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The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability
Abstract
We investigated r-process nucleosynthesis in magneto-rotational supernovae, based on a new explosion mechanism induced by the magneto-rotational instability (MRI). A series of axisymmetric magneto-hydrodynamical simulations with detailed microphysics including neutrino heating is performed, numerically resolving the MRI. Neutrino-heating dominated explosions, enhanced by magnetic fields, showed mildly neutron-rich ejecta producing nuclei up to $A\sim 130$ (i.e., the weak r-process), while explosion models with stronger magnetic fields reproduce a solar-like r-process pattern. More commonly seen abundance patterns in our models are in between the weak and regular r-process, producing lighter and intermediate-mass nuclei. These intermediate r-processes exhibit a variety of abundance distributions, compatible with several abundance patterns in r-process-enhanced metal-poor stars. The amount of Eu ejecta $\sim {10}^{-5}\,{M}_{\odot }$ in magnetically driven jets agrees with predicted values in the chemical evolution of early galaxies. In contrast, neutrino-heating dominated explosions have a significant amount of Fe (${}^{56}{\rm{Ni}}$) and Zn, comparable to regular supernovae and hypernovae, respectively. These results indicate magneto-rotational supernovae can produce a wide range of heavy nuclei from iron-group to r-process elements, depending on the explosion dynamics.
Acceptance Date | Feb 2, 2017 |
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Publication Date | Feb 16, 2017 |
Journal | Astrophysical Journal Letters |
Print ISSN | 2041-8205 |
Publisher | American Astronomical Society |
DOI | https://doi.org/10.3847/2041-8213/aa5dee |
Keywords | gamma-ray burst: general, magnetohydrodynamics (MHD), neutrinos, nuclear reactions, nucleosynthesis, abundances, stars: neutron, supernovae: general |
Publisher URL | https://iopscience.iop.org/article/10.3847/2041-8213/aa5dee |
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