{
  "id": "2111.04621",
  "version": "v1",
  "published": "2021-11-08T16:48:57.000Z",
  "updated": "2021-11-08T16:48:57.000Z",
  "title": "General-relativistic neutrino-radiation magnetohydrodynamics simulation of black hole-neutron star mergers for seconds",
  "authors": [
    "Kota Hayashi",
    "Sho Fujibayashi",
    "Kenta Kiuchi",
    "Koutarou Kyutoku",
    "Yuichiro Sekiguchi",
    "Masaru Shibata"
  ],
  "categories": [
    "astro-ph.HE",
    "gr-qc"
  ],
  "abstract": "Seconds-long numerical-relativity simulations for black hole-neutron star mergers are performed for the first time to obtain a self-consistent picture of the merger and post-merger evolution processes. To investigate the case that tidal disruption takes place, we choose the initial mass of the black hole to be $5.4M_\\odot$ or $8.1M_\\odot$ with the dimensionless spin of 0.75. The neutron-star mass is fixed to be $1.35M_\\odot$. We find that after the tidal disruption, dynamical mass ejection takes place spending $\\lesssim 10\\,{\\rm ms}$ together with the formation of a massive accretion disk. Subsequently, the magnetic field in the disk is amplified by the magnetic winding and magnetorotational instability, establishing a turbulent state and inducing the angular momentum transport. The post-merger mass ejection by the magnetically-induced viscous effect sets in at $\\sim 300$-$500\\,{\\rm ms}$ after the tidal disruption, at which the neutrino luminosity drops below $\\sim 10^{51.5}\\,{\\rm erg/s}$, and continues for several hundreds ms. A magnetosphere near the rotational axis of the black hole is developed after the matter and magnetic flux fall into the black hole from the accretion disk, and high-intensity Poynting flux generation sets in at a few hundreds ms after the tidal disruption. The intensity of the Poynting flux becomes low after the significant post-merger mass ejection, because the opening angle of the magnetosphere increases. The lifetime for the stage with the strong Poynting flux is $1$-$2\\,{\\rm s}$, which agrees with the typical duration of short-hard gamma-ray bursts.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-11-08T16:48:57.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "black hole-neutron star mergers",
      "general-relativistic neutrino-radiation magnetohydrodynamics simulation",
      "tidal disruption",
      "poynting flux generation sets",
      "post-merger mass ejection"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}