JWST and ALMA Multiple-line Study in and around a Galaxy at z=8.496: Optical to Far-Infrared Line Ratios and the Onset of an Outflow Promoting Ionizing Photon Escape
Journal article, 2024
We present Atacama Large Millimeter/submillimeter Array (ALMA) deep spectroscopy for a lensed galaxy at z(spec) = 8.496 with log(M-star/M-circle dot) similar to 7.8 whose optical nebular lines and stellar continuum are detected by JWST/NIRSpec and NIRCam Early Release Observations in the field of SMACS J0723.3-7327. Our ALMA spectrum shows [O III] 88 mu m and [C II] 158 mu m line detections at 4.0 sigma and 4.5 sigma, respectively. The redshift and position of the [O III] line coincide with those of the JWST source, while the [C II] line is blueshifted by 90 km s(-1) with a spatial offset of 0.'' 5 (approximate to 0.5 kpc in the source plane) from the centroid of the JWST source. The NIRCam F444W image, including [O III] lambda 5007 and H beta line emission, spatially extends beyond the stellar components by a factor of >8. This indicates that the z = 8.5 galaxy has already experienced strong outflows as traced by extended [O III] lambda 5007 and offset [C II] emission, which would promote ionizing photon escape and facilitate reionization. With careful slit-loss corrections and the removal of emission spatially outside the galaxy, we evaluate the [O III] 88 mu m/lambda 5007 line ratio, and derive the electron density n (e) by photoionization modeling to be 220(-130)(+230) cm(-3), which is comparable with those of z similar to 2-3 galaxies. We estimate an [O III] 88 mu m/[C II] 158 mu m line ratio in the galaxy of >4, as high as those of known z similar to 6-9 galaxies. This high [O III] 88 mu m/[C II] 158 mu m line ratio is generally explained by the high n(e) as well as the low metallicity (Z(gas)/Z(circle dot)=0.04(-0.02)(+0.02)), high ionization parameter (log U > -2.27), and low carbon-to-oxygen abundance ratio (log(C/O) = [-0.52: -0.24]) obtained from the JWST/NIRSpec data; further [C II] follow-up observations will constrain the covering fraction of photodissociation regions.
Author
Seiji Fujimoto
University of Texas
University of Copenhagen
Masami Ouchi
National Astronomical Observatory of Japan
Waseda University
Kimihiko Nakajima
National Astronomical Observatory of Japan
Yuichi Harikane
Waseda University
Yuki Isobe
Waseda University
Gabriel Brammer
University of Copenhagen
Masamune Oguri
Chiba University
Clara Gimenez-Arteaga
University of Copenhagen
Kasper E. Heintz
University of Copenhagen
Vasily Kokorev
University of Copenhagen
Franz E. Bauer
Pontificia Univ Catolica Chile
Millennium Institute of Astrophysics
Andrea Ferrara
Scuola Normale Superiore di Pisa
Takashi Kojima
Waseda University
Claudia del P. Lagos
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)
University of Copenhagen
University of Western Australia
Sommovigo Laura
Scuola Normale Superiore di Pisa
Daniel Schaerer
University of Geneva
Centre national de la recherche scientifique (CNRS)
Kazuhiro Shimasaku
University of Tokyo
Bunyo Hatsukade
University of Tokyo
Kotaro Kohno
University of Tokyo
Fengwu Sun
University of Arizona
Francesco Valentino
University of Copenhagen
European Southern Observatory Santiago
Darach Watson
University of Copenhagen
Yoshinobu Fudamoto
National Astronomical Observatory of Japan
Waseda University
Akio K. Inoue
Waseda University
Jorge Gonzalez-Lopez
Carnegie Institution of Washington
Diego Portales University
Anton M. Koekemoer
Space Telescope Science Institute (STScI)
Kirsten Knudsen
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Minju M. Lee
University of Copenhagen
Technical University of Denmark (DTU)
Georgios E. Magdis
University of Copenhagen
Technical University of Denmark (DTU)
Johan Richard
Université de Lyon
Victoria B. Strait
University of Copenhagen
Yuma Sugahara
Waseda University
National Astronomical Observatory of Japan
Yoichi Tamura
Nagoya University
Sune Toft
University of Copenhagen
Hideki Umehata
Nagoya University
Gregory Walth
California Institute of Technology (Caltech)
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 964 2 146Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.3847/1538-4357/ad235c