Compact Ionized Gas Region Surrounded by Porous Neutral Gas in a Dusty Lyman Break Galaxy at Redshift $z=8.312$
Fuente:
arXiv
Salvato in:
| Autori principali: | , , , , , , , , , , , |
|---|---|
| Natura: | Preprint |
| Pubblicazione: |
2025
|
| Soggetti: | |
| Accesso online: | |
| Tags: |
Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
|
| _version_ | 1866916811089379328 |
|---|---|
| author | Hagimoto, Masato Tamura, Yoichi Inoue, Akio K. Umehata, Hideki Bakx, Tom J. L. C. Hashimoto, Takuya Mawatari, Ken Sugahara, Yuma Fudamoto, Yoshinobu Harikane, Yuichi Matsuo, Hiroshi Taniguchi, Akio |
| author_facet | Hagimoto, Masato Tamura, Yoichi Inoue, Akio K. Umehata, Hideki Bakx, Tom J. L. C. Hashimoto, Takuya Mawatari, Ken Sugahara, Yuma Fudamoto, Yoshinobu Harikane, Yuichi Matsuo, Hiroshi Taniguchi, Akio |
| contents | Porous interstellar medium (ISM) structure in galaxies at the epoch of reionization (EoR) gives us a hint to understand what types of galaxies contribute to reionization. Although recent studies have pointed out the positive correlation between high ionizing photon escape fractions and high [O III] $88~μ\mathrm{m}$-to-[C II] $158~μ\mathrm{m}$ ratios found in UV-luminous star-forming galaxies at $z > 6$ with ALMA, previous studies have paid little attention to the neutral gas porosity that allows ionizing photons to escape. Here, we present a detailed analysis of a $z=8.312$ Lyman break galaxy, MACS0416_Y1 with a high $L_\mathrm{[OIII]88}/L_\mathrm{[CII]158}$ ratio ($\approx9$) and dust continuum detection. We construct a multi-phase ISM model incorporating the neutral gas covering fraction ($cov_\mathrm{PDR}$). The best-fit model reveals a $cov_\mathrm{PDR}\approx25 \%$, indicating that $\approx75 \%$ of the ionized gas region is exposed to intercloud space. We confirm that our conclusions hold even when varying star-formation history, stellar age, gas/stellar metallicity, and carbon-to-oxygen abundance ratio. This finding meets one of the necessary conditions for galaxies to have a non-zero escape fraction of ionizing photons and supports recent studies that galaxies with a high [O III] $88~μ\mathrm{m}/$[C II] $158~μ\mathrm{m}$ ratio, such as MACS0416_Y1, could contribute to cosmic reionization. Furthermore, the modeled H II region with the best-fitting parameters has a typical size ($D=0.90~\mathrm{pc}$) and gas density ($\log n_\mathrm{H,c}/\mathrm{cm^{-3}}=2.7$) that are comparable to local compact H II regions. This suggests that the H II regions in MACS0416_Y1 are in an early evolutionary stage. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_20734 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Compact Ionized Gas Region Surrounded by Porous Neutral Gas in a Dusty Lyman Break Galaxy at Redshift $z=8.312$ Hagimoto, Masato Tamura, Yoichi Inoue, Akio K. Umehata, Hideki Bakx, Tom J. L. C. Hashimoto, Takuya Mawatari, Ken Sugahara, Yuma Fudamoto, Yoshinobu Harikane, Yuichi Matsuo, Hiroshi Taniguchi, Akio Astrophysics of Galaxies Porous interstellar medium (ISM) structure in galaxies at the epoch of reionization (EoR) gives us a hint to understand what types of galaxies contribute to reionization. Although recent studies have pointed out the positive correlation between high ionizing photon escape fractions and high [O III] $88~μ\mathrm{m}$-to-[C II] $158~μ\mathrm{m}$ ratios found in UV-luminous star-forming galaxies at $z > 6$ with ALMA, previous studies have paid little attention to the neutral gas porosity that allows ionizing photons to escape. Here, we present a detailed analysis of a $z=8.312$ Lyman break galaxy, MACS0416_Y1 with a high $L_\mathrm{[OIII]88}/L_\mathrm{[CII]158}$ ratio ($\approx9$) and dust continuum detection. We construct a multi-phase ISM model incorporating the neutral gas covering fraction ($cov_\mathrm{PDR}$). The best-fit model reveals a $cov_\mathrm{PDR}\approx25 \%$, indicating that $\approx75 \%$ of the ionized gas region is exposed to intercloud space. We confirm that our conclusions hold even when varying star-formation history, stellar age, gas/stellar metallicity, and carbon-to-oxygen abundance ratio. This finding meets one of the necessary conditions for galaxies to have a non-zero escape fraction of ionizing photons and supports recent studies that galaxies with a high [O III] $88~μ\mathrm{m}/$[C II] $158~μ\mathrm{m}$ ratio, such as MACS0416_Y1, could contribute to cosmic reionization. Furthermore, the modeled H II region with the best-fitting parameters has a typical size ($D=0.90~\mathrm{pc}$) and gas density ($\log n_\mathrm{H,c}/\mathrm{cm^{-3}}=2.7$) that are comparable to local compact H II regions. This suggests that the H II regions in MACS0416_Y1 are in an early evolutionary stage. |
| title | Compact Ionized Gas Region Surrounded by Porous Neutral Gas in a Dusty Lyman Break Galaxy at Redshift $z=8.312$ |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2506.20734 |