{
  "abstract": "The cosmic microwave background birefringence angle $β$ is exactly degenerate with a common instrumental polarization-angle offset. The Minami--Komatsu(MK) likelihood separates these quantities using Galactic foreground polarization, so its inferred detector angles merit a diagnostic that does not reuse the foreground-$EB$ model. We develop a birefringence-blind differential estimator from antisymmetric and symmetric cross-spectra and apply it for the first time as an explicit consistency test of a foreground-assisted birefringence analysis. For a map pair, the common rotation cancels identically and the estimator measures $Δα_{ij}=α_i-α_j$; combining all pairs in a gauge-fixed network reconstructs the observable detector-dependent calibration pattern. Applied to eight Planck NPIPE detector-set maps, the differential reconstruction agrees with the MK pattern, giving $χ^2=8.18$ for seven degrees of freedom (PTE=0.32), with all shared-data residuals below $1.8σ$. Because both reconstructions use the same maps, this is an independent estimator and modeling route rather than an independent-data confirmation. The agreement therefore strengthens confidence in the calibration foundation of the MK-inferred $β$ without providing an independent absolute measurement of it. A conditional common-mode reconstruction gives $β=0.37\\pm0.12^\\circ$. The differential test uses existing data and can serve as a validation layer for future $EB$-based birefringence analyses.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Astrophys. J. Lett. 1009, L12 (2026)",
  "arxiv": "2609.09149",
  "author_total": 3,
  "authors": [
    {
      "name": "Anto I. Lonappan"
    },
    {
      "name": "Brian Keating"
    },
    {
      "name": "Kam Arnold"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3r6ethswdbncw.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.09149",
  "fulltext_url": null,
  "id": "3r6ethswdbncw",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.09149",
  "language": null,
  "licence": "CC0-1.0",
  "licence_label": "CC0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/publicdomain/zero/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "astro-ph.IM"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.09149",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3r6ethswdbncw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:56Z",
      "native_id": "2609.09149",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.09149"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "Differential Polarization Calibration: A Consistency Test for Cosmic Birefringence",
  "title_text": "Differential Polarization Calibration: A Consistency Test for Cosmic Birefringence",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:56Z",
  "url": "https://research.draconitic.com/paper/3r6ethswdbncw",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.3847/2041-8213/aea401",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}