{
  "abstract": "Galaxy size, as defined as the radius at which the stellar surface density reaches $1~\\mathrm{M}_\\odot\\,\\mathrm{pc}^{-2}$ ($R_1$), has been shown to correlate more tightly with stellar mass than the effective radius. Cosmological simulations further predict a tight relation between $R_1$ and dark matter halo mass ($M_{200}$), but this prediction has not yet been tested observationally. We present the first observational test of the predicted $R_1$--$M_{200}$ relation and assess whether galaxy size, defined through $R_1$, can serve as a robust estimator of dark matter halo mass. We analyze galaxies from the SPARC database, combining high-quality rotation curves to infer dark matter halo masses with stellar surface density profiles derived from photometric data to measure $R_1$. We then compare the observed relation with the predictions from state-of-the-art cosmological simulations. We find good agreement between observations and simulations: galaxies follow the same tight $R_1$--$M_{200}$ relation predicted by numerical models across the explored mass range, with low intrinsic scatter. We provide the first observational validation of the $R_1$--$M_{200}$ relation, demonstrating that $R_1$ is a simple, physically motivated, and robust estimator of dark matter halo mass. Because $R_1$ is determined entirely from photometric observations, it provides a tool for inferring halo masses from imaging data alone, with applications to studies of galaxy formation and evolution.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.35366",
  "author_total": 5,
  "authors": [
    {
      "name": "Chris Brook"
    },
    {
      "name": "Arianna di Cintio"
    },
    {
      "name": "Claudio Dalla Vecchia"
    },
    {
      "name": "Salvador Cardona Barrero"
    },
    {
      "name": "Elena Arjona-Gálvez"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/aq6z63knpm3r0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.35366",
  "fulltext_url": null,
  "id": "aq6z63knpm3r0",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.35366",
  "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": "W7223952611",
  "pdf_url": "https://arxiv.org/pdf/2610.35366",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-26",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/aq6z63knpm3r0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2610.35366",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.35366"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Inferring the Total Mass of Galaxy Halos Using Photometry",
  "title_text": "Inferring the Total Mass of Galaxy Halos Using Photometry",
  "type": "preprint",
  "updated_at": "2026-11-06T18:21:01Z",
  "url": "https://research.draconitic.com/paper/aq6z63knpm3r0",
  "venue": "arXiv",
  "versions": []
}