{
  "id": "1411.2015",
  "version": "v1",
  "published": "2014-11-07T20:02:21.000Z",
  "updated": "2014-11-07T20:02:21.000Z",
  "title": "Short gamma-ray bursts in the \"time-reversal\" scenario",
  "authors": [
    "Riccardo Ciolfi",
    "Daniel M. Siegel"
  ],
  "comment": "5 pages, 2 figures",
  "categories": [
    "astro-ph.HE",
    "astro-ph.SR"
  ],
  "abstract": "Short gamma-ray bursts (SGRBs) are among the most luminous explosions in the Universe and their origin still remains uncertain. Observational evidence favors the association with binary neutron star or neutron star-black hole (NS-BH) binary mergers. Leading models relate SGRBs to a relativistic jet launched by the BH-torus system resulting from the merger. However, recent observations have revealed a large fraction of SGRB events accompanied by X-ray afterglows with durations $\\sim\\!10^2-10^5~\\mathrm{s}$, suggesting continuous energy injection form a long-lived central engine, which is incompatible with the short ($\\lesssim\\!1~\\mathrm{s}$) accretion timescale of a BH-torus system. The formation of a supramassive NS, resisting the collapse on much longer spin-down timescales, can explain these afterglow durations, but leaves serious doubts on whether a relativistic jet can be launched at merger. Here we present a novel scenario accommodating both aspects, where the SGRB is produced after the collapse of a supramassive NS. Early differential rotation and subsequent spin-down emission generate an optically thick environment around the NS consisting of a photon-pair nebula and an outer shell of baryon-loaded ejecta. While the jet easily drills through this environment, spin-down radiation diffuses outwards on much longer timescales and accumulates a delay that allows the SGRB to be observed before (part of) the long-lasting X-ray signal. By analyzing diffusion timescales for a wide range of physical parameters, we find delays that can generally reach $\\sim\\!10^5~\\mathrm{s}$, compatible with observations. The success of this fundamental test makes this \"time-reversal\" scenario an attractive alternative to current SGRB models.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-11-07T20:02:21.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "short gamma-ray bursts",
      "time-reversal",
      "bh-torus system",
      "subsequent spin-down emission generate",
      "relativistic jet"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/2041-8205/798/2/L36",
      "journal": "The Astrophysical Journal",
      "year": 2015,
      "month": "Jan",
      "volume": 798,
      "number": 2
    },
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1326622,
      "adsabs": "2015ApJ...798L..36C"
    }
  }
}