New fission fragment distributions and r-process origin of the rare-earth elements.
Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A≳140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular, the fission fragment yields determine the creation of 110≲A≲170 nuclei. Here, we apply a new scission-point model, called SPY, to derive the fission fragment distribution (FFD) of all relevant neutron-rich, fissioning nuclei. The model predicts a doubly asymmetric FFD in the abundant A≃278 mass region that is responsible for the final recycling of the fissioning material. Using ejecta conditions based on relativistic NS merger calculations, we show that this specific FFD leads to a production of the A≃165 rare-earth peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r nuclei with A≳140.
Institut d'Astronomie et d'Astrophysique, CP-226, Université Libre de Bruxelles, 1050 Brussels, Belgium.
S
S
Goriely
C.E.A. Saclay, Irfu/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France.
J-L
JL
Sida
C.E.A. Saclay, Irfu/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France.
J-F
JF
Lemaître
C.E.A. Saclay, Irfu/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France.
S
S
Panebianco
CEA, DAM, DIF, F-91297 Arpajon, France.
N
N
Dubray
CEA, DAM, DIF, F-91297 Arpajon, France.
S
S
Hilaire
Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece and Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching, Germany.
A
A
Bauswein
Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching, Germany.
H-T
HT
Janka