{
  "id": "2406.17195",
  "version": "v1",
  "published": "2024-06-25T00:52:15.000Z",
  "updated": "2024-06-25T00:52:15.000Z",
  "title": "Couplings of torsional and shear oscillations in a neutron star crust",
  "authors": [
    "Hajime Sotani",
    "Arthur G. Suvorov",
    "Kostas D. Kokkotas"
  ],
  "comment": "Accepted for publication in RPD",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Mature neutron stars are thought to be sufficiently cold that nuclei in the outer layers freeze, solidifying a crust. Crustal elasticity allows the star to support a set of seismic modes, such as torsional oscillations. These axial-parity modes can couple to the polar sector in a number of ways, for example via rotation or a magnetic field. Even in a static, spherically-symmetric star however these modes can couple at non-linear order. In this study, such couplings in the crust are examined for the first time: we derive the axisymmetric perturbation equations for second-order axial eigenfunctions, which are sourced by axial-polar couplings at first-order, and solve the resulting equations in the time domain. Through our studies, we find that the second-order spectrum contains additional oscillation modes, not predicted by the linear analysis with either axial or polar perturbations, which can be excited to relatively large amplitudes.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-06-25T00:52:15.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "neutron star crust",
      "shear oscillations",
      "second-order spectrum contains additional oscillation",
      "spectrum contains additional oscillation modes"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}