| Issue |
A&A
Volume 697, May 2025
|
|
|---|---|---|
| Article Number | A174 | |
| Number of page(s) | 25 | |
| Section | Extragalactic astronomy | |
| DOI | https://doi.org/10.1051/0004-6361/202453048 | |
| Published online | 16 May 2025 | |
The [C II] line emission as an interstellar medium probe in the MARIGOLD galaxies
Argelander Institute für Astronomie, Auf dem Hügel 71, D-53121 Bonn, Germany
⋆ Corresponding author: pkhatri@astro.uni-bonn.de
Received:
18
November
2024
Accepted:
25
February
2025
Context. The [C II] fine-structure line at 157.74 μm is one of the brightest far-infrared emission lines in galaxies and an important probe of galaxy properties such as the star formation rate (SFR) and the molecular gas mass (Mmol).
Aims. Using high-resolution numerical simulations, we tested the reliability of the [C II] line as a tracer of Mmol in high-redshift galaxies and investigated secondary dependences of the [C II]−Mmol relation on the SFR and metallicity. We also investigated the time evolution of the [C II] luminosity function (LF) and the relative spatial extent of [C II] emission and star formation.
Methods. We post-processed galaxies from the MARIGOLD cosmological simulations at redshifts 3 ≤ z ≤ 7 to obtain their [C II] emission. These simulations were performed with the sub-grid chemistry model, HYACINTH, to track the non-equilibrium abundances of H2, CO, C and C+ on the fly. Based on a statistical sample of galaxies at these redshifts, we investigated correlations between the [C II] line luminosity (L[C II]) and the SFR, the Mmol, the total gas mass and the metal mass in gas phase (Mmetal).
Results. We find that accounting for secondary dependencies in the L[C II]−Mmol relation improves the Mmol prediction by a factor of 2.3 at all redshifts. Our simulations predict a mild evolution in the slope of the L[C II]−SFR relation (≲0.15 dex) and an increase in the intercept by 0.5 dex in the above redshift range. Among the various galaxy properties we explore, the [C II] emission in our simulated galaxies shows the tightest correlation with Mmetal, indicating the potential of this line to constrain the metallicity of high-redshift galaxies. About 20% (10%) of our simulated galaxies at z = 5 (z = 4) have [C II] emission extending ≥2 times farther than the star formation activity. The [C II] LF evolves rapidly and is always well approximated by a double power law that does not show an exponential cut-off at the bright end. We record a 600-fold increase in the number density of L[C II] ∼ 109 L⊙ emitters in 1.4 Gyr.
Key words: galaxies: evolution / galaxies: high-redshift / galaxies: ISM / galaxies: luminosity function / mass function
© The Authors 2025
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.
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