A large scale dynamo and magnetoturbulence in rapidly rotating core-collapse supernovae

Dec 2, 2015
34 pages
Published in:
  • Nature 528 (2015) 376
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Abstract: (arXiv)
Magnetohydrodynamic (MHD) turbulence is of key importance in many high-energy astrophysical systems, where MHD instabilities can amplify local magnetic field over very short time scales. Specifically, the magnetorotational instability (MRI) and dynamo action have been suggested as a mechanism to grow magnetar-strength magnetic field (1015G\ge10^{15} G) and magnetorotationally power the explosion of a rotating massive star. Such stars are progenitor candidates for type Ic-bl hypernova explosions and make up all supernovae connected to long gamma-ray bursts (GRBs). The MRI has been studied with local high-resolution shearing box simulations in 3D or with global 2D simulations, but it is an open question whether MRI-driven turbulence can result in the creation of a large-scale ordered and dynamically relevant field. Here we report results from global 3D general-relativistic magnetohydrodynamic (GRMHD) turbulence simulations and show that MRI-driven MHD turbulence in rapidly rotating protoneutron stars produces an inverse cascade of energy. We find a large-scale ordered toroidal field that is consistent with the formation of bipolar magnetorotationally driven outflows. Our results demonstrate that rapidly rotating massive stars are plausible progenitors for both type Ic-bl supernovae and long GRBs, present a viable formation scenario for magnetars, and may account for potentially magnetar-powered superluminous supernovae.
Note:
  • Author's accepted version of Nature letter DOI:10.1038/nature15755, published online, Nature, Nov 30, 2015