Dependence of weak interaction rates on the nuclear composition during stellar core collapse

Abstract

We investigate the influences of the nuclear composition on the weak interaction rates of heavy nuclei during the core collapse of massive stars. The nuclear abundances in nuclear statistical equilibrium (NSE) are calculated by some equation of state (EOS) models including in-medium effects on nuclear masses. We systematically examine the sensitivities of electron capture and neutrino-nucleus scattering on heavy nuclei to the nuclear shell effects and the single nucleus approximation. We find that the washout of shell effects at high temperatures brings significant change to weak rates by smoothing the nuclear abundance distribution: the electron capture rate decreases by $\sim$20$\%$ in the early phase and increases by $\sim$40$\%$ in the late phase at most, while the cross section for neutrino-nucleus scattering is reduced by $\sim$15$\%$. This is because the open-shell nuclei become abundant instead of those with closed neutron shells as the shell effects disappear. We also find that the single-nucleus description based on the average values leads to underestimations of weak rates. Electron captures and neutrino coherent scattering on heavy nuclei are reduced by $\sim$80$\%$ in the early phase and by $\sim$5$\%$ in the late phase, respectively. These results indicate that NSE like EOS accounting for shell washout is indispensable for the reliable estimation of weak interaction rates in simulations of core-collapse supernovae.

28 pages 14 figures, accepted for publication in Phys. Rev. C

References in corpus (4)

• Light nuclei quasiparticle energy shift in hot and dense nuclear matter
• Interplay of Neutrino Opacities in Core-collapse Supernova Simulations
• A comparative study of statistical models for nuclear equation of state of stellar matter
• In-medium nuclear cluster energies within the Extended Thomas-Fermi approach

Cited by in corpus (6)

• Fast-pairwise collective neutrino oscillations associated with asymmetric neutrino emissions in core-collapse supernova
• A new equation of state for core-collapse supernovae based on realistic nuclear forces and including a full nuclear ensemble
• Comparing treatments of weak reactions with nuclei in simulations of core-collapse supernovae
• Self consistent calculation of the nuclear composition in hot and dense stellar matter
• The sensitivity of presupernova neutrinos to stellar evolution models
• Equation of state and neutrino transfer in supernovae and neutron stars