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

• Published in: The Astrophysical journal Vol. 872; no. 2; pp. 155 - 171
• Main Authors: Fujisawa, Kotaro, Okawa, Hirotada, Yamamoto, Yu, Yamada, Shoichi
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 20.02.2019; IOP Publishing
• Subjects: Accretion; Angular momentum; Astrophysics; Centrifugal force; Computational fluid dynamics; Deposition; Explosions; Fluid flow; Hydrodynamic equations; Hydrodynamics; Lorentz force; Luminosity; Magnetic fields; Magnetism; magnetohydrodynamics (MHD); methods: numerical; Neutrinos; Numerical methods; Shock waves; stars: magnetic field; stars: rotation; Stellar rotation; Supernova; supernovae: general; Two dimensional flow
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/aaffdd

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 × 1012-3.0 × 1012 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.