| Autor: |
Seiji Fujimoto, Masami Ouchi, Kimihiko Nakajima, Yuichi Harikane, Yuki Isobe, Gabriel Brammer, Masamune Oguri, Clara Giménez-Arteaga, Kasper E. Heintz, Vasily Kokorev, Franz E. Bauer, Andrea Ferrara, Takashi Kojima, Claudia del P. Lagos, Sommovigo Laura, Daniel Schaerer, Kazuhiro Shimasaku, Bunyo Hatsukade, Kotaro Kohno, Fengwu Sun, Francesco Valentino, Darach Watson, Yoshinobu Fudamoto, Akio K. Inoue, Jorge González-López, Anton M. Koekemoer, Kirsten Knudsen, Minju M. Lee, Georgios E. Magdis, Johan Richard, Victoria B. Strait, Yuma Sugahara, Yoichi Tamura, Sune Toft, Hideki Umehata, Gregory Walth |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
The Astrophysical Journal, Vol 964, Iss 2, p 146 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
1538-4357 |
| DOI: |
10.3847/1538-4357/ad235c |
| Popis: |
We present Atacama Large Millimeter/submillimeter Array (ALMA) deep spectroscopy for a lensed galaxy at z _spec = 8.496 with $\mathrm{log}({M}_{\mathrm{star}}/{M}_{\odot })\sim 7.8$ 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 μ m and [C ii ] 158 μ m line detections at 4.0 σ and 4.5 σ , 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 (≈0.5 kpc in the source plane) from the centroid of the JWST source. The NIRCam F444W image, including [O iii ] λ 5007 and H β 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 ] λ 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 μ m/ λ 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 ∼ 2–3 galaxies. We estimate an [O iii ] 88 μ m/[C ii ] 158 μ m line ratio in the galaxy of >4, as high as those of known z ∼ 6–9 galaxies. This high [O iii ] 88 μ m/[C ii ] 158 μ m line ratio is generally explained by the high n _e as well as the low metallicity ( ${Z}_{\mathrm{gas}}/{Z}_{\odot }={0.04}_{-0.02}^{+0.02}$ ), high ionization parameter ( $\mathrm{log}U\gt -2.27$ ), 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. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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