A narrow short-duration GRB JET from a wide central engine

Paul C. Duffell, Eliot Quataert, Andrew I. Macfadyen

    Research output: Contribution to journalArticle

    Abstract

    We use two-dimensional relativistic hydrodynamic numerical calculations to show that highly collimated relativistic jets can be produced in neutron star merger models of short-duration gamma-ray bursts (GRBs) without the need for a highly directed engine or a large net magnetic flux. Even a hydrodynamic engine generating a very wide sustained outflow on small scales can, in principle, produce a highly collimated relativistic jet, facilitated by a dense surrounding medium that provides a cocoon surrounding the jet core. An oblate geometry to the surrounding gas significantly enhances the collimation process. Previous numerical simulations have shown that the merger of two neutron stars produces an oblate, expanding cloud of dynamical ejecta. We show that this gas can efficiently collimate the central engine power much like the surrounding star does in long-duration GRB models. For typical short-duration GRB central engine parameters, we find jets with opening angles of an order of 10° in which a large fraction of the total outflow power of the central engine resides in highly relativistic material. These results predict large differences in the opening angles of outflows from binary neutron star mergers versus neutron star-black hole mergers.

    Original languageEnglish (US)
    Article number64
    JournalAstrophysical Journal
    Volume813
    Issue number1
    DOIs
    StatePublished - Nov 1 2015

    Fingerprint

    gamma ray bursts
    engines
    engine
    merger
    neutron stars
    outflow
    hydrodynamics
    cocoon
    binary stars
    collimation
    ejecta
    gases
    gas
    magnetic flux
    geometry
    stars
    simulation

    Keywords

    • gamma-ray burst: general
    • hydrodynamics
    • ISM: jets and outflows
    • relativistic processes
    • shock waves

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    A narrow short-duration GRB JET from a wide central engine. / Duffell, Paul C.; Quataert, Eliot; Macfadyen, Andrew I.

    In: Astrophysical Journal, Vol. 813, No. 1, 64, 01.11.2015.

    Research output: Contribution to journalArticle

    Duffell, Paul C. ; Quataert, Eliot ; Macfadyen, Andrew I. / A narrow short-duration GRB JET from a wide central engine. In: Astrophysical Journal. 2015 ; Vol. 813, No. 1.
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