{
  "id": "1810.04664",
  "version": "v1",
  "published": "2018-10-10T17:57:52.000Z",
  "updated": "2018-10-10T17:57:52.000Z",
  "title": "A long-lived neutron star merger remnant in GW170817: constraints and clues from X-ray observations",
  "authors": [
    "L. Piro",
    "E. Troja",
    "B. Zhang",
    "G. Ryan",
    "H. van Eerten",
    "R. Ricci",
    "M. H. Wieringa",
    "A. Tiengo",
    "N. R. Butler",
    "S. B. Cenko",
    "O. D. Fox",
    "H. G. Kandrika",
    "G. Novara",
    "A. Rossi",
    "T. Sakamoto"
  ],
  "comment": "10 pages, 7 figs, MNRAS subm",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Multi-messenger observations of GW170817 have not conclusively established whether the merger remnant is a black hole (BH) or a neutron star (NS). We show that a long-lived magnetized NS with a poloidal field $B\\approx 10^{12}$G is fully consistent with the electromagnetic dataset, when spin down losses are dominated by gravitational wave (GW) emission. The required ellipticity $\\epsilon\\gtrsim 10^{-5}$ can result from a toroidal magnetic field component much stronger than the poloidal component, a configuration expected from a NS newly formed from a merger. Abrupt magnetic dissipation of the toroidal component can lead to the appearance of X-ray flares, analogous to the one observed in gamma-ray burst (GRB) afterglows. In the X-ray afterglow of GW170817 we identify a low-significance temporal feature at 155 d, consistent with a sudden reactivation of the central NS. Energy injection from the NS spin down into the relativistic shock is negligible, and the underlying continuum is fully accounted for by a structured jet seen off-axis. Whereas radio and optical observations probe the interaction of this jet with the surrounding medium, observations at X-ray wavelengths, performed with adequate sampling, open a privileged window on to the merger remnant.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-10-10T17:57:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "long-lived neutron star merger remnant",
      "x-ray observations",
      "constraints",
      "toroidal magnetic field component",
      "low-significance temporal feature"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}