{
  "abstract": "Molecular gas plays a central role in regulating star formation and galaxy evolution, yet observational constraints at cosmic noon remain biased toward massive, metal-rich systems. We present ALMA Band 3 observations of the CO J=3-2 transition in 26 unlensed star-forming galaxies from the ALMA Chemical Evolution (ACE) Large Program at z~2-2.5, probing stellar masses of $10^{9} < M_\\star < 10^{10.5}\\,\\mathrm{M}_{\\odot}$ and sub-solar metallicities (8.2 < 12 + log(O/H) < 8.6). We derived molecular gas masses using a metallicity-dependent CO-to-H$_2$ conversion factor and alongside analysed stacking measurements and a homogenized literature compilation spanning both local and high-redshift galaxies. We find that the ACE galaxies extend established molecular-gas scaling relations to an order of magnitude lower stellar masses than previously explored at cosmic noon. The molecular gas mass ($M_{\\rm mol}$) correlates tightly with star formation rate (SFR), while molecular gas fractions show a strong dependence on specific star formation rate (sSFR) and offset from the star-forming main sequence. In contrast, molecular gas fractions show only weak trends with stellar mass and no significant dependence on metallicity. Molecular gas depletion times are ~1 Gyr and vary little with stellar mass or metallicity, and weakly with sSFR and offset from the star-forming main sequence. Together this further reinforces that the availability of molecular gas is the primary driver of the SFR in galaxies, with changes in star-formation efficiency playing a secondary role. Leveraging the expanded parameter space probed by the ACE and literature samples, we derive a new empirical prescription for predicting $M_{\\rm mol}$ as a function of SFR and sSFR. The persistence of the observed scaling relations suggests a largely universal framework governing the molecular gas-star formation cycle across cosmic time.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.21072",
  "author_total": 16,
  "authors": [
    {
      "name": "Gergő Popping"
    },
    {
      "name": "Ivanna Langan"
    },
    {
      "name": "Nikki N. Geesink"
    },
    {
      "name": "Melanie Kaasinen"
    },
    {
      "name": "Irene Shivaei"
    },
    {
      "name": "Leindert A. Boogaard"
    },
    {
      "name": "Daizhong Liu"
    },
    {
      "name": "Max Parente"
    },
    {
      "name": "Alexandra Pope"
    },
    {
      "name": "Roxana Popescu"
    },
    {
      "name": "Manuel Solimano"
    },
    {
      "name": "Bahram Mobasher"
    },
    {
      "name": "Bianca Moreschini"
    },
    {
      "name": "Desika Narayanan"
    },
    {
      "name": "Naveen Reddy"
    },
    {
      "name": "Ryan L. Sanders"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/09ha5fj08dnx0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.21072",
  "fulltext_url": null,
  "id": "09ha5fj08dnx0",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.21072",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7213924565",
  "pdf_url": "https://arxiv.org/pdf/2609.21072",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/09ha5fj08dnx0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:03Z",
      "native_id": "2609.21072",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.21072"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "ALMA Chemical Evolution (ACE) Survey: Molecular gas properties of low-mass, low-metallicity galaxies at cosmic noon",
  "title_text": "ALMA Chemical Evolution (ACE) Survey: Molecular gas properties of low-mass, low-metallicity galaxies at cosmic noon",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:03Z",
  "url": "https://research.draconitic.com/paper/09ha5fj08dnx0",
  "venue": "arXiv",
  "versions": []
}