The Development of Explosions in Axisymmetric Ab Initio Core-Collapse Supernova Simulations of 12–25 Stars

Abstract

We present four ab initio axisymmetric core-collapse supernova simulations initiated from 12, 15, 20, and 25 M  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  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  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.

Crucial Physical Dependencies of the Core-Collapse Supernova Mechanism

“…Since the neutrino power deposition goes approximately as the product of this depth and the luminosities, high-compactness progenitors have an advantage. Therefore, it is feasible that more massive models might be more explosive, and this trend has been seen by other modelers (Summa et al , 2018Bruenn et al 2016). In fact, in the Summa et al and Bruenn et al papers for the Woosley and Heger (2007) models, the postbounce explosion times increase in the sequence 20, 25, 15, and 12 M , which is clearly not monotonic with compactness.…”

“…To the point, Skinner et al (2016) have shown that the ray-by-ray anomalies in the angular distribution of the radiation field and corresponding neutrino heating rates can reinforce the axial sloshing motions in 2D and push the shock into explosion. 1 Bruenn et al (2013Bruenn et al ( , 2016 find explosions in 2D (axially symmetry) for all the progenitors they studied (the 12-, 15-, 20-, and 25-M models of Woosley and Heger 2007), but the models all explode at about the same post-bounce time (∼100 milliseconds) and the shock radii never decrease in value. When performed in 3D for the 15-M model of Woosley and Heger (2007), Lentz et al (2015) obtain a weaker explosion delayed in its onset by an extra ∼100 milliseconds.…”

“…In fact, the numerical algorithms, resolutions, and input physics all differ, and even when the physics is deemed similar, the implementations and approximations surely differ. The ORNL group (Bruenn et al 2013(Bruenn et al , 2016, with their CHIMERA code, uses multi-group flux-limited diffusion (MGFLD) neutrino transport (Bruenn 1985), the VH-1 Newtonian hydrodynamics package, a monopole correction for general relativity (GR) (Marek et al 2006), but multiple one-dimensional solves for multi-dimensional transport using the so-called "ray-by-ray+" approach (Buras et al 2003;Burrows et al 1995). Such a dimensional reduction for the transport, particularly manifest in 2D, ignores lateral, non-radial radiative transport, which has been shown to be of quantitative (Ott et al 2008;Brandt et al 2011;Burrows 2013;Dolence et al 2015;Sumiyoshi et al 2015) and qualitative (Skinner et al 2016) importance.…”

General-Relativistic Three-Dimensional Multi-Group Neutrino Radiation-Hydrodynamics Simulations of Core-Collapse Supernovae

“…Detailed spherically symmetric one-dimensional (1D) simulations do not explode (Liebendörfer et al 2001), except when particular low-mass progenitor models are used (e.g., Fischer et al 2010;Hüdepohl et al 2010). Multiple simulations including energydependent (multi-group) neutrino transport and imposing axial symmetry (2D) do exhibit explosions (Müller et al 2012b(Müller et al , 2012aBruenn et al 2013Bruenn et al , 2016, although some do not . Interestingly, the first simulations including ray-by-ray neutrino transport 11 without symmetries imposed three-dimensionally on the hydrodynamics did not find explosions in models that exploded when axisymmetry was assumed (Hanke et al 2013).…”

The two promising scenarios to explode core collapse supernovae

“…The delayed neutrino mechanism (e.g., Bruenn et al 2016;Janka et al 2016;Müller 2016;Burrows et al 2017), although the most popular in the literature, encounters problems (e.g., Papish et al 2015;Kushnir 2015b). An alternative mechanism to account for all CCSNe is the jet feedback mechanism (JFM; for a review see .…”