Search

We present a suite of seven 3D supernova simulations of non-rotating low-mass progenitors using multigroup neutrino transport. Our simulations cover single star progenitors with zero-age main-sequence masses between |$9.6$| and |$12.5 \, \mathrm{M}_\odot$| and (ultra)stripped-envelope progenitors with initial helium core masses between |$2.8$| and |$3.5 \, \mathrm{M}_\odot$|⁠. We find explosion energies between |$0.1$| and |$0.4\, \mathrm{Bethe}$|⁠, which are still rising by the end of the simulations. Although less energetic than typical events, our models are compatible with observations of less energetic explosions of low-mass progenitors. In six of our models, the mass outflow rate already exceeds the accretion rate on to the proto-neutron star, and the mass and angular momentum of the compact remnant have closely approached their final value, barring the possibility of later fallback. While the proto-neutron star is still accelerated by the gravitational tug of the asymmetric ejecta, the acceleration can be extrapolated to obtain estimates for the final kick velocity. We obtain gravitational neutron star masses between |$1.22$| and |$1.44 \, \mathrm{M}_\odot$|⁠, kick velocities between |$11$| and |$695\, \mathrm{km}\, \mathrm{s}^{-1}$|⁠, and spin periods from |$20\, \mathrm{ms}$| to |$2.7\, \mathrm{s}$|⁠, which suggest that typical neutron star birth properties can be naturally obtained in the neutrino-driven paradigm. We find a loose correlation between the explosion energy and the kick velocity. There is no indication of spin–kick alignment, but a correlation between the kick velocity and the neutron star angular momentum, which needs to be investigated further as a potential point of tension between models and observations. [ABSTRACT FROM AUTHOR]

The recent discoveries of many double neutron star systems and their detection as LIGO-Virgo merger events call for a detailed understanding of their origin. Explosions of ultrastripped stars in binary systems have been shown to play a key role in this context and have also generated interest as a potential explanation for rapidly evolving hydrogen-free transients. Here, we present the first attempt to model such explosions based on binary evolution calculations that follow the mass transfer to the companion to obtain a consistent core-envelope structure as needed for reliable predictions of the supernova transient. We simulate the explosion in 2D and 3D, and confirm the modest explosion energies $${\sim } 10^{50}\, \mathrm{erg}$$ and small kick velocities reported earlier in 2D models based on bare carbon–oxygen cores. The spin-up of the neutron star by asymmetric accretion is small in 3D with no indication of spin-kick alignment. Simulations up to shock breakout show the mixing of sizeable amounts of iron group material into the helium envelope. In view of recent ideas for a mixing-length treatment (MLT) of Rayleigh–Taylor instabilities in supernovae, we perform a detailed analysis of the mixing, which reveals evidence for buoyancy-drag balance, but otherwise does not support the MLT approximation. The mixing may have implications for the spectroscopic signatures of ultrastripped supernovae that need to be investigated in the future. Our stellar evolution calculation also predicts presupernova mass-loss due to an off-centre silicon deflagration flash, which suggests that supernovae from extremely stripped cores may show signs of interactions with circumstellar material. [ABSTRACT FROM AUTHOR]