{
  "id": "2201.03594",
  "version": "v1",
  "published": "2022-01-10T19:03:03.000Z",
  "updated": "2022-01-10T19:03:03.000Z",
  "title": "Characterizing the breakdown of quasi-universality in the post-merger gravitational waves from binary neutron star mergers",
  "authors": [
    "Carolyn A. Raithel",
    "Elias R. Most"
  ],
  "comment": "8 pages, 3 figures. Equal contribution",
  "categories": [
    "astro-ph.HE",
    "gr-qc"
  ],
  "abstract": "The post-merger gravitational wave (GW) emission from a binary neutron star merger is expected to provide exciting new constraints on the dense-matter equation of state (EoS). Such constraints rely, by and large, on the existence of quasi-universal relations, which relate the peak frequencies of the post-merger GW spectrum to properties of the neutron star structure in a model-independent way. In this work, we report on violations of existing quasi-universal relations between the peak spectral frequency, f_2, and the stellar radius, for EoSs models with backwards-bending slopes in their mass-radius relations (such that the radius increases at high masses). The violations are extreme, with variations in f_2 of up to ~600 Hz between EoSs that predict the same radius for a 1.4 M_sun neutron star, but that have significantly different radii at higher masses. Quasi-universality can be restored by adding in a second parameter to the fitting formulae that depends on the slope of the mass-radius curve. We further find strong evidence that quasi-universality is never broken for the radii of very massive stars (with masses 2 M_sun). Both statements imply that f_2 is mainly sensitive to the high-density EoS. Combined with observations of the binary neutron star inspiral, these generalized quasi-universal relations can be used to simultaneously infer the characteristic radius and slope of the neutron star mass-radius relation.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-01-10T19:03:03.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "binary neutron star merger",
      "post-merger gravitational wave",
      "quasi-universality",
      "quasi-universal relations",
      "neutron star mass-radius relation"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}