescope/MUSE, and Atacama Large Millimeter/submillimeter Array, we present detailed observations of a strongly lensed, low-mass (≈107.6 M ⊙) galaxy at z = 3.98 (also see Vanzella et al.). We identify strong narrow nebular emission, including C iv λ λ1548, 1550, He ii λ1640, O iii] λ λ1661, 1666, [Ne iii] λ3868, [O ii] λ3727, and the Balmer series of hydrogen from this galaxy, indicating a metal-poor H ii region (≲0.12 Z ⊙) powered by massive stars. Further, we detect a metal-enriched damped Lyα system (DLA) associated with the galaxy with the H i column density of N H I ≈ 1021.8 cm−2. The metallicity of the associated DLA may reach the supersolar metallicity (≳Z ⊙). Moreover, thanks to JWST and gravitational lensing, we present the resolved UV slope (β) map at the spatial resolution of ≈100 pc at z = 4, with steep UV slopes reaching β ≈ −2.5 around three star-forming clumps. Combining with low-redshift analogs, our observations suggest that low-mass, low-metallicity galaxies, which dominate reionization, could be surrounded by a high covering fraction of the metal-enriched, neutral-gaseous clouds. This implies that the metal enrichment of low-mass galaxies is highly efficient, and further supports that in low-mass galaxies, only a small fraction of ionizing radiation can escape through the interstellar or circumgalactic channels with low-column-density neutral gas.
Author
Xiaojing Lin
Tsinghua University
Zheng Cai
Tsinghua University
Siwei Zou
Tsinghua University
Zihao Li
Tsinghua University
Zuyi Chen
University of Arizona
Fuyan Bian
European Southern Observatory Santiago
Fengwu Sun
University of Arizona
Yiping Shu
Chinese Academy of Sciences
Yunjing Wu
Tsinghua University
University of Arizona
Mingyu Li
Tsinghua University
Jianan Li
Tsinghua University
Xiaohui Fan
University of Arizona
J. Xavier Prochaska
Lick Observatory
University of Tokyo
D. Schaerer
University of Geneva
Stephane Charlot
Institut d 'Astrophysique de Paris
D. Espada
Universidad de Granada
M. Dessauges-Zavadsky
University of Geneva
Eiichi Egami
University of Arizona
Daniel Stark
University of Arizona
Kirsten Knudsen
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Gustavo Bruzual
Universidad Nacional Autónoma de México
Jacopo Chevallard
University of Oxford
Astrophysical Journal Letters
2041-8205 (ISSN) 2041-8213 (eISSN)
Vol. 944 2 L59Subject Categories
Analytical Chemistry
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.3847/2041-8213/aca1c4