The Development of Explosions in Axisymmetric Ab Initio Core-Collapse Supernova Simulations of 12-25 $M_\odot$ Stars

We present four ab initio axisymmetric core-collapse supernova simulations initiated from 12, 15, 20, and 25 M-circle dot zero-age main sequence progenitors. All of the simulations yield explosions and have. been evolved for at least 1.2 s after core bounce and 1 s after material first becomes unbound. These simulations were computed with our CHIMERA code employing RbR spectral neutrino transport, special and general relativistic transport effects, and state-of-the-art neutrino interactions. Continuing the evolution beyond 1 s after core bounce allows the explosions to develop more fully and the processes involved in powering the explosions to become more clearly evident. We compute explosion energy estimates, including the negative gravitational binding energy of the stellar envelope outside the expanding shock, of 0.34, 0.88, 0.38, and 0.70 Bethe (B 10(51) erg) and increasing at 0.03, 0.15, 0.19, and 0.52 B s(-1), respectively, for the 12, 15, 20, and 25 M-circle dot models at the endpoint of this report. We examine the growth of the explosion energy in our models through detailed analyses of the energy sources and flows. We discuss how the explosion energies may be subject to stochastic variations as exemplfied by the effect of the explosion geometry of the 20 M-circle dot model in reducing its explosion energy. We compute the proto-neutron star masses and kick velocities. We compare our results for the explosion energies and ejected Ni-56 masses against some observational standards despite the large error bars in both models and observations.