{
  "abstract": "We investigate constraints on additional relativistic species and thermal sterile neutrinos using the DESI DR1 one-dimensional Lyman-$α$ forest power spectrum, combined with Planck 2018 CMB and DESI DR2 BAO measurements. We consider both the $Λ$CDM+$N_{\\rm eff}$ extension and a thermal with a different-temperature sterile-neutrino (DTS) scenario, in which the sterile relic can be colder than the standard neutrino background. We first validate the DESI two-parameter $P_{\\rm 1D}$ compression for the DTS model, finding that the residual cosmological dependence not captured by the compressed parameters remains below 0.15%. No significant evidence for additional radiation or a sterile component is found. For $Λ$CDM+$N_{\\rm eff}$, we obtain $N_{\\rm eff}<3.41$ at 95% credibility from CMB+DESI-BAO+DESI-$P_{\\rm 1D}$. In the DTS scenario, the full CMB+DESI-BAO+DESI-$P_{\\rm 1D}$ combination yields the stringent bound $m_s^{\\rm eff}<0.061\\,{\\rm eV}$, highlighting the complementarity of BAO and Lyman-$α$ information in constraining the massive sterile abundance. We further interpret the allowed $ΔN_{\\rm eff}$ in terms of thermal light relics, deriving lower limits on their decoupling temperatures that reach the QCD epoch.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.22581",
  "author_total": 4,
  "authors": [
    {
      "name": "Emanuelly Silva"
    },
    {
      "name": "Artur Ladeira"
    },
    {
      "name": "Rafael C. Nunes"
    },
    {
      "name": "Eleonora Di Valentino"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7ajh68f1mpgsd.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.22581",
  "fulltext_url": null,
  "id": "7ajh68f1mpgsd",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.22581",
  "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",
      "hep-ph"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7214018325",
  "pdf_url": "https://arxiv.org/pdf/2609.22581",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7ajh68f1mpgsd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.22581",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.22581"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Hunting Thermal Relics in the DESI DR1 Ly$α$ Forest",
  "title_text": "Hunting Thermal Relics in the DESI DR1 Lyα Forest",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/7ajh68f1mpgsd",
  "venue": "arXiv",
  "versions": []
}