{
  "abstract": "The Tolman surface-brightness test and the angular-size distance-duality test are two complementary probes of the same underlying relation between luminosity and angular-diameter distance, DL = (1 + z)2DA, as holds in any metric theory of gravity where photon number is conserved. Both tests have recently delivered a priori surprising signals: JWST/ASTRODEEP measurements yield a surface brightness scaling with redshift much flatter than the expected value, and ultracompact radio sources also appear to follow a flatter DL/DA scaling with redshift. These results have been suggested to support non-expanding cosmologies, however they are also sensitive to astrophysical and instrumental effects. We test whether these results indicate genuine departures from standard cosmology by forward-modelling observed surface-brightness evolution in the IllustrisTNG cosmological hydrodynamical simulation, with an empirical mock-spectroscopic selection trained on ASTRODEEP. We show that the astrophysical evolution relevant for both tests may be effectively parametrised as a single power-law exponent for the luminosity density as a function of redshift, for which the simulation gives γ = 2.23 ± 0.20 across realistic aperture conventions. This value is approximately sufficient to explain both the Tolman and distance-duality signals within standard cosmology and galaxy formation physics, with a small discrepancy for the latter suggesting that radio AGN evolve slightly more strongly than bright galaxies.",
  "abstract_shown": true,
  "affiliations": [
    "Institute of Cosmology, and Gravitation, University of Portsmouth , Portsmouth PO1 3FX ,",
    "Astrophysics, University of Oxford, Denys Wilkinson Building , Keble Road, Oxford, OX1 3RH ,",
    "Rudolf Peierls Centre for Theoretical Physics , University of Oxford, Parks Road, Oxford OX1 3PU ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Harry Desmond"
    },
    {
      "affs": [
        1
      ],
      "name": "Tariq Yasin",
      "orcid": "0000-0002-6314-1607"
    },
    {
      "affs": [
        1
      ],
      "name": "Richard Stiskalek"
    },
    {
      "affs": [
        2
      ],
      "name": "Sebastian von Hausegger"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f2yara38fr88p.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag2124",
  "fulltext_url": null,
  "id": "f2yara38fr88p",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2124/9013654",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [],
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  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag2124/73135204/stag2124.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-05",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/f2yara38fr88p.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T00:21:01Z",
      "native_id": "10.1093/mnras/stag2124",
      "source": "crossref",
      "url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2124/9013654"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "journal-openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
    }
  ],
  "title": "Forward-modelling the Tolman and distance-duality tests with IllustrisTNG",
  "title_text": "Forward-modelling the Tolman and distance-duality tests with IllustrisTNG",
  "type": "peer-reviewed",
  "updated_at": "2026-11-07T00:21:00Z",
  "url": "https://research.draconitic.com/paper/f2yara38fr88p",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": []
}