Electron-capture and Low-mass Iron-core-collapse Supernovae: New Neutrino-radiation-hydrodynamics Simulations

Abstract

We present new 1D(spherical)and 2D(axisymmetric)simulations of electron-capture(EC)and low-mass iron-core-collapse supernovae(SN). We consider six progenitor models: the ECSN progenitor from Nomoto; two ECSN-likelow-mass low-metallicity iron-core progenitors from A. Heger(2016, private communication); and the 9, 10, and11M(zero-age main-sequence)progenitors from Sukhbold et al. We confirm that the ECSN and ESCN-likeprogenitors explode easily even in 1D with explosion energies of up to a 0.15 Bethes(º1 B 10 erg51),andareaviable mechanism for the production of very-low-mass neutron stars. However, the 9, 10, and 11Mprogenitors donot explode in 1D and are not even necessarily easier to explode than higher-mass progenitor stars in 2D. We studythe effect of perturbations and of changes to the microphysics and wefind that relatively small changes can result inqualitatively different outcomes, even in 1D, for models sufficiently close to the explosion threshold. Finally, werevisit the impact of convection below the protoneutron star(PNS)surface. We analyze 1D and 2D evolutions ofPNSs subject to the same boundary conditions. Wefind that the impact of PNS convection has been underestimatedin previous studies and could result in an increase of the neutrino luminosity by up to factors of two.