EXPLOSIVE NUCLEOSYNTHESIS IN THE NEUTRINO-DRIVEN ASPHERICAL SUPERNOVA EXPLOSION OF A NON-ROTATING 15M_☉STAR WITH SOLAR METALLICITY

Abstract

We investigate explosive nucleosynthesis in a non-rotating 15M ⊙ star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with the mass number ≤ 70 employing a large nuclear reaction network. Aspherical abundance distributions, which are observed in nearby core-collapse SN remnants, are obtained for the non-rotating spherically-symmetric progenitor, due to the growth of low-mode SASI. Abundance pattern of the supernova ejecta is similar to that of the solar system for models whose masses ranges (0.4 − 0.5)M ⊙ of the ejecta from the inner region (≤ 10, 000 km) of the precollapse core. For the models, the explosion energies and the 56 Ni masses are ≃ 10 51 erg and (0.05 − 0.06)M ⊙ , respectively; their estimated baryonic masses of the neutron star are comparable to the ones observed in neutron-star binaries. These findings may have little uncertainty because most of the ejecta is composed by matter that is heated via the shock wave and has relatively definite abundances. The abundance ratios for Ne, Mg, Si and Fe observed in Cygnus loop are well reproduced with the SN ejecta from an inner region of the 15M ⊙ progenitor.

Nucleosynthesis in neutrino-driven, aspherical Population III supernovae

“…Here 52 erg s −1 , respectively. We note that abundances of SN ejecta are shown to depend not directly on L ν and T ν , but on the explosion energy and the mass of the proto-neutron star, as shown in Fujimoto et al (2011). It should be emphasized that magnitude and asymmetry of the explosion energy are evaluated for the simulations.…”

“…For 2D hydrodynamic simulations of neutrino-driven SNe, we employ a numerical code, which is based on the ZEUS-2D code, as in Ohnishi et al (2006) and Fujimoto et al (2011). We assume that the fluid is axisymmetric and that neutrinos are isotropically emitted from the neutrino spheres with given luminosities and with the Fermi-Dirac distribution of given temperatures.…”

“…We assume that the fluid is axisymmetric and that neutrinos are isotropically emitted from the neutrino spheres with given luminosities and with the Fermi-Dirac distribution of given temperatures. Initial conditions for the hydrodynamic simulations are similarly arranged as in Fujimoto et al (2011). The central region inside 50 km in radius is excised to follow a long-term postbounce evolution.…”

“…We consider models with neutrino temperatures, T νe , Tν e , and T νx as 4, 5, and 10 MeV, respectively, as in Ohnishi et al (2006) and Fujimoto et al (2011). We take the input neutrino luminosities from L νe ,min to L νe ,max for a given M ms , because the revival of the stalled bounce shock occurs only for models with L νe L νe ,min and also because for models with L νe > L νe ,max , the star explodes too early for the SASI to grow.…”

“…Next we calculate abundances and masses of the SN ejecta in a same manner as in Fujimoto et al (2011). Ejecta that is located on the central part of the star ( 10, 000 km) before the core collapse has high enough maximum temperatures for elements heavier than C to burn explosively.…”