{
  "abstract": "Providing robust redshift estimates for almost 3 million luminous red galaxies (LRGs), the Dark Energy Spectroscopic Instrument (DESI) offers a unique opportunity to test the expansion rate of the Universe with independent approaches. We apply the cosmic chronometer method to derive new, independent constraints on the Hubble parameter at 0.3<z<1.2 from the differential age evolution of DESI LRGs. We select spectra applying spectroscopic cuts to ensure sample purity and remove contamination by star-forming objects, then build a robust sample of cosmic chronometers (CCs) by stacking to obtain stable, high signal-to-noise (S/N) spectra, which also serves as a democratic binning choice for the $t-z$ plane. Ages are estimated by measuring Lick indices on the stacked spectra and fitting them with a theoretical stellar population model. We obtain $t-z$ relations from which we derive $H(z)$ constraints via two independent approaches: a fit with a pivotal-redshift cosmography, and a direct estimate from the original CC method. The cosmographic fit yields posteriors for the kinematic parameters $\\{H_{z_0}, q_{z_0}, j_{z_0}\\}$ compatible with currently considered cosmologies, giving a precision-level estimate of $H(z)$. We provide the maximum-a-posteriori (MAP) $H(z)$ estimate, an array of the median confidence region in the $H-z$ plane, and its covariance matrix. We also leverage the redshift distributions of the $t-z$ relation for different velocity dispersion groups to obtain two independent local measurements using the discrete approximation $H(z) \\approx -Δz/[Δt (1+z)]$; the one from the reddest envelope of CCs gives $H(z \\approx 0.61) = 88.5^{+6.7}_{-12.6}$ (stat.) $\\pm 8.1$ (syst.) km s$^{-1}$ Mpc$^{-1}$. Systematic uncertainties for both the cosmographic and discrete $H(z)$ measurements come from a comprehensive analysis of all methodological choices in the data treatment.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.13178",
  "author_total": 9,
  "authors": [
    {
      "name": "Carlos A. Álvarez"
    },
    {
      "name": "Marcos M. Cueli"
    },
    {
      "name": "Balakrishna S. Haridasu"
    },
    {
      "name": "Michele Moresco"
    },
    {
      "name": "Martina Torsello"
    },
    {
      "name": "Alessandro Bressan"
    },
    {
      "name": "Lumen Boco"
    },
    {
      "name": "Luigi Danese"
    },
    {
      "name": "Andrea Lapi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ckc69yc0mv4tk.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.13178",
  "fulltext_url": null,
  "id": "ckc69yc0mv4tk",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.13178",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7203473181",
  "pdf_url": "https://arxiv.org/pdf/2608.13178",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ckc69yc0mv4tk.ris",
  "sources": [
    {
      "first_seen": "2026-11-03T12:20:58Z",
      "native_id": "2608.13178",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.13178"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Cosmography with DESI-DR1 Cosmic Chronometers: Direct H(z) measurements from Luminous Red Galaxy ages",
  "title_text": "Cosmography with DESI-DR1 Cosmic Chronometers: Direct H(z) measurements from Luminous Red Galaxy ages",
  "type": "preprint",
  "updated_at": "2026-11-03T12:20:58Z",
  "url": "https://research.draconitic.com/paper/ckc69yc0mv4tk",
  "venue": "arXiv",
  "versions": []
}