Adam Burrows, Joshua C. Dolence, Jeremiah W. Murphy
We investigate the structure of the stalled supernova shock in both 2D and 3D and explore the differences in the effects of neutrino heating and the standing accretion shock instability (SASI). Early after bounce, the amplitude of the dipolar mode of the shock is factors of $\sim2-$3 smaller in 3D than in 2D. However, later in both 3D and 2D the monopole and dipole modes start to grow until explosion. Whereas in 2D the $(l,m) = (1,0)$ mode changes sign quasi-periodically, producing the "up-and-down" motion always seen in modern 2D simulations, in 3D this almost never happens. Rather, when the dipolar mode starts to grow in 3D, it grows in magnitude and wanders stochastically in direction until settling before explosion to a particular patch of solid angle. The amplitude growth of this unidirectional dipole mode can precede that of the average shock radius. Furthermore, in 2D when neutrino heating is turned off, the amplitudes of the characteristic axisymmetric sloshing mode are a factor of $\sim3-$4 smaller than when neutrino heating is on. This suggests that it is neutrino-driven convection, not the SASI, which is responsible for the prominent dipolar mode seen in detailed 2D simulations, and that the SASI is at most a minor feature of supernova dynamics. The quasi-steady increase in the average shock radius and the (unoscillating) dipole, even hundreds of milliseconds before the explosion commences, may be distinctive and important signatures of 3D supernova behavior in the neutrino-driven context.
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http://arxiv.org/abs/1204.3088
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