_version_ 1866910307063955456
author Fujimoto, Seiji
Ouchi, Masami
Nakajima, Kimihiko
Harikane, Yuichi
Isobe, Yuki
Brammer, Gabriel
Oguri, Masamune
Giménez-Arteaga, Clara
Heintz, Kasper E.
Kokorev, Vasily
Bauer, Franz E.
Ferrara, Andrea
Kojima, Takashi
Lagos, Claudia del P.
Laura, Sommovigo
Schaerer, Daniel
Shimasaku, Kazuhiro
Hatsukade, Bunyo
Kohno, Kotaro
Sun, Fengwu
Valentino, Francesco
Watson, Darach
Fudamoto, Yoshinobu
Inoue, Akio K.
González-López, Jorge
Koekemoer, Anton M.
Knudsen, Kirsten
Lee, Minju M.
Magdis, Georgios E.
Richard, Johan
Strait, Victoria B.
Sugahara, Yuma
Tamura, Yoichi
Toft, Sune
Umehata, Hideki
Walth, Gregory
author_facet Fujimoto, Seiji
Ouchi, Masami
Nakajima, Kimihiko
Harikane, Yuichi
Isobe, Yuki
Brammer, Gabriel
Oguri, Masamune
Giménez-Arteaga, Clara
Heintz, Kasper E.
Kokorev, Vasily
Bauer, Franz E.
Ferrara, Andrea
Kojima, Takashi
Lagos, Claudia del P.
Laura, Sommovigo
Schaerer, Daniel
Shimasaku, Kazuhiro
Hatsukade, Bunyo
Kohno, Kotaro
Sun, Fengwu
Valentino, Francesco
Watson, Darach
Fudamoto, Yoshinobu
Inoue, Akio K.
González-López, Jorge
Koekemoer, Anton M.
Knudsen, Kirsten
Lee, Minju M.
Magdis, Georgios E.
Richard, Johan
Strait, Victoria B.
Sugahara, Yuma
Tamura, Yoichi
Toft, Sune
Umehata, Hideki
Walth, Gregory
contents We present ALMA deep spectroscopy for a lensed galaxy at $z_{\rm spec}=8.496$ with $\log(M_{\rm star}/M_{\odot})\sim7.8$ whose optical nebular lines and stellar continuum are detected by JWST/NIRSpec and NIRCam Early Release Observations in SMACS0723. Our ALMA spectrum shows [OIII]88$μ$m and [CII]158$μ$m line detections at $4.0σ$ and $4.5σ$, respectively. The redshift and position of the [OIII] line coincide with those of the JWST source, while the [CII] line is blue-shifted by 90 km s$^{-1}$ with a spatial offset of $0.''5$ ($\approx0.5$ kpc in source plane) from the JWST source. The NIRCam F444W image, including [OIII]$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 whose oxygen and carbon produce the extended [OIII]$λ$5007 and the offset [CII] emission, which would promote ionizing photon escape and facilitate reionization. With careful slit-loss corrections and removals of emission spatially outside the galaxy, we evaluate the [OIII]88$μ$m/$λ$5007 line ratio, and derive the electron density $n_{\rm e}$ by photoionization modeling to be $220^{+170}_{-100}$ cm$^{-3}$, which is comparable with those of $z\sim2-3$ galaxies. We estimate an [OIII]88$μ$m/[CII]158$μ$m line ratio in the galaxy of $>4$, as high as those of known $z\sim6-9$ galaxies. This high [OIII]88$μ$m/[CII]158$μ$m line ratio is generally explained by the high $n_{\rm e}$ as well as the low metallicity ($Z_{\rm gas}/Z_{\odot}=0.04^{+0.02}_{-0.02}$), 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 [CII] follow-up observations will constrain the covering fraction of photodissociation regions.
format Preprint
id arxiv_https___arxiv_org_abs_2212_06863
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle JWST and ALMA Multiple-Line Study in and around a Galaxy at $z=8.496$: Optical to FIR Line Ratios and the Onset of an Outflow Promoting Ionizing Photon Escape
Fujimoto, Seiji
Ouchi, Masami
Nakajima, Kimihiko
Harikane, Yuichi
Isobe, Yuki
Brammer, Gabriel
Oguri, Masamune
Giménez-Arteaga, Clara
Heintz, Kasper E.
Kokorev, Vasily
Bauer, Franz E.
Ferrara, Andrea
Kojima, Takashi
Lagos, Claudia del P.
Laura, Sommovigo
Schaerer, Daniel
Shimasaku, Kazuhiro
Hatsukade, Bunyo
Kohno, Kotaro
Sun, Fengwu
Valentino, Francesco
Watson, Darach
Fudamoto, Yoshinobu
Inoue, Akio K.
González-López, Jorge
Koekemoer, Anton M.
Knudsen, Kirsten
Lee, Minju M.
Magdis, Georgios E.
Richard, Johan
Strait, Victoria B.
Sugahara, Yuma
Tamura, Yoichi
Toft, Sune
Umehata, Hideki
Walth, Gregory
Astrophysics of Galaxies
We present ALMA deep spectroscopy for a lensed galaxy at $z_{\rm spec}=8.496$ with $\log(M_{\rm star}/M_{\odot})\sim7.8$ whose optical nebular lines and stellar continuum are detected by JWST/NIRSpec and NIRCam Early Release Observations in SMACS0723. Our ALMA spectrum shows [OIII]88$μ$m and [CII]158$μ$m line detections at $4.0σ$ and $4.5σ$, respectively. The redshift and position of the [OIII] line coincide with those of the JWST source, while the [CII] line is blue-shifted by 90 km s$^{-1}$ with a spatial offset of $0.''5$ ($\approx0.5$ kpc in source plane) from the JWST source. The NIRCam F444W image, including [OIII]$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 whose oxygen and carbon produce the extended [OIII]$λ$5007 and the offset [CII] emission, which would promote ionizing photon escape and facilitate reionization. With careful slit-loss corrections and removals of emission spatially outside the galaxy, we evaluate the [OIII]88$μ$m/$λ$5007 line ratio, and derive the electron density $n_{\rm e}$ by photoionization modeling to be $220^{+170}_{-100}$ cm$^{-3}$, which is comparable with those of $z\sim2-3$ galaxies. We estimate an [OIII]88$μ$m/[CII]158$μ$m line ratio in the galaxy of $>4$, as high as those of known $z\sim6-9$ galaxies. This high [OIII]88$μ$m/[CII]158$μ$m line ratio is generally explained by the high $n_{\rm e}$ as well as the low metallicity ($Z_{\rm gas}/Z_{\odot}=0.04^{+0.02}_{-0.02}$), 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 [CII] follow-up observations will constrain the covering fraction of photodissociation regions.
title JWST and ALMA Multiple-Line Study in and around a Galaxy at $z=8.496$: Optical to FIR Line Ratios and the Onset of an Outflow Promoting Ionizing Photon Escape
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2212.06863