{
  "id": "2008.03335",
  "version": "v1",
  "published": "2020-08-07T18:50:38.000Z",
  "updated": "2020-08-07T18:50:38.000Z",
  "title": "MeV Gamma Rays from Fission: A Distinct Signature of Actinide Production in Neutron Star Mergers",
  "authors": [
    "Xilu Wang",
    "Nicole Vassh",
    "Trevor Sprouse",
    "Matthew Mumpower",
    "Ramona Vogt",
    "Jorgen Randrup",
    "Rebecca Surman"
  ],
  "comment": "8 pages, 5 figures",
  "categories": [
    "astro-ph.HE",
    "nucl-th"
  ],
  "abstract": "Neutron star mergers (NSMs) are the first verified site of rapid neutron capture (r-process) nucleosynthesis, and could emit gamma rays from the radioactive isotopes synthesized in the neutron-rich ejecta. These MeV gamma rays may provide a unique and direct probe of the NSM environment as well insight into the nature of the r process, just as observed gammas from the 56Ni radioactive decay chain provide a window into supernova nucleosynthesis. In this work, we include the photons from fission processes for the first time in estimates of the MeV gamma-ray signal expected from a NSM event. We consider NSM ejecta compositions with a range of neutron richness and find a dramatic difference in the predicted signal depending on whether or not fissioning nuclei are produced. The difference is most striking at photon energies above ~3.5 MeV and at a relatively late time, several days after the merger event, when the ejecta is optically thin. We estimate that a Galactic NSM could be detectable by a next generation gamma-ray detector such as AMEGO in the MeV range, up to ~10^4 days after the merger, if fissioning nuclei are robustly produced in the event.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-08-07T18:50:38.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "neutron star mergers",
      "mev gamma rays",
      "distinct signature",
      "actinide production",
      "emit gamma rays"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 8,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}