{
  "abstract": "Understanding how the first galaxies assembled their stellar mass at cosmic dawn is a central frontier of modern astrophysics. JWST has now revealed an unexpected population of ultraviolet-bright galaxies at z>10, whose intense emission points towards a rapid stellar mass growth that challenges current models of early galaxy assembly. Yet, the cold gas fueling this growth remains hidden: current ALMA sensitivity restricts routine detection to only the brightest ionized-gas tracers such as [OIII] 88$μ$m, while [CII] 158$μ$m, a key coolant and gas-mass proxy of the neutral interstellar medium (ISM), is undetected beyond $z\\sim8$. This leaves fundamental questions unanswered: how quickly primeval galaxies gathered cold gas and turned it into stars; what physical conditions (density, temperature, radiation field) characterized their ISM; how fast metals and dust built up; and how feedback regulated early gas assembly. Only a transformational sub-millimeter facility like ALMA2040 can address these questions, enabling systematic surveys of [CII] in the first galaxies and providing a representative census of gas fractions and depletion times. A simulated galaxy at $z=11.3$ shows that ALMA2040 not only will detect, but also spatially resolve its merging cold-gas structure in [CII] on $\\sim$200 pc scales in 5 hours (below 100 pc in 10 hours). ALMA2040 will also spectrally resolve multiple lines simultaneously, akin to integral-field spectroscopy, providing the key diagnostics needed to break density-metallicity-radiation-field degeneracies and map the multi-phase ISM of z>10 galaxies. The combination of dramatically increased line sensitivity and wide instantaneous bandwidth will push the search for the first galaxies out to the earliest cosmic times, with [OIII] detectable up to $z\\sim20$. ALMA2040 will thus be transformative for understanding how the first galaxies assembled at cosmic dawn.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.20733",
  "author_total": 59,
  "authors": [
    {
      "name": "Livia Vallini"
    },
    {
      "name": "Tanio Diaz Santos"
    },
    {
      "name": "Belen Alcalde Pampliega"
    },
    {
      "name": "Hiddo Algera"
    },
    {
      "name": "Manuel Aravena"
    },
    {
      "name": "Cecilia Bacchini"
    },
    {
      "name": "Tom Bakx"
    },
    {
      "name": "Maruša Bradač"
    },
    {
      "name": "Leindert A. Boogaard"
    },
    {
      "name": "Karina I. Caputi"
    },
    {
      "name": "Stefano Carniani"
    },
    {
      "name": "Karin Cescon"
    },
    {
      "name": "Francoise Combes"
    },
    {
      "name": "Carla Cornil-Baïotto"
    },
    {
      "name": "Pierre Cox"
    },
    {
      "name": "Elisabete Da Cunha"
    },
    {
      "name": "Roberto Decarli"
    },
    {
      "name": "Miroslava Dessauges-Zavadsky"
    },
    {
      "name": "Andreas L. Faisst"
    },
    {
      "name": "Roman Fernandez Aranda"
    },
    {
      "name": "Andrea Ferrara"
    },
    {
      "name": "Jonathan Freundlich"
    },
    {
      "name": "Yoshinobu Fudamoto"
    },
    {
      "name": "Seiji Fujimoto"
    },
    {
      "name": "Carlotta Gruppioni"
    },
    {
      "name": "Takuya Hashimoto"
    },
    {
      "name": "Natsuki Hayatsu"
    },
    {
      "name": "Kasper E. Heintz"
    },
    {
      "name": "Jacqueline Hodge"
    },
    {
      "name": "Ryota Ikeda"
    },
    {
      "name": "Gareth C. Jones"
    },
    {
      "name": "Mahsa Kohandel"
    },
    {
      "name": "Adarsh Kumar"
    },
    {
      "name": "Alvaro Labiano"
    },
    {
      "name": "Ivanna Langan"
    },
    {
      "name": "Andrea Lapi"
    },
    {
      "name": "Umberto Maio"
    },
    {
      "name": "Marcella Massardi"
    },
    {
      "name": "Dieu D. Nguyen"
    },
    {
      "name": "Andrea Pallottini"
    },
    {
      "name": "Mamta Pandey-Pommier"
    },
    {
      "name": "Miguel Pereira-Santaella"
    },
    {
      "name": "Gergö Popping"
    },
    {
      "name": "Francesca Pozzi"
    },
    {
      "name": "Prachi Prajapati"
    },
    {
      "name": "Dominik A. Riechers"
    },
    {
      "name": "Francesca Rizzo"
    },
    {
      "name": "Lucie Rowland"
    },
    {
      "name": "Sander Schouws"
    },
    {
      "name": "Irene Shivaei"
    },
    {
      "name": "Laura Sommovigo"
    },
    {
      "name": "Yuma Sugahara"
    },
    {
      "name": "Hannah R. Stacey"
    },
    {
      "name": "Sandro Tacchella"
    },
    {
      "name": "Eros Vanzella"
    },
    {
      "name": "Enrico Veraldi"
    },
    {
      "name": "Julie Wardlow"
    },
    {
      "name": "Joris Witstok"
    },
    {
      "name": "Anita Zanella"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9dzn8eazdgzat.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.20733",
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  "landing_url": "https://arxiv.org/abs/2610.20733",
  "language": null,
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  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
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      "arxiv",
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    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
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  ],
  "openalex": "W7222711180",
  "pdf_url": "https://arxiv.org/pdf/2610.20733",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9dzn8eazdgzat.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:52Z",
      "native_id": "2610.20733",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.20733"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "The dawn of the first galaxies",
  "title_text": "The dawn of the first galaxies",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:41Z",
  "url": "https://research.draconitic.com/paper/9dzn8eazdgzat",
  "venue": "arXiv",
  "versions": []
}