The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability

By N. Nishimura, H. Sawai, T. Takiwaki, S. Yamada, Friedrich-Karl Thielemann. 2016

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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 (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 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 ( ) 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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/cbac4c42ed2966eb384e54d84f5f3222bca27b9a