Issue |
A&A
Volume 685, May 2024
|
|
---|---|---|
Article Number | A30 | |
Number of page(s) | 8 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202346878 | |
Published online | 30 April 2024 |
A high-redshift calibration of the [O I]-to-H I conversion factor in star-forming galaxies
1
Cosmic Dawn Center (DAWN), Denmark
2
Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen N, Denmark
e-mail: sophia.wilson@nbi.ku.dk; keheintz@nbi.ku.dk
3
Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavík, Iceland
4
AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
5
DTU-Space, Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
6
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei Munchen, Germany
7
Department of Astronomy, University of Illinois, 1002 West Green St., Urbana, IL 61801, USA
Received:
12
May
2023
Accepted:
21
December
2023
The assembly and build-up of neutral atomic hydrogen (H I) in galaxies is one of the most fundamental processes in galaxy formation and evolution. Studying this process directly in the early universe is hindered by the weakness of the hyperfine 21-cm H I line transition, impeding direct detections and measurements of the H I gas masses (MHI). Here we present a new method to infer MHI of high-redshift galaxies using neutral, atomic oxygen as a proxy. Specifically, we derive metallicity-dependent conversion factors relating the far-infrared [O I]-63 μm and [O I]-145 μm emission line luminosities and MHI in star-forming galaxies at z ≈ 2 − 6 using gamma-ray bursts (GRBs) as probes. We calibrate the [O I]-to-H I conversion factor relying on a sample of local galaxies with direct measurements of MHI and [O I]-63 μm and [O I]-145 μm line luminosities in addition to the SIGAME hydrodynamical simulation framework at similar epochs (z ≈ 0). We find that the [O I]63 μm-to-H I and [O I]145 μm-to-H I conversion factors, here denoted β[OI]−63 μm and β[OI]−145 μm, respectively, universally appear to be anti-correlated with the gas-phase metallicity. The GRB measurements further predict a mean ratio of L[OI]−63 μm/L[OI]−145 μm = 1.55 ± 0.12 and reveal generally less excited [C II] over [O I] compared to the local galaxy sample. The z ≈ 0 galaxy sample also shows systematically higher β[OI]−63 μm and β[OI]−145 μm conversion factors than the GRB sample, indicating either suppressed [O I] emission in local galaxies likely due to their lower hydrogen densities or more extended, diffuse H I gas reservoirs traced by the H I 21-cm. Finally, we apply these empirical calibrations to the few detections of [O I]-63 μm and [O I]-145 μm line transitions at z ≈ 2 from the literature and further discuss the applicability of these conversion factors to probe the H I gas content in the dense, star-forming interstellar medium (ISM) of galaxies well into the epoch of reionization.
Key words: gamma-ray burst: general / ISM: abundances / galaxies: abundances / galaxies: high-redshift
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.