{
  "id": "2001.10668",
  "version": "v1",
  "published": "2020-01-29T02:37:34.000Z",
  "updated": "2020-01-29T02:37:34.000Z",
  "title": "The impact of isomers on a kilonova associated with neutron star mergers",
  "authors": [
    "Shin-ichiro Fujimoto",
    "Masa-aki Hashimoto"
  ],
  "comment": "6 pages, 4 figures. Accepted for publication in MNRAS",
  "categories": [
    "astro-ph.HE",
    "nucl-th"
  ],
  "abstract": "We investigate the significance of isomers on a kilonova associated with neutron star mergers (NSMs) for the first time. We calculate the evolution of abundances and energy generation rates ($\\dot{\\epsilon}_{\\rm nuc}$) of ejecta from NSMs, taking into account $\\beta^-$ decay through isomers. We find that for ejecta with electron fraction ($Y_e$) of $0.2-0.3$, $\\dot{\\epsilon}_{\\rm nuc}$ is appreciably changed from those without isomers, due to the large change in timing of $\\beta^-$ decay through the isomeric states of ${}^{123, 125, 127} \\rm Sn$ and ${}^{128} \\rm Sb$. In particular, the effects of the isomers on $\\dot{\\epsilon}_{\\rm nuc}$ are prominent for ejecta of $Y_e \\sim 0.25$, which could emit a fraction of an early, blue component of a kilonova observed in GW170817. When the excitation from a ground state to its isomeric state is important, the isomers of ${}^{129} \\rm Sb$ and ${}^{129, 131} \\rm Te$ also cause additional and appreciable change in $\\dot{\\epsilon}_{\\rm nuc}$. Furthermore, we demonstrate that larger amounts of lanthanide-free ejecta result in a better fit of an observed light curve of the kilonova in GW170817 if the isomers are taken into account.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-01-29T02:37:34.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "neutron star mergers",
      "isomeric state",
      "lanthanide-free ejecta result",
      "energy generation rates",
      "larger amounts"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}