{
  "abstract": "Ultralight axion-like particles coupled to photons rotate the linear polarization of distant sources. We propose using the three-dimensional two-point correlation of galaxy polarization-rotation angles to measure not only the amplitude of this birefringence field but also its spatial coherence scale. For a nonrelativistic ALP component with an isotropic Gaussian velocity distribution, the equal-time field correlation has an $e^{-1}$ scale $L_{\\rm G}^{\\rm phys}=\\sqrt{6}/(m_a v_a)$, where $v_a$ is the three-dimensional rms ALP velocity dispersion. A detected turnover in the galaxy-pair correlation therefore measures the characteristic momentum scale $m_a v_a$, while the correlation amplitude constrains $g_{aγ}\\sqrt{Ω_a/Ω_{\\rm DM}}$. For a fiducial survey with $10^6$ polarized galaxies over a quarter of the sky to $z=2$ and effective per-galaxy scatter $σ_{\\rm tot}=10^\\circ$, we find $5σ$ sensitivity to sub-degree correlated rotations over $m_a(10^{-3}c/v_a)\\sim10^{-29}$--$10^{-27}\\,{\\rm eV}$, with $σ[\\log_{10}(m_a v_a)]\\lesssim0.1$ for detected signals across much of this range. This provides a geometric late-time probe complementary to CMB birefringence and structure-formation constraints.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2607.12446",
  "author_total": 1,
  "authors": [
    {
      "name": "Yasuo Doi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/48fyech93ecq0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2607.12446",
  "fulltext_url": null,
  "id": "48fyech93ecq0",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2607.12446",
  "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",
      "hep-ph"
    ],
    [
      "openalex",
      "3106|Dark Matter and Cosmic Phenomena"
    ]
  ],
  "openalex": "W7168371691",
  "pdf_url": "https://arxiv.org/pdf/2607.12446",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/48fyech93ecq0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:18Z",
      "native_id": "2607.12446",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2607.12446"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Measuring Ultralight-Axion Coherence with Galaxy Polarization Correlations",
  "title_text": "Measuring Ultralight-Axion Coherence with Galaxy Polarization Correlations",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:18Z",
  "url": "https://research.draconitic.com/paper/48fyech93ecq0",
  "venue": "arXiv",
  "versions": []
}