{
  "abstract": "James Webb Space Telescope (JWST) has enabled the detection of galaxies in the earliest stages of cosmic history. We compare the ultraviolet luminosity functions (UVLFs) at redshifts $z=7\\mathrm{-}20$ predicted by a set of new cosmological hydrodynamical simulations, colibre (COLd ISM and Better REsolution), with observations, including those from JWST. The UV luminosities of colibre galaxies are derived using the radiative transfer code skirt, which tracks stellar emission and its processing through the multiphase interstellar medium and dust distribution predicted by colibre. We find that although colibre is consistent with the observed evolution of the stellar mass function up to $z=12$, its dust-attenuated UVLFs fall systematically below the observations at the bright end: at the number density of $10^{-6}\\, \\mathrm{Mpc^{-3}\\, mag^{-1}}$, the brightest galaxies are underluminous by $\\approx 1\\, \\rm mag$ at $z=7$, increasing to $\\approx 2.5\\, \\rm mag$ at $z=15$. Accounting for observational uncertainties brings the colibre UVLFs closer to the observational data, but does not fully resolve the discrepancy. Ignoring dust attenuation allows colibre to produce sufficiently bright galaxies at $7\\lesssim z \\lesssim 12$, but at $z=15$, colibre still underpredicts the luminosities of the brightest galaxies, indicating the need for additional physical mechanisms to boost the UV luminosities at the earliest cosmic epochs, such as a ‘top-heavy’ stellar initial mass function. We fit the colibre UVLFs with Schechter functions and calculate the evolution of the best-fitting parameters. We find that the galaxy number density decreases, the characteristic luminosity becomes fainter and the faint-end slope becomes steeper towards higher redshifts. The UV luminosity density decreases by a factor of several hundred from $z = 7$ to $15$.",
  "abstract_shown": true,
  "affiliations": [
    "Institute for Computational Cosmology, Department of Physics, University of Durham , South Road, Durham DH1 3LE ,",
    "Department of Physics and Astronomy, Universiteit Gent , Proeftuinstraat 86 N3, B-9000 Ghent ,",
    "Leiden Observatory, Leiden University , PO Box 9513, NL-2300 RA Leiden ,",
    "Astrophysics Research Institute, Liverpool John Moores University , 146 Brownlow Hill, Liverpool L3 5RF ,",
    "Dipartimento di Fisica G. Occhialini, Università degli Studi di Milano Bicocca, Piazza della Scienza , 3 I-20126 Milano MI ,",
    "Department of Astrophysics, University of Vienna , Türkenschanzstrasse 17, A-1180 Vienna ,",
    "Centre for Data Science, Artificial Intelligence and Modelling, University of Hull , Cottingham Road, Hull HU6 7RX ,",
    "E. A. Milne Centre for Astrophysics, University of Hull , Cottingham Road, Hull HU6 7RX ,",
    "Lorentz Institute for Theoretical Physics, Leiden University , PO Box 9506, NL-2300 RA Leiden ,",
    "Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire , College Lane, Hatfield, AL10 9AB ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 20,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Shengdong Lu",
      "orcid": "0000-0002-6726-9499"
    },
    {
      "affs": [
        0
      ],
      "name": "Carlos S Frenk",
      "orcid": "0000-0002-2338-716X"
    },
    {
      "affs": [
        0
      ],
      "name": "Cedric G Lacey",
      "orcid": "0000-0001-9016-5332"
    },
    {
      "affs": [
        1
      ],
      "name": "Andrea Gebek",
      "orcid": "0000-0002-0206-8231"
    },
    {
      "affs": [
        2
      ],
      "name": "Joop Schaye",
      "orcid": "0000-0002-0668-5560"
    },
    {
      "affs": [
        0
      ],
      "name": "Shaun Cole",
      "orcid": "0000-0002-5954-7903"
    },
    {
      "affs": [
        0
      ],
      "name": "Sownak Bose",
      "orcid": "0000-0002-0974-5266"
    },
    {
      "affs": [
        3
      ],
      "name": "Anna Durrant",
      "orcid": "0009-0003-9672-2170"
    },
    {
      "affs": [
        1
      ],
      "name": "Nick Andreadis",
      "orcid": "0009-0001-9915-6325"
    },
    {
      "affs": [
        1
      ],
      "name": "Maarten Baes",
      "orcid": "0000-0002-3930-2757"
    },
    {
      "affs": [
        4
      ],
      "name": "Alejandro Benítez-Llambay",
      "orcid": "0000-0001-8261-2796"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Evgenii Chaikin",
      "orcid": "0000-0003-2047-3684"
    },
    {
      "affs": [
        2
      ],
      "name": "Camila Correa",
      "orcid": "0000-0002-5830-8070"
    },
    {
      "affs": [
        3
      ],
      "name": "Robert A Crain",
      "orcid": "0000-0001-6258-0344"
    },
    {
      "affs": [
        2
      ],
      "name": "Filip Huško",
      "orcid": "0000-0002-1510-1731"
    },
    {
      "affs": [
        2
      ],
      "name": "Robert J McGibbon",
      "orcid": "0000-0003-0651-0776"
    },
    {
      "affs": [
        5
      ],
      "name": "Sylvia Ploeckinger",
      "orcid": "0000-0002-1965-1650"
    },
    {
      "affs": [
        6,
        7
      ],
      "name": "Alexander J Richings",
      "orcid": "0000-0003-0502-9235"
    },
    {
      "affs": [
        2,
        8
      ],
      "name": "Matthieu Schaller",
      "orcid": "0000-0002-2395-4902"
    },
    {
      "affs": [
        9
      ],
      "name": "James W Trayford",
      "orcid": "0000-0003-1530-1634"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9f66sya8kh6zt.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag1846",
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    "0035-8711",
    "1365-2966"
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  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
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  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag1846/71532297/stag1846.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-30",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/9f66sya8kh6zt.ris",
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  "subjects": [
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      "field": "astronomy",
      "origin": "openalex:3103|Galaxies: Formation, Evolution, Phenomena",
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  ],
  "title": "The galaxy ultraviolet luminosity function from z = 7 to 20 in the COLIBRE simulations",
  "title_text": "The galaxy ultraviolet luminosity function from z = 7 to 20 in the COLIBRE simulations",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:17Z",
  "url": "https://research.draconitic.com/paper/9f66sya8kh6zt",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": [
    {
      "doi": "10.48550/arxiv.2605.06782",
      "pid": "5nhthywxfvvaj",
      "relation": "preprint",
      "title": "The galaxy ultraviolet luminosity function from $z=7$ to $20$ in the COLIBRE simulations",
      "venue": "arXiv"
    }
  ]
}