The γ-rays that accompanied GW170817 and the observational signature of a magnetic jet breaking out of NS merger ejecta

O. Bromberg, A. Tchekhovskoy, O. Gottlieb, E. Nakar, T. Piran

Research output: Contribution to journalArticlepeer-review

Abstract

We present the first relativistic magnetohydrodynamics numerical simulation of a magnetic jet that propagates through and emerges from the dynamical ejecta of a binary neutron star merger. Generated by the magnetized rotation of the merger remnant, the jet propagates through the ejecta and produces an energetic cocoon that expands at mildly relativistic velocities and breaks out of the ejecta. We show that if the ejecta has a low-mass (∼10-7 M) high-velocity (v ∼0.85c) tail, the cocoon shock breakout will generate γ-ray emission that is comparable to the observed short GRB170817A that accompanied the recent gravitational wave event GW170817. Thus, we propose that this gamma-ray burst (GRB), which is quite different from all other short GRBs observed before, was produced by a different mechanism. We expect, however, that such events are numerous and many will be detected in coming LIGO-Virgo runs.

Original languageEnglish
Pages (from-to)2971-2977
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume475
Issue number3
DOIs
StatePublished - 1 Apr 2018

Keywords

  • gamma-ray burst: individual:170817A
  • relativistic processes
  • stars: jets
  • stars: magnetars
  • stars: magnetic field
  • stars: neutron

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