Deleptonization and Nonaxisymmetric Instabilities in Core-Collapse Supernovae
Abstract
The timescale of deleptonization by neutrino loss and associated contraction of a proto-neutron star is short compared to the time it takes to propagate a shock through the helium core of a massive star, and so the deleptonization phase does not occur in the vacuum of space, but within the supernova ambiance, whether or not there has been a successful explosion. Dynamical nonaxisymmetric instabilities (NAXI) are predicted for sufficiently strongly differentially rotating proto-neutron stars. Some modes are unstable for small values of the ratio of rotational kinetic energy to binding energy, T/W>~0.01. The NAXI are likely to drive magnetoacoustic waves into the surrounding time-dependent density structure. These waves represent a mechanism of the dissipation of the free energy of differential rotation of the proto-neutron star, and the outward deposition of this energy may play a role in the supernova explosion process. We estimate the power produced by this process and the associated timescale and discuss the possible systematics of the deleptonization phase in this context. A likely possibility is that the proto-neutron star will spin down through these effects before deleptonization and produce substantial but not excessive energy input.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2007
- DOI:
- 10.1086/509111
- arXiv:
- arXiv:astro-ph/0609717
- Bibcode:
- 2007ApJ...654..429W
- Keywords:
-
- Hydrodynamics;
- Instabilities;
- Stars: Magnetic Fields;
- Stars: Neutron;
- Stars: Rotation;
- Stars: Supernovae: General;
- Astrophysics
- E-Print:
- 15 pages, 1 figure, accepted for publication in the Astrophysical Journal