Numerical simulations of driven supersonic relativistic MHD turbulence

Jonathan Zrake, Andrew MacFadyen

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Models for GRB outflows invoke turbulence in relativistically hot magnetized fluids. In order to investigate these conditions we have performed high-resolution three-dimensional numerical simulations of relativistic magneto-hydrodynamical (RMHD) turbulence. We find that magnetic energy is amplified to several percent of the total energy density by turbulent twisting and folding of magnetic field lines. Values of εB ≳ 0.01 are thus naturally expected. We study the dependence of saturated magnetic field energy fraction as a function of Mach number and relativistic temperature. We then present power spectra of the turbulent kinetic and magnetic energies. We also present solenoidal (curl-like) and dilatational (divergence-like) power spectra of kinetic energy. We propose that relativistic effects introduce novel couplings between these spectral components. The case we explore in most detail is for equal amounts of thermal and rest mass energy, corresponding to conditions after collisions of shells with relative Lorentz factors of several. These conditions are relevant in models for internal shocks, for the late afterglow phase, for cocoon material along the edge of a relativistic jet as it propagates through a star, as well neutron stars merging with each other and with black hole companions. We find that relativistic turbulence decays extremely quickly, on a sound crossing time of an eddy. Models invoking sustained relativistic turbulence to explain variability in GRB prompt emission are thus strongly disfavored unless a persistant driving of the turbulence is maintained for the duration of the prompt emission.

    Original languageEnglish (US)
    Title of host publicationGamma Ray Bursts 2010, GRB 2010
    Pages102-105
    Number of pages4
    DOIs
    StatePublished - 2011
    EventGamma Ray Bursts 2010, GRB 2010 - Annapolis, MD, United States
    Duration: Nov 1 2010Nov 4 2010

    Publication series

    NameAIP Conference Proceedings
    Volume1358
    ISSN (Print)0094-243X
    ISSN (Electronic)1551-7616

    Other

    OtherGamma Ray Bursts 2010, GRB 2010
    CountryUnited States
    CityAnnapolis, MD
    Period11/1/1011/4/10

    Keywords

    • Bursts
    • Gamma-rays
    • Hydrodynamics
    • Methods
    • Numerical
    • Relativistic MHD
    • Turbulence

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

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