Abstract
We present an overview of four ab initio axisymmetric core-collapse
supernova simulations employing detailed spectral neutrino transport
computed with our CHIMERA code and initiated from Woosley & Heger (2007)
progenitors of mass 12, 15, 20, and 25 M_sun. All four models exhibit
shock revival over ~ 200 ms (leading to the possibility of explosion),
driven by neutrino energy deposition. Hydrodynamic instabilities that impart
substantial asymmetries to the shock aid these revivals, with convection appearing
first in the 12 solar mass model and the standing accretion shock instability (SASI)
appearing first in the 25 solar mass model. Three of the models have developed
pronounced prolate morphologies (the 20 solar mass model has remained approximately
spherical). By 500 ms after bounce the mean shock radii in all four models exceed
3,000 km and the diagnostic explosion energies are 0.33, 0.66, 0.65, and 0.70 Bethe
(B=10^{51} ergs) for the 12, 15, 20, and 25 solar mass models, respectively, and are
increasing. The three least massive of our models are already sufficiently energetic
to completely unbind the envelopes of their progenitors (i.e., to explode), as
evidenced by our best estimate of their explosion energies, which first become
positive at 320, 380, and 440 ms after bounce. By 850 ms the 12 solar mass diagnostic
explosion energy has saturated at 0.38 B, and our estimate for the final kinetic
energy of the ejecta is ~ 0.3 B, which is comparable to observations for
lower-mass progenitors.
