TY - JOUR

T1 - Effects of Rotation and Magnetic Field on the Revival of a Stalled Shock in Supernova Explosions

AU - Fujisawa, Kotaro

AU - Okawa, Hirotada

AU - Yamamoto, Yu

AU - Yamada, Shoichi

N1 - Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved..

PY - 2019

Y1 - 2019

N2 - We investigate axisymmetric steady solutions of (magneto)hydrodynamics equations that approximately describe accretion flows through a standing shock wave onto a protoneutron star and discuss the effects of rotation and magnetic field on the revival of the stalled shock wave in supernova explosions. We develop a new powerful numerical method to calculate the two-dimensional steady accretion flows self-consistently. We first confirm the results of preceding papers that there is a critical luminosity of irradiating neutrinos, above which there exists no steady solution in spherical models. If a collapsing star is rotating and/or has a magnetic field, the accretion flows are no longer spherical owing to the centrifugal force and/or Lorentz force, and the critical luminosity is modified. In fact, we find that the critical luminosity is reduced by about 50%-70% for very rapid rotations; the rotation frequencies are 0.2-0.45 s -1 at the radius of r = 1000 km (equivalent to spin periods ∼0.5-0.22 ms at r = 10 km) and about 20%-50% for strong toroidal magnetic fields (the strengths of which are 1.0 × 10 12 -3.0 × 10 12 G at r = 1000 km), depending on the mass accretion rate. These results may also be interpreted as the existence of a critical specific angular momentum or critical magnetic field, above which there exists no steady solution and the standing shock wave will be revived for a given combination of mass accretion rate and neutrino luminosity.

AB - We investigate axisymmetric steady solutions of (magneto)hydrodynamics equations that approximately describe accretion flows through a standing shock wave onto a protoneutron star and discuss the effects of rotation and magnetic field on the revival of the stalled shock wave in supernova explosions. We develop a new powerful numerical method to calculate the two-dimensional steady accretion flows self-consistently. We first confirm the results of preceding papers that there is a critical luminosity of irradiating neutrinos, above which there exists no steady solution in spherical models. If a collapsing star is rotating and/or has a magnetic field, the accretion flows are no longer spherical owing to the centrifugal force and/or Lorentz force, and the critical luminosity is modified. In fact, we find that the critical luminosity is reduced by about 50%-70% for very rapid rotations; the rotation frequencies are 0.2-0.45 s -1 at the radius of r = 1000 km (equivalent to spin periods ∼0.5-0.22 ms at r = 10 km) and about 20%-50% for strong toroidal magnetic fields (the strengths of which are 1.0 × 10 12 -3.0 × 10 12 G at r = 1000 km), depending on the mass accretion rate. These results may also be interpreted as the existence of a critical specific angular momentum or critical magnetic field, above which there exists no steady solution and the standing shock wave will be revived for a given combination of mass accretion rate and neutrino luminosity.

KW - magnetohydrodynamics (MHD)

KW - methods: numerical

KW - shock waves

KW - stars: magnetic field

KW - stars: rotation

KW - supernovae: general

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U2 - 10.3847/1538-4357/aaffdd

DO - 10.3847/1538-4357/aaffdd

M3 - Article

AN - SCOPUS:85063421921

SN - 0004-637X

VL - 872

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 155

ER -