Features of the Acoustic Mechanism of Core-Collapse Supernova Explosions

We review the status of the current quest to understand the mechanism of core-collapse supernovae, if neutrino-driven. In the process, we discuss the spherical explosion paradigm and its problems, some results from our new suite of collapse calculations performed using a recently-developed 1D implicit, multi-group, Feautrier/tangent-ray, Boltzmann solver coupled to explicit predictor/corrector hydrodynamics, the basic energetics of supernova explosions, and the promise of mul...

Recent observations of supernovae, supernova remnants, and radio pulsars suggest that there are correlations between pulsar kicks and spins, infrared and gamma-ray line profiles, supernova polarizations, and ejecta debris fields. A framework is emerging in which explosion asymmetries play a central role. The new perspective meshes recent multi-dimensional theoretical investigations of the explosion mechanism with trends in $^{56}$Ni yields and explosion kinetic energies. Thes...

Assuming that the neutrino luminosity from the neutron star core is sufficiently high to drive supernova explosions by the neutrino-heating mechanism, we show that low-mode (l = 1, 2) convection can develop from random seed perturbations behind the shock. A slow onset of the explosion is crucial, requiring the core luminosity to vary slowly with time, in contrast to the burst-like exponential decay assumed in previous work. Gravitational and hydrodynamic forces by the globall...

We investigate in this paper the core-collapse supernova explosion mechanism in both one and two dimensions. We verify the usefulness of neutrino-driven overturn (``convection'') between the shock and the neutrinosphere in igniting the supernova explosion. The 2-D simulation of the core of a 15$\mdot$ star that we present here indicates that the breaking of spherical symmetry may be central to the explosion itself and that a multitude of bent and broken fingers is a common fe...

Nonspherical mass motions are a generic feature of core-collapse supernovae, and hydrodynamic instabilities play a crucial role for the explosion mechanism. First successful neutrino-driven explosions could be obtained with self-consistent, first-principle simulations in three spatial dimensions (3D). But 3D models tend to be less prone to explosion than corresponding axisymmetric (2D) ones. This has been explained by 3D turbulence leading to energy cascading from large to sm...

Fresh insights and powerful numerical tools are revitalizing the theoretical exploration of the supernova mechanism. The realization that the protoneutron star is Rayleigh-Taylor unstable at various times and radii and, hence, that a multi-dimensional perspective is required is one agent of this revolution. However, a new physical understanding of the nature of explosions (even spherical explosions) that are driven by neutrino heating and that escape from deep within a gravit...

We show that neutrino-driven pulsar kicks can increase the energy of the supernova shock. The observed large velocities of pulsars are believed to originate in the supernova explosion, either from asymmetries in the ejecta or from an anisotropic emission of neutrinos (or other light particles) from the cooling neutron star. In this paper we assume the velocities are caused by anisotropic neutrino emission and study the effects of these neutrino-driven kicks on the supernova e...

Two-dimensional simulations of strongly anisotropic supernova explosions of a nonrotating 15 solar mass blue supergiant progenitor are presented, which follow the hydrodynamic evolution from times shortly after shock formation until hours later. It is shown that explosions which around the time of shock revival are dominated by low-order unstable modes (i.e. by a superposition of the l=2 and l=1 modes, in which the former is strongest), are consistent with all major observati...

Advances in our understanding and the modeling of stellar core-collapse and supernova explosions over the past 15 years are reviewed, concentrating on the evolution of hydrodynamical simulations, the description of weak interactions and nuclear equation of state effects, and new insights into the nucleosynthesis occurring in the early phases of the explosion, in particular the neutrino-p process. The latter is enabled by the proton-richness of the early ejecta, which was disc...

We show by two-dimensional and first three-dimensional simulations of neutrino-driven supernova explosions that low (l=1,2) modes can dominate the flow pattern in the convective postshock region on timescales of hundreds of milliseconds after core bounce. This can lead to large global anisotropy of the supernova explosion and pulsar kicks in excess of 500 km/s.