{
  "id": "2412.05760",
  "version": "v1",
  "published": "2024-12-07T23:03:45.000Z",
  "updated": "2024-12-07T23:03:45.000Z",
  "title": "Black hole pulsars and monster shocks as outcomes of black hole-neutron star mergers",
  "authors": [
    "Yoonsoo Kim",
    "Elias R. Most",
    "Andrei M. Beloborodov",
    "Bart Ripperda"
  ],
  "comment": "18 pages, 12 figures, submitted to ApJL",
  "categories": [
    "astro-ph.HE",
    "gr-qc"
  ],
  "abstract": "The merger of a black hole (BH) and a neutron star (NS) in most cases is expected to leave no material around the remnant BH; therefore, such events are often considered as sources of gravitational waves without electromagnetic counterparts. However, a bright counterpart can emerge if the NS is strongly magnetized, as its external magnetosphere can experience radiative shocks and magnetic reconnection during/after the merger. We use magnetohydrodynamic simulations in the dynamical spacetime of a merging BH-NS binary to investigate its magnetospheric dynamics. We find that the magnetosphere develops compressive waves that steepen into shocks. After swallowing the NS, the BH acquires a magnetosphere that quickly evolves into a split monopole configuration and then undergoes an exponential decay (balding), enabled by magnetic reconnection and also assisted by the ring-down of the remnant BH. This spinning BH drags the split monopole into rotation, forming a transient pulsar-like state. It emits a striped wind if the swallowed magnetic dipole moment is inclined to the spin axis. We predict two types of transients from this scenario: (1) a fast radio burst emitted by the shocks as they expand to large radii and (2) an X/gamma-ray burst emitted by the $e^\\pm$ outflow heated by magnetic dissipation.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-12-07T23:03:45.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "black hole-neutron star mergers",
      "black hole pulsars",
      "monster shocks",
      "remnant bh",
      "magnetic reconnection"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 18,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}