THE EVOLUTION AND IMPACTS OF MAGNETOROTATIONAL INSTABILITY IN MAGNETIZED CORECOLLAPSE SUPERNOVAE
Abstract
We carried out twodimensional axisymmetric MHD simulations of corecollapse 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 lowY{sub p} 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 tomore »
 Authors:
 Research Organization for Information Science and Technology, Kobe, Hyogo 6500047 (Japan)
 Waseda University, Shinjuku, Tokyo 1698555 (Japan)
 Publication Date:
 OSTI Identifier:
 22521616
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Astrophysical Journal; Journal Volume: 817; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANGULAR MOMENTUM TRANSFER; AXIAL SYMMETRY; COMPUTERIZED SIMULATION; ELECTRON CAPTURE; HEATING RATE; INSTABILITY; JETS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; NEUTRON STARS; SPATIAL RESOLUTION; SUPERNOVAE; TWODIMENSIONAL SYSTEMS
Citation Formats
Sawai, Hidetomo, and Yamada, Shoichi, Email: hsawai@rist.or.jp. THE EVOLUTION AND IMPACTS OF MAGNETOROTATIONAL INSTABILITY IN MAGNETIZED CORECOLLAPSE SUPERNOVAE. United States: N. p., 2016.
Web. doi:10.3847/0004637X/817/2/153.
Sawai, Hidetomo, & Yamada, Shoichi, Email: hsawai@rist.or.jp. THE EVOLUTION AND IMPACTS OF MAGNETOROTATIONAL INSTABILITY IN MAGNETIZED CORECOLLAPSE SUPERNOVAE. United States. doi:10.3847/0004637X/817/2/153.
Sawai, Hidetomo, and Yamada, Shoichi, Email: hsawai@rist.or.jp. 2016.
"THE EVOLUTION AND IMPACTS OF MAGNETOROTATIONAL INSTABILITY IN MAGNETIZED CORECOLLAPSE SUPERNOVAE". United States.
doi:10.3847/0004637X/817/2/153.
@article{osti_22521616,
title = {THE EVOLUTION AND IMPACTS OF MAGNETOROTATIONAL INSTABILITY IN MAGNETIZED CORECOLLAPSE SUPERNOVAE},
author = {Sawai, Hidetomo and Yamada, Shoichi, Email: hsawai@rist.or.jp},
abstractNote = {We carried out twodimensional axisymmetric MHD simulations of corecollapse 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 lowY{sub p} 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.},
doi = {10.3847/0004637X/817/2/153},
journal = {Astrophysical Journal},
number = 2,
volume = 817,
place = {United States},
year = 2016,
month = 2
}

We investigated the impact of magnetorotational instability (MRI) on the dynamics of weakly magnetized, rapidly rotating corecollapse supernovae by conducting highresolution axisymmetric MHD simulations with simplified neutrino transfer. We found that an initially submagnetarclass magnetic field is drastically amplified by MRI and substantially affects the dynamics thereafter. Although the magnetic pressure is not strong enough to eject matter, the amplified magnetic field efficiently transfers angular momentum from small to large radii and from higher to lower latitudes, which causes the expansion of the heating region due to the extra centrifugal force. This then enhances the efficiency of neutrino heating andmore »

LOCAL SIMULATIONS OF THE MAGNETOROTATIONAL INSTABILITY IN CORECOLLAPSE SUPERNOVAE
Bearing in mind the application of corecollapse supernovae, we study the nonlinear properties of the magnetorotational instability (MRI) by means of threedimensional simulations in the framework of a local shearing box approximation. By systematically changing the shear rates that symbolize the degree of differential rotation in nascent protoneutron stars (PNSs), we derive a scaling relation between the turbulent stress sustained by the MRI and the shearvorticity ratio. Our parametric survey shows a powerlaw scaling between the turbulent stress (((w {sub tot}))) and the shearvorticity ratio (g{sub q} ) as ((w {sub tot})){proportional_to}g {sup {delta}} {sub q} with an index ofmore » 
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MAGNETOROTATIONAL CORECOLLAPSE SUPERNOVAE IN THREE DIMENSIONS
We present results of new threedimensional (3D) generalrelativistic magnetohydrodynamic simulations of rapidly rotating strongly magnetized core collapse. These simulations are the first of their kind and include a microphysical finitetemperature equation of state and a leakage scheme that captures the overall energetics and lepton number exchange due to postbounce neutrino emission. Our results show that the 3D dynamics of magnetorotational corecollapse supernovae are fundamentally different from what was anticipated on the basis of previous simulations in axisymmetry (2D). A strong bipolar jet that develops in a simulation constrained to 2D is crippled by a spiral instability and fizzles in fullmore » 
EFFECTS OF RESISTIVITY ON MAGNETIZED CORECOLLAPSE SUPERNOVAE
We studied the role of turbulent resistivity in the corecollapse of a strongly magnetized massive star, carrying out twodimensional resistiveMHD simulations. Three cases with different initial strengths of magnetic field and rotation are investigated: (1) a strongly magnetized rotating core, (2) a moderately magnetized rotating core, and (3) a very strongly magnetized nonrotating core. In each case, one idealMHD model and two resistiveMHD models are computed. As a result of these computations, each model shows an eruption of matter assisted by magnetic acceleration (and also by centrifugal acceleration in the rotating cases). We found that resistivity attenuates the explosion inmore »