The r-process - The theoretical/astrophysical side

Shinya Wanajo, Hans-Thomas Janka, Bernhard Müller

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All the current r-process scenarios relevant to core-collapse supernovae are facing severe difficulties. In particular, recent core-collapse simulations with neutrino transport show no sign of a neutron-rich wind from the proto-neutron star. Recent one-dimensional (1D) hydrodynamical simulations of core-collapse supernovae (CCSNe) with a sophisticated treatment of neutrino transport indicate the neutrino-driven winds being proton-rich all the way until the end of their activity. New 2D explosion simulations of electron-capture supernovae (ECSNe; a subset of CCSNe) exhibit, however, convective neutron-rich lumps, which are absent in the 1D case. Our nucleosynthesis calculations indicate that these neutron-rich lumps allow for interesting production of elements between iron group and N = 50 nuclei (from Zn to Zr, with little Ga). Our models do not confirm, however, ECSNe as sources of the strong r-process (but possibly of a weak r-process up to Pd, Ag, and Cd in the neutron-rich lumps). We further discuss nucleosynthesis of the r-process in an alternative astrophysical site, "black hole winds", the neutrino-driven outflows from the accretion torus around a black hole. This condition is assumed to be realized in double neutron star mergers, neutron star - black hole mergers, or hypernovae, but we argue that conditions for strong r-processing are more likely to be realized in the merger case.

Original languageEnglish
JournalProceedings of Science
Publication statusPublished - 2010
Externally publishedYes

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