_version_ 1866910904222744576
author Fudamoto, Yoshinobu
Inoue, Akio K.
Bouwens, Rychard
Inami, Hanae
Smit, Renske
Stark, Dan
Aravena, Manuel
Pallottini, Andrea
Hashimoto, Takuya
Oguri, Masamune
Bowler, Rebecca A. A.
da Cunha, Elisabete
Dayal, Pratika
Ferrara, Andrea
Fujimoto, Seiji
Heintz, Kasper E.
Hygate, Alexander P. S.
van Leeuwen, Ivana F.
De Looze, Ilse
Rowland, Lucie E.
Stefanon, Mauro
Sugahara, Yuma
Witstok, Joris
van der Werf, Paul P.
author_facet Fudamoto, Yoshinobu
Inoue, Akio K.
Bouwens, Rychard
Inami, Hanae
Smit, Renske
Stark, Dan
Aravena, Manuel
Pallottini, Andrea
Hashimoto, Takuya
Oguri, Masamune
Bowler, Rebecca A. A.
da Cunha, Elisabete
Dayal, Pratika
Ferrara, Andrea
Fujimoto, Seiji
Heintz, Kasper E.
Hygate, Alexander P. S.
van Leeuwen, Ivana F.
De Looze, Ilse
Rowland, Lucie E.
Stefanon, Mauro
Sugahara, Yuma
Witstok, Joris
van der Werf, Paul P.
contents We present results of new observations of [OI]145um and [NII]205um emission lines from four star-forming galaxies at redshifts between $z=6.58$ and $7.68$ that have previous detections of \Ciium\ and dust continua. Using ALMA, we successfully detect [OI]145um emission from all targets at $>4\,σ$ significance. However, [NII]205um emission is undetected in all galaxies (SNR $<3.5\,σ$) except for a tentative detection from A1689-zD1. From the observed high [CII]/[NII] emission line ratios ($\gtrsim20 - 80$), we find that most of the [CII]158um emission arise from neutral gas regions ($3\,σ$ lower limits of $\gtrsim 74 - 96\%$). From [OI]145um, [CII]158um lines, and infrared luminosities, we estimate the neutral gas densities of $n_{\rm H}=10^{3.5}$ - $10^6\,{\rm cm^{-3}}$ and the far-ultraviolet (FUV) radiation strengths of $G_0\sim10^{2.5}$-$10^{3}$. While the neutral gas densities are similar to those of high-redshift starburst galaxies, the FUV strengths are lower compared to both local and high-redshift starbursts. Finally, we estimate atomic hydrogen masses using [OI]145um emission lines and the oxygen abundances measured from recent JWST observations. We find gas mass ratios of $f_{\rm gas}\sim0.3$ - $0.8$, which are similar to earlier studies using [CII]158um. Starting from this pilot observation, future large [OI]145um emission line surveys will provide us with currently little-known neutral gas properties of star-forming galaxies in the early Universe.
format Preprint
id arxiv_https___arxiv_org_abs_2504_03831
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle ALMA Observations of [OI]145um and [NII]205um Emission lines from Star-Forming Galaxies at $z\sim7$
Fudamoto, Yoshinobu
Inoue, Akio K.
Bouwens, Rychard
Inami, Hanae
Smit, Renske
Stark, Dan
Aravena, Manuel
Pallottini, Andrea
Hashimoto, Takuya
Oguri, Masamune
Bowler, Rebecca A. A.
da Cunha, Elisabete
Dayal, Pratika
Ferrara, Andrea
Fujimoto, Seiji
Heintz, Kasper E.
Hygate, Alexander P. S.
van Leeuwen, Ivana F.
De Looze, Ilse
Rowland, Lucie E.
Stefanon, Mauro
Sugahara, Yuma
Witstok, Joris
van der Werf, Paul P.
Astrophysics of Galaxies
We present results of new observations of [OI]145um and [NII]205um emission lines from four star-forming galaxies at redshifts between $z=6.58$ and $7.68$ that have previous detections of \Ciium\ and dust continua. Using ALMA, we successfully detect [OI]145um emission from all targets at $>4\,σ$ significance. However, [NII]205um emission is undetected in all galaxies (SNR $<3.5\,σ$) except for a tentative detection from A1689-zD1. From the observed high [CII]/[NII] emission line ratios ($\gtrsim20 - 80$), we find that most of the [CII]158um emission arise from neutral gas regions ($3\,σ$ lower limits of $\gtrsim 74 - 96\%$). From [OI]145um, [CII]158um lines, and infrared luminosities, we estimate the neutral gas densities of $n_{\rm H}=10^{3.5}$ - $10^6\,{\rm cm^{-3}}$ and the far-ultraviolet (FUV) radiation strengths of $G_0\sim10^{2.5}$-$10^{3}$. While the neutral gas densities are similar to those of high-redshift starburst galaxies, the FUV strengths are lower compared to both local and high-redshift starbursts. Finally, we estimate atomic hydrogen masses using [OI]145um emission lines and the oxygen abundances measured from recent JWST observations. We find gas mass ratios of $f_{\rm gas}\sim0.3$ - $0.8$, which are similar to earlier studies using [CII]158um. Starting from this pilot observation, future large [OI]145um emission line surveys will provide us with currently little-known neutral gas properties of star-forming galaxies in the early Universe.
title ALMA Observations of [OI]145um and [NII]205um Emission lines from Star-Forming Galaxies at $z\sim7$
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2504.03831