{
  "abstract": "In the standard model of cosmology, it is assumed that dark matter is pressureless with equation of state w = 0 and dark energy has w = −1. We test these assumptions jointly using DESI DR2 distance measurements, including the recent Ly α Alcock–Paczynski (AP) information, Dark Energy Survey (DES) supernovae, and two complementary cosmic microwave background (CMB) treatments. When constant w DM and w DE are varied together, we find w DM = 0.00096 8 − 0.000496 + 0.000501 and w DE = − 0.938 0 − 0.0262 + 0.0259 (68%). With an alternative CMB treatment that marginalizes over the lensing spectrum, the corresponding constraints are w DM = 0.00087 0 − 0.000410 + 0.000408 and w DE = − 0.935 3 − 0.0254 + 0.0258 . Both standard ΛCDM values are disfavored at approximately 2 σ in the joint extension. Neither parameter departs significantly from its standard value when only that parameter is varied. This behavior arises because late-time distances favor w DE > −1, while maintaining the early-Universe physical matter density requires a compensating positive w DM , which changes the mapping to the matter density today. Allowing dynamical dark energy further highlights the complexity of the situation: phantom crossing for dark energy makes w DM = 0 consistent with the data, whereas a positive w DM preference persists when crossing is forbidden. Interestingly, the Padé- w parameterization that provides a flexible description of a class of quintessence models (with no phantom crossing), along with w DM free, is even mildly favored over the phantom-crossing w ₀ w a model according to both the best-fit χ ² and the deviance information criterion (DIC) under both CMB treatments. One can conclude that the apparent preference for phantom crossing may instead reflect deviations in the dark-matter sector rather than dark-energy dynamics alone. With future high-redshift distance measurements, particularly improved Ly α observations, together with growth and lensing probes, these possibilities may be further clarified.",
  "abstract_shown": true,
  "affiliations": [
    "Korea Astronomy and Space Science Institute",
    "University of Science and Technology"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 2,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Jun-Qian Jiang",
      "orcid": "0000-0003-0957-3633"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Arman Shafieloo",
      "orcid": "0000-0001-6815-0337"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5wmq5ag0e60sd.bib",
  "cited_by": 0,
  "doi": "10.3847/2041-8213/aeaa2a",
  "fulltext_url": null,
  "id": "5wmq5ag0e60sd",
  "issns": [
    "2041-8205",
    "2041-8213"
  ],
  "landing_url": "https://iopscience.iop.org/article/10.3847/2041-8213/aeaa2a",
  "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|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7196923042",
  "pdf_url": "https://iopscience.iop.org/article/10.3847/2041-8213/aeaa2a/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-07",
  "publisher": "American Astronomical Society",
  "ris": "https://research.draconitic.com/paper/5wmq5ag0e60sd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:13Z",
      "native_id": "10.3847/2041-8213/aeaa2a",
      "source": "crossref",
      "url": "https://iopscience.iop.org/article/10.3847/2041-8213/aeaa2a"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Cosmology and Gravitation Theories",
      "subfield": "cosmology"
    }
  ],
  "title": "Is Dark Matter Really Matter?",
  "title_text": "Is Dark Matter Really Matter?",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:13Z",
  "url": "https://research.draconitic.com/paper/5wmq5ag0e60sd",
  "venue": "The Astrophysical Journal Letters",
  "versions": [
    {
      "doi": "10.48550/arxiv.2608.04763",
      "pid": "cgpn6prjdfx0d",
      "relation": "preprint",
      "title": "Is Dark Matter Really Matter?",
      "venue": "arXiv"
    }
  ]
}