title: A large-scale dynamo and magnetoturbulence in rapidly rotating core-collapse supernovae.
abstract: Magnetohydrodynamic turbulence is important in many high-energy astrophysical systems, where instabilities can amplify the local magnetic field over very short timescales. Specifically, the magnetorotational instability and dynamo action have been suggested as a mechanism for the growth of magnetar-strength magnetic fields (of 10(15) gauss and above) and for powering the explosion of a rotating massive star. Such stars are candidate progenitors of type Ic-bl hypernovae, which make up all supernovae that are connected to long γ-ray bursts. The magnetorotational instability has been studied with local high-resolution shearing-box simulations in three dimensions, and with global two-dimensional simulations, but it is not known whether turbulence driven by this instability can result in the creation of a large-scale, ordered and dynamically relevant field. Here we report results from global, three-dimensional, general-relativistic magnetohydrodynamic turbulence simulations. We show that hydromagnetic 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 γ-ray bursts, and provide a viable mechanism for the formation of magnetars. Moreover, our findings suggest that rapidly rotating massive stars might lie behind potentially magnetar-powered superluminous supernovae.
authors.affiliation: TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, California 91125, USA.|Department of Astronomy, 501 Campbell Hall #3411, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Philipp
authors.initials: P
authors.lastname: Mösta
authors.affiliation: TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Christian D
authors.initials: CD
authors.lastname: Ott
authors.affiliation: TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: David
authors.initials: D
authors.lastname: Radice
authors.affiliation: TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Luke F
authors.initials: LF
authors.lastname: Roberts
authors.affiliation: Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada.|Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.|Center for Computation &Technology, Louisiana State University, Baton Rouge, Louisiana, 70803, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Schnetter
authors.affiliation: Max Planck Institute for Gravitational Physics, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Haas