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J. M. Blondin (North Carolina State University), A. Mezzacappa (Oak Ridge National Labs)
We use 2D numerical simulations to study the linear response of the stalled accretion shock during the first few hundred milliseconds after core bounce in core-collapse supernovae. We use these simulations to measure the growth rate and frequency of the Spherical Accretion Shock Instability, or SASI. These simulations demonstrate that the l=1 mode (in spherical harmonics) is the most unstable, with a characteristic growth time of order 50 msec. Further, these simulations provide evidence that the SASI is due to the growth of a normal acoustic mode trapped inside the accretion shock. The dynamical response of the shock to interior pressure perturbations leads to a rapid amplification of the trapped acoustic wave. The result is that core-collapse supernova may "ring" with a frequency of order 15 Hz, with rapid growth of the acoustic oscillations leading to nonlinear changes in the accretion shock within a few hundred milliseconds.
This work was performed under the auspices of the TeraScale Supernova Initiative, funded by SciDAC grants from the DOE Office of Science High-Energy, Nuclear, and Advanced Scientific Computing Research Programs.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.