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

Shun Furusawa, Hiroki Nagakura, Kohsuke Sumiyoshi, Chinami Kato, Shoichi Yamada

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    18 Citations (Scopus)

    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 the shell effect at high temperatures brings significant change to weak rates by smoothing the nuclear abundance distribution: the electron capture rate decreases by ∼20% in the early phase and increases by ∼40% in the late phase at most, while the cross section for neutrino-nucleus scattering is reduced by ∼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 ∼80% in the early phase and by ∼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.

    Original languageEnglish
    Article number025809
    JournalPhysical Review C
    Volume95
    Issue number2
    DOIs
    Publication statusPublished - 2017 Feb 24

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics

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