{
  "abstract": "In this work, we study the polar perturbations of static, spherically symmetric neutron stars with anisotropic pressure in full general relativity, including linear-order perturbations of both the metric and the fluid. We calculate the $f$-mode frequencies and the corresponding damping times using a consistent treatment of the perturbation of the radial vector $k^α$. In particular, its Lagrangian perturbation $Δk^α$ is determined by the metric perturbations and the fluid Lagrangian displacement and is constrained to the $(\\tilde{u},\\tilde{k})$ plane, where $\\tilde{u}^α$ is the normalized fluid four-velocity. This constraint introduces an additional dynamical degree of freedom into the perturbation equations. Considering three equations of state and the Horvat and Bowers-Liang prescriptions for pressure anisotropy, we find that the $f$-mode frequency increases with stellar mass, ranging from $1$ to $3$~kHz, while the damping time decreases, ranging from $0.5$ to $1.25$~s. Increasing anisotropy, in the sense of tangential pressure exceeding radial pressure, generally lowers the oscillation frequency, while its effect on the damping time depends on the anisotropy prescription: the damping time decreases with increasing anisotropy for the Horvat model but increases with increasing anisotropy for the Bowers-Liang model. We further find quasi-universal relations between the real and imaginary parts of the $f$-mode frequency, $Mω_R$ and $Mω_I$, and the stellar compactness $\\mathcal{C}=M/R$, which are largely insensitive to the equation of state. Polynomial fits to these relations achieve an accuracy better than $10\\%$, providing a simple phenomenological framework for constraining neutron-star pressure anisotropy through future asteroseismology observations.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.07878",
  "author_total": 4,
  "authors": [
    {
      "name": "L. M. Becerra"
    },
    {
      "name": "José F. Rodríguez-Ruiz"
    },
    {
      "name": "E. A. Becerra-Vergara"
    },
    {
      "name": "F. D. Lora-Clavijo"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bqwyz2d1pw2g9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.07878",
  "fulltext_url": null,
  "id": "bqwyz2d1pw2g9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.07878",
  "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",
      "astro-ph.SR"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "openalex",
      "3103|Pulsars and Gravitational Waves Research"
    ]
  ],
  "openalex": "W7212015845",
  "pdf_url": "https://arxiv.org/pdf/2609.07878",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bqwyz2d1pw2g9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.07878",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.07878"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Nonradial oscillations of realistic anisotropic neutron stars: Polar modes",
  "title_text": "Nonradial oscillations of realistic anisotropic neutron stars: Polar modes",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/bqwyz2d1pw2g9",
  "venue": "arXiv",
  "versions": []
}