{
  "abstract": "The angular structure and temporal variability of neutrino emission from binary neutron star mergers are characterized using fully general-relativistic simulations with energy-integrated M1 neutrino transport across a representative set of equations of state, total masses and mass ratios. The main analysis is restricted to merger remnants that do not collapse to a black hole within the simulated time intervals. The angle-dependent neutrino energy flux is extracted on a spherical surface outside the remnant and decomposed into spherical harmonics to quantify its multipolar content and evolution. Following the initial post-merger transient, the neutrino radiation flux approaches an axisymmetric configuration dominated by a strong quadrupolar component, producing persistent polar flux enhancement and equatorial suppression due to torus shadowing. The dipolar contribution remains subdominant, indicating the absence of sustained one-sided emission. The degree of anisotropy increases with mass asymmetry and for softer equations of state, reflecting the compactness and morphology of the remnant--disk system. Superimposed on this time-averaged geometry, coherent azimuthal modulations associated with the $m=1$ mode are identified. The associated half frequency, $f_{\\mathrm{dom}}/2\\simeq0.6$--$0.7\\,\\mathrm{kHz}$, is compared with local rotation rates in the simulated remnant--disk systems, suggesting a possible dynamical association between the remnant structure and neutrino variability. Finally, we quantify how the same quadrupole-dominated radiation geometry induces a latitude-dependent equilibrium electron fraction. The polar material is driven close to the neutrino-equilibrium target, whereas equatorial material remains systematically more neutron rich and below equilibrium.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.16275",
  "author_total": 4,
  "authors": [
    {
      "name": "Kutay Arınç Çokluk"
    },
    {
      "name": "Albino Perego"
    },
    {
      "name": "Federico Maria Guercilena"
    },
    {
      "name": "Kadri Yakut"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/e1w2k44f6vcpn.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.16275",
  "fulltext_url": null,
  "id": "e1w2k44f6vcpn",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.16275",
  "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.HE"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2608.16275",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/e1w2k44f6vcpn.ris",
  "sources": [
    {
      "first_seen": "2026-11-04T15:21:24Z",
      "native_id": "2608.16275",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.16275"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Multipolar neutrino radiation in binary neutron star mergers: Angular structure, rotational variability, and implications for electron fraction",
  "title_text": "Multipolar neutrino radiation in binary neutron star mergers: Angular structure, rotational variability, and implications for electron fraction",
  "type": "preprint",
  "updated_at": "2026-11-06T18:21:01Z",
  "url": "https://research.draconitic.com/paper/e1w2k44f6vcpn",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1103/8nrw-sw93",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}