Three-dimensional models of core-collapse supernovae from low-mass progenitors with implications for Crab

Abstract

<jats:title>ABSTRACT</jats:title> <jats:p>We present 3D full-sphere supernova simulations of non-rotating low-mass (∼9 M⊙) progenitors, covering the entire evolution from core collapse through bounce and shock revival, through shock breakout from the stellar surface, until fallback is completed several days later. We obtain low-energy explosions (∼0.5–1.0 × 1050 erg) of iron-core progenitors at the low-mass end of the core-collapse supernova (LMCCSN) domain and compare to a super-AGB (sAGB) progenitor with an oxygen–neon–magnesium core that collapses and explodes as electron-capture supernova (ECSN). The onset of the explosion in the LMCCSN models is modelled self-consistently using the vertex-prometheus code, whereas the ECSN explosion is modelled using parametric neutrino transport in the prometheus-HOTB code, choosing different explosion energies in the range of previous self-consistent models. The sAGB and LMCCSN progenitors that share structural similarities have almost spherical explosions with little metal mixing into the hydrogen envelope. A LMCCSN with less second dredge-up results in a highly asymmetric explosion. It shows efficient mixing and dramatic shock deceleration in the extended hydrogen envelope. Both properties allow fast nickel plumes to catch up with the shock, leading to extreme shock deformation and aspherical shock breakout. Fallback masses of $\mathord {\lesssim }\, 5\, \mathord {\times }\, 10^{-3}$ M⊙ have no significant effects on the neutron star (NS) masses and kicks. The anisotropic fallback carries considerable angular momentum, however, and determines the spin of the newly born NS. The LMCCSN model with less second dredge-up results in a hydrodynamic and neutrino-induced NS kick of &amp;gt;40 km s−1 and a NS spin period of ∼30 ms, both not largely different from those of the Crab pulsar at birth.</jats:p>

The explosion of 9–29M⊙stars as Type II supernovae: Results from radiative-transfer modeling at one year after explosion

“…To test the influence of mixing in the present set of simulations, we rerun models s9, s9p5, and s11 using the initial unmixed ejecta conditions from S16. In low-energy explosion models, the shock propagation may be initiated sooner after core bounce, cutting short the development of fluid instabilities that are at the origin of much of the chemical mixing (see, however, Stockinger et al 2020 occur in a general sense (i.e., be weak along all radial directions), it should be in this type of models. But weak mixing may occur along some radial direction in any SN II, so this test is useful to gauge the implications.…”

The spins of compact objects born from helium stars in binary systems

“…We find that NSs born from low-mass progenitors (Mexp 5 M ) and wide binaries (P orb 1 d) are generally slowly rotating, with initial rotation rates PNS 10 ms. The rotation periods of these NSs may instead be determined by asymmetric fallback accretion (e.g., Chan et al 2020;Stockinger et al 2020). NSs born from massive progenitors in close binaries can be rapidly rotating, with PNS ∼ 1 ms for the most massive progenitors in very tight binaries.…”

“…A major assumption of our predictions for NS rotation rates is that of AM conservation during the core-collapse explosion. Multi-dimensional simulations (Müller et al 2018;Chan et al 2020;Stockinger et al 2020;Janka et al 2021) instead show that that asymmetric explosions and fallback accretion can significantly alter the spin rate of the NS, spinning it up to spin periods as short as milliseconds. However, those simulations may also overestimate the spin-up via fallback because of numerical gridding effects or if fallback material is inefficiently accreted (Janka et al 2021).…”

Pulsational pair-instability supernovae: gravitational collapse, black-hole formation, and beyond

“…For our long-time simulations with the P code, we apply the tabulated Helmholtz EOS of Timmes & Swesty (2000), which takes into account arbitrarily degenerate and relativistic electrons and positrons, photons, and a set of 15 nuclear species (free neutrons, free protons, and 13 alpha nuclei from 4 He to 56 Ni; for details, see Stockinger et al 2020). At temperatures below 7×10 9 K, nuclear reactions are taken into account by a network solver.…”