We present a new mechanism for core-collapse supernova explosions that
relies upon acoustic power generated in the inner core as the
driver. If, and in the circumstances in which, the neutrino mechanism does
not obtain, this acoustic mechanism would come into its own. In our
simulations, a strong advective-acoustic oscillation a la Foglizzo with a
period of ~25-30 milliseconds (ms) arises ~200 ms after bounce. Its growth
saturates due to the generation of secondary shocks, and kinks in the
resulting shock structure funnel and regulate subsequent accretion onto the
inner core. However, this instability is not the primary agent of
explosion. Rather, it is the acoustic power generated in the inner
turbulent region and most importantly by the excitation and sonic damping
of core g-mode oscillations. An l=1 mode with a period of ~3 ms grows to
be prominent around ~500 ms after bounce. The accreting protoneutron star
is a self-excited oscillator. The associated acoustic power seen in our
11-solar-mass simulation is sufficient to drive the explosion. The angular
distribution of the emitted sound is fundamentally aspherical, and the
resulting blast is almost unipolar. The sound pulses radiated from the core
steepen into shock waves that merge as they propagate into the outer mantle
and deposit their energy and momentum with high efficiency. The core
oscillation acts like a transducer to convert accretion energy into
sound. An advantage of the acoustic mechanism is that acoustic power does
not abate until accretion subsides, so that it is available as long as it
may be needed to explode the star, unless a black hole is formed. The
consequences of this new mechanism for the explosion morphology, the
r-process, pulsar kicks, and the systematics with progentior mass and
rotation will be explored.
To begin viewing slides, click on the first slide below. (Or, view as pdf.)