Relativistic MHD simulations of core-collapse GRB jets: 3D instabilities and magnetic dissipation

Omer Bromberg, Alexander Tchekhovskoy

Research output: Contribution to journalArticlepeer-review

189 Scopus citations


Relativistic jets are associated with extreme astrophysical phenomena, like the core collapse of massive stars in gamma-ray bursts (GRBs) and the accretion on to supermassive black holes in active galactic nuclei. It is generally accepted that these jets are powered electromagnetically, by the magnetized rotation of a central compact object (black hole or neutron star). However, how the jets produce the observed emission and survive the propagation for many orders of magnitude in distance without being disrupted by current-driven instabilities is the subject of active debate. We carry out time-dependent 3D relativistic magnetohydrodynamic (MHD) simulations of relativistic, Poynting-flux-dominated jets. The jets are launched self-consistently by the rotation of a strongly magnetized central object. This determines the natural degree of azimuthal magnetic field winding, a crucial factor that controls jet stability. We find that the jets are susceptible to two types of instability: (i) a global, external kink mode that grows on long time-scales. It bodily twists the jet, reducing its propagation velocity. We show analytically that in flat density profiles, like the ones associated with galactic cores, the external mode grows and may stall the jet. In the steep profiles of stellar envelopes the external kink weakens as the jet propagates outward. (ii) a local, internal kink mode that grows over short time-scales and causes small-angle magnetic reconnection and conversion of about half of the jet electromagnetic energy flux into heat.We suggest that internal kink instability is the main dissipation mechanism responsible for powering GRB prompt emission.

Original languageEnglish
Pages (from-to)1739-1760
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - 2016
Externally publishedYes


FundersFunder number
Max-Planck/Princeton Center for Plasma PhysicsPF3- 140115
PICSciE-OIT High Performance Computing Center
Visualization Laboratory
National Science Foundation1523261, 1144374, 1410972
National Aeronautics and Space AdministrationNAS8-03060
Princeton University
School of Public Health, University of California Berkeley


    • Galaxies: jets
    • Gamma-ray burst: general
    • Quasars: general
    • Stars: magnetars
    • Stars: magnetic field


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