Comparison of the Core-collapse Evolution of Two Nearly Equal-mass Progenitors

Abstract

We compare the core-collapse evolution of a pair of 15.8 M ☉ stars with significantly different internal structures, a consequence of the bimodal variability exhibited by massive stars during their late evolutionary stages. The 15.78 and 15.79 M ☉ progenitors have core masses (masses interior to an entropy of 4 k B baryon−1) of 1.47 and 1.78 M ☉ and compactness parameters ξ 1.75 of 0.302 and 0.604, respectively. The core-collapse simulations are carried out in 2D to nearly 3 s postbounce and show substantial differences in the times of shock revival and explosion energies. The 15.78 M ☉ model begins exploding promptly at 120 ms postbounce when a strong density decrement at the Si–Si/O shell interface, not present in the 15.79 M ☉ progenitor, encounters the stalled shock. The 15.79 M ☉ model takes 100 ms longer to explode but ultimately produces a more powerful explosion. Both the larger mass accretion rate and the more massive core of the 15.79 M ☉ model during the first 0.8 s postbounce time result in larger ν e / ν ¯ e luminosities and RMS energies along with a flatter and higher-density heating region. The more-energetic explosion of the 15.79 M ☉ model resulted in the ejection of twice as much 56Ni. Most of the ejecta in both models are moderately proton rich, though counterintuitively the highest electron fraction (Y e = 0.61) ejecta in either model are in the less-energetic 15.78 M ☉ model, while the lowest electron fraction (Y e = 0.45) ejecta in either model are in the 15.79 M ☉ model.

Physical mechanism of core-collapse supernovae that neutrinos drive

“…The two simulations cited here (see also Refs. 128 and 138 ) demonstrated clearly that this long computations are indeed needed to predict unambiguously some observable quantities that are critically important to judge if the numerical model is truly successful. So far, the results look very encouraging.…”

“…After 3D-simulation uproar, one of the important progresses is the long-term multi-D simulations. 7 , 38 , 138 ) By the long-term simulation, we mean here the one well beyond a second postbounce, i.e. , up to the time when the explosion energy is finally determined.…”

Observing Supernova Neutrino Light Curves with Super-Kamiokande. IV. Development of SPECIAL BLEND: A New Public Analysis Code for Supernova Neutrinos

“…The bounce shock eventually stalls due to energy loss, but the energetic neutrinos emitted from the PNS energize the shock to revive, leading to the explosion. Many theoretical works have been dedicated to uncovering the mechanism (Vartanyan et al 2019;Harada et al 2020;Iwakami et al 2020;Matsumoto et al 2020;Bollig et al 2021;Burrows & Vartanyan 2021;Kuroda 2021;Bruenn et al 2023). However, we have not yet reached a conclusion due to an incomplete theoretical model and a lack of observational data.…”

Neutrino-driven Outflows and the Elemental Abundance Patterns of Very Metal-poor Stars

“…Current simulations show that neutrinos drive most of the matter to protonrich conditions. However, some bubbles or pockets of material expand quickly and stay slightly neutron-rich (for example, O'Connor 2015; Harris et al 2017;Müller et al 2017;Eichler et al 2018;Wanajo et al 2018;Bollig et al 2021;Burrows & Vartanyan 2021;Bruenn et al 2023;Navó et al 2023).…”