Neutrino-Induced Nucleosynthesis in Helium Shells of Early Core-Collapse Supernovae
1 School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
2 Monash Center for Astrophysics, School of Physics and Astronomy, Monash University, Victoria 3800, Australia
3 Department of Physics, University of California Berkeley, Berkeley, California 94620, USA
4 Lawrence Berkeley National Laboratory, Berkeley, California 94620, USA
5 Center for Nuclear Astrophysics, INPAC, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, Peoples Republic of China
a e-mail: email@example.com
Published online: 12 February 2016
We summarize our studies on neutrino-driven nucleosynthesis in He shells of early core-collapse supernovae with metallicities of Z ≲ 10−3 Z⊙. We find that for progenitors of ∼ 11–15 M⊙, the neutrons released by 4He(e, e+n)3H in He shells can be captured to produce nuclei with mass numbers up to A ∼ 200. This mechanism is sensitive to neutrino emission spectra and flavor oscillations. In addition, we find two new primary mechanisms for neutrino-induced production of 9Be in He shells. The first mechanism produces 9Be via 7Li(n,γ)8Li(n,γ)9Li(e− e)9Be and relies on a low explosion energy for its survival. The second mechanism operates in progenitors of ∼ 8 M⊙, where 9Be can be produced directly via 7Li(3H, n0)9Be during the rapid expansion of the shocked Heshell material. The light nuclei 7Li and 3H involved in these mechanisms are produced by neutrino interactions with 4He. We discuss the implications of neutrino-induced nucleosynthesis in He shells for interpreting the elemental abundances in metal-poor stars.
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