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首页|RIOJA. JWST and ALMA unveil the inhomogeneous and complex ISM structure in a star-forming galaxy at $z=6.81$

RIOJA. JWST and ALMA unveil the inhomogeneous and complex ISM structure in a star-forming galaxy at $z=6.81$

RIOJA. JWST and ALMA unveil the inhomogeneous and complex ISM structure in a star-forming galaxy at $z=6.81$

来源:Arxiv_logoArxiv
英文摘要

We report the discovery of a complex, two-phase ionized gas structure in the star-forming galaxy COS-2987 at $z = 6.81$, revealed by the unprecedented synergy between JWST/NIRSpec IFS and ALMA observations. These observations detect key emission lines, including [OII]$λλ$ 3727, 3730, [OIII] 4364, [OIII] $λλ$ 4960, 5008, [OIII] 88 $μ$m, as well as H$α$ and H$β$. JWST spectroscopy alone indicates interstellar medium (ISM) properties that are typical for galaxies at $z\sim7$. These include low dust extinction ($A_{\rm V} \approx 0.14$ mag), moderate electron density ($n_{\rm e} \approx 500$ cm$^{-3}$), and low gas-phase metallicity ($\sim10\%$). However, the strong far-infrared [OIII] 88 $μ$m emission detected by ALMA cannot be explained by a single-phase ionized medium with uniform electron density and temperature. Instead, a two-phase ISM model, comprising compact, high-temperature, high-density gas components ($T_e \approx 26,000$ K; $n_e \approx 600 \mathrm{cm}^{-3}$) and an extended, cooler, lower-density component ($T_e \approx 8,000$ K; $n_e \approx 50 \mathrm{cm}^{-3}$), successfully reproduces the observed line ratios of [OIII] 88 $μ$m/[OIII] 5008 Å and [OIII] 4364 Å/[OIII] 5008 Å, with a volume ratio of 1 : 300 between the two phases. Our results demonstrate that JWST alone probes only a fraction of the ISM and highlight the critical importance of combining JWST and ALMA to reveal the density-stratified ISM of early galaxies.

Mitsutaka Usui、Ken Mawatari、Javier Álvarez-Márquez、Takuya Hashimoto、Yuma Sugahara、Rui Marques-Chaves、Akio K. Inoue、Luis Colina、Santiago Arribas、Carmen Blanco-Prieto、Yurina Nakazato、Naoki Yoshida、Tom J. L. C. Bakx、Daniel Ceverino、Luca Costantin、Alejandro Crespo Gómez、Masato Hagimoto、Hiroshi Matsuo、Wataru Osone、Yi W. Ren、Yoshinobu Fudamoto、Takeshi Hashigaya、Miguel Pereira-Santaella、Yoichi Tamura

天文学

Mitsutaka Usui,Ken Mawatari,Javier Álvarez-Márquez,Takuya Hashimoto,Yuma Sugahara,Rui Marques-Chaves,Akio K. Inoue,Luis Colina,Santiago Arribas,Carmen Blanco-Prieto,Yurina Nakazato,Naoki Yoshida,Tom J. L. C. Bakx,Daniel Ceverino,Luca Costantin,Alejandro Crespo Gómez,Masato Hagimoto,Hiroshi Matsuo,Wataru Osone,Yi W. Ren,Yoshinobu Fudamoto,Takeshi Hashigaya,Miguel Pereira-Santaella,Yoichi Tamura.RIOJA. JWST and ALMA unveil the inhomogeneous and complex ISM structure in a star-forming galaxy at $z=6.81$[EB/OL].(2025-07-02)[2025-07-16].https://arxiv.org/abs/2507.02054.点此复制

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