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 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.
Additional Information
© 2017 American Physical Society. Received 6 August 2016; published 24 February 2017. S.F. and H.N. are supported by the Japan Society for the Promotion of Science Postdoctoral Fellowships for Research Abroad. We are grateful to the Goethe Graduate Academy for proofreading. H.N. was partially supported at Caltech through NSF Award No. TCAN AST-1333520. Some numerical calculations were carried out on the PC cluster at the Center for Computational Astrophysics, National Astronomical Observatory of Japan. This work is supported in part by the usage of supercomputer systems through the Large Scale Simulation Program (Grants No. 15/16/-08 and No. 16/17-11) of the High Energy Accelerator Research Organization (KEK) and Post-K Projects (Grants No. hp 150225, No. hp160071, and No. hp160211) at K-computer, RIKEN AICS, as well as the resources provided by the RCNP at Osaka University, the YITP at Kyoto University, the University of Tokyo, and the JLDG. This work was supported by Grants-in-Aid for the Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (Grants No. 24103006, No. 24244036, No. 16H03986, No. 15K05093, and No. 24105008).Attached Files
Published - PhysRevC.95.025809.pdf
Submitted - 1701.08414.pdf
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Additional details
- Eprint ID
- 74538
- Resolver ID
- CaltechAUTHORS:20170227-085133716
- Japan Society for the Promotion of Science (JSPS)
- AST-1333520
- NSF
- 15/16/-08
- High Energy Accelerator Research Organization (KEK)
- 16/17-11
- High Energy Accelerator Research Organization (KEK)
- hp150225
- High Energy Accelerator Research Organization (KEK)
- hp160071
- High Energy Accelerator Research Organization (KEK)
- hp160211
- High Energy Accelerator Research Organization (KEK)
- 24103006
- Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 24244036
- Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 16H03986
- Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 15K05093
- Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 24105008
- Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- Created
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2017-02-27Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field