Article révisé par les pairs
| Résumé : | The rapid neutron-capture process, or r-process, is known to beof fundamental importance for explaining the origin of approximately half of theA > 60 stable nuclei observed in nature. Recently, special attention has been paidto neutron star (NS) mergers following the confirmation by hydrodynamic simulationsthat a non-negligible amount of matter can be ejected and by nucleosynthesiscalculations combined with the predicted astrophysical event rate that such a sitecan account for the majority of r-material in our Galaxy. We show here that thecombined contribution of both the dynamical (prompt) ejecta, expelled during binaryNS or NS-black hole (BH) mergers, and the neutrino as well as viscously drivenoutflows generated during the post-merger remnant evolution of relic BH-torus systemscan lead to the production of r-process elements from mass number A>90up to actinides. The corresponding abundance distribution is found to reproducethe solar distribution extremely well. It can also account for the elemental distributionsobserved in low-metallicity stars. However, major uncertainties still affectour understanding of the composition of the ejected matter. These concern (i) theβ-interactions of electron (anti)neutrinos with free neutrons and protons, as well astheir inverse reactions, which may affect the neutron-richness of the matter at theearly phase of the ejection, and (ii) the nuclear physics of exotic neutron-rich nuclei,including nuclear structure as well as nuclear interaction properties, which impactthe calculated abundance distribution. Both aspects are discussed in the light ofrecent hydrodynamical simulations of NS mergers and microscopic calculations ofnuclear decay and reaction probabilities. |
