{
  "id": "1802.07732",
  "version": "v1",
  "published": "2018-02-21T19:00:02.000Z",
  "updated": "2018-02-21T19:00:02.000Z",
  "title": "Is the macronova in GW170817 powered by the central engine?",
  "authors": [
    "Tatsuya Matsumoto",
    "Kunihito Ioka",
    "Shota Kisaka",
    "Ehud Nakar"
  ],
  "comment": "12 pages, 6 figures, submitted to ApJ, comments welcome!",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "The gravitational wave event GW170817 from a binary neutron star (NS) merger is accompanied by electromagnetic counterparts, and the optical and near-infared emission is called a macronova (or kilonova). Although the radioactivity of synthesized r-process elements is widely discussed as an energy source, its decisive evidence is not clearly shown yet. We discuss a macronova powered by the central engine activities such as jet activities and X-rays from the matter fallback, and show that the engine model allows much broader parameter spaces, in particular smaller ejecta mass ($\\sim10^{-4}-0.01\\,\\Msun$) than the r-process model. The blue and red macronovae are naturally explained by various combinations of the ejecta such as a cocoon and merger ejecta with the energy sources of jets and X-rays. The required energy injection is very similar to the X-ray excess observed in GRB 130603B with the power-law slope of $\\sim-1.3$. The required lanthanoid fraction for the opacity can be also consistent with the Galactic one. Early or late multi-wavelength observations are crucial for revealing the central engine of short gamma-ray bursts and the r-process nucleosynthesis.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-02-21T19:00:02.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gravitational wave event gw170817",
      "energy source",
      "short gamma-ray bursts",
      "binary neutron star",
      "broader parameter spaces"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}