THE EVOLUTION AND IMPACTS OF MAGNETOROTATIONAL INSTABILITY IN MAGNETIZED CORE-COLLAPSE SUPERNOVAE

ABSTRACT We carried out two-dimensional axisymmetric MHD simulations of core-collapse supernovae for rapidly rotating magnetized progenitors. By changing both the strength of the magnetic field and the spatial resolution, the evolution of the magnetorotational instability (MRI) and its impacts upon...

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Bibliographic Details
Published in:The Astrophysical journal 2016-02, Vol.817 (2), p.153
Main Authors: Sawai, Hidetomo, Yamada, Shoichi
Format: Article
Language:English
Subjects:
ANGULAR MOMENTUM TRANSFER
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
AXIAL SYMMETRY
Collimation
COMPUTERIZED SIMULATION
Dynamics
ELECTRON CAPTURE
Explosions
Heating
HEATING RATE
instabilities
INSTABILITY
JETS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
magnetohydrodynamics (MHD)
methods: numerical
Neutrinos
NEUTRON STARS
SPATIAL RESOLUTION
stars: magnetars
SUPERNOVAE
supernovae: general
TWO-DIMENSIONAL SYSTEMS
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Summary:ABSTRACT We carried out two-dimensional axisymmetric MHD simulations of core-collapse supernovae for rapidly rotating magnetized progenitors. By changing both the strength of the magnetic field and the spatial resolution, the evolution of the magnetorotational instability (MRI) and its impacts upon the dynamics are investigated. We found that the MRI greatly amplifies the seed magnetic fields in the regime where the buoyant mode, not the Alfvén mode, plays a primary role in the exponential growth phase. The MRI indeed has a powerful impact on the supernova dynamics. It makes the shock expansion faster and the explosion more energetic, with some models being accompanied by the collimated jet formations. These effects, however, are not made by the magnetic pressure except for the collimated jet formations. The angular momentum transfer induced by the MRI causes the expansion of the heating region, by which the accreting matter gain additional time to be heated by neutrinos. The MRI also drifts low-Yp matter from deep inside of the core to the heating region, which makes the net neutrino heating rate larger by the reduction of the cooling due to the electron capture. These two effects enhance the efficiency of the neutrino heating, which is found to be the key to boosting the explosion. Indeed, we found that our models explode far more weakly when the net neutrino heating is switched off. The contribution of the neutrino heating to the explosion energy could reach 60% even in the case of strongest magnetic field in the current simulations.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/817/2/153