{
  "abstract": "We present a nonparametric determination of spatial curvature using only late-time geometrical probes. Under a Gaussian Process smoothness prior, we jointly constrain the dimensionless expansion history and $Ω_K$, combining three Type Ia Supernovae (SNeIa) samples with either DESI DR2 line-of-sight baryon acoustic oscillations (BAO) or cosmic chronometers (CC) data. From our baseline SNeIa+BAO analyses we find $Ω_K=0.219^{+0.110}_{-0.111}$, $Ω_K=0.330^{+0.098}_{-0.150}$ and $Ω_K=0.260^{+0.124}_{-0.127}$ for the PantheonPlus, DES Dovekie and Union3 SNeIa samples respectively. These nonparametric results mildly favour an open Universe, supporting recent hints in this direction, and improve on the sensitivity of a previous application of the method by up to a factor of $\\sim 2.5$. We find consistent constraints combining SNeIa and CC, whereas restricting SNeIa data to the redshift range covered by BAO somewhat weakens the constraints and shifts the PantheonPlus central value to $Ω_K<0$. Our results depend only on late-time relative distances and expansion rates, making them insensitive to the absolute distance scale calibration, while relying neither on Cosmic Microwave Background data nor on a parametric dark energy model.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.22470",
  "author_total": 5,
  "authors": [
    {
      "name": "Hannah C. Turner"
    },
    {
      "name": "Suhail Dhawan"
    },
    {
      "name": "Sunny Vagnozzi"
    },
    {
      "name": "Alice Townsend"
    },
    {
      "name": "Peter Massey"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/e3x28af5e9988.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.22470",
  "fulltext_url": null,
  "id": "e3x28af5e9988",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.22470",
  "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.CO"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-ph"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7214019298",
  "pdf_url": "https://arxiv.org/pdf/2609.22470",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/e3x28af5e9988.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:24:11Z",
      "native_id": "2609.22470",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.22470"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Stress-testing the spatially flat Universe: nonparametric spatial curvature determination from DESI DR2",
  "title_text": "Stress-testing the spatially flat Universe: nonparametric spatial curvature determination from DESI DR2",
  "type": "preprint",
  "updated_at": "2026-10-30T12:24:11Z",
  "url": "https://research.draconitic.com/paper/e3x28af5e9988",
  "venue": "arXiv",
  "versions": []
}