@article{wehmeyer_froehlich_cote_pignatari_thielemann_2019, title={Using failed supernovae to constrain the Galactic r-process element production}, volume={487}, ISSN={["1365-2966"]}, url={https://doi.org/10.1093/mnras/stz1310}, DOI={10.1093/mnras/stz1310}, abstractNote={ABSTRACT
               Rapid neutron capture process (r-process) elements have been detected in a large fraction of metal-poor halo stars, with abundances relative to iron (Fe) that vary by over two orders of magnitude. This scatter is reduced to less than a factor of 3 in younger Galactic disc stars. The large scatter of r-process elements in the early Galaxy suggests that the r-process is made by rare events, like compact binary mergers and rare sub-classes of supernovae. Although being rare, neutron star mergers alone have difficulties to explain the observed enhancement of r-process elements in the lowest metallicity stars compared to Fe. The supernovae producing the two neutron stars already provide a substantial Fe abundance where the r-process ejecta from the merger would be injected. In this work we investigate another complementary scenario, where the r-process occurs in neutron star-black hole mergers in addition to neutron star mergers. Neutron star-black hole mergers would eject similar amounts of r-process matter as neutron star mergers, but only the neutron star progenitor would have produced Fe. Furthermore, a reduced efficiency of Fe production from single stars significantly alters the age–metallicity relation, which shifts the onset of r-process production to lower metallicities. We use the high-resolution [(20 pc)3/cell] inhomogeneous chemical evolution tool ‘ICE’ to study the outcomes of these effects. In our simulations, an adequate combination of neutron star mergers and neutron star-black hole mergers qualitatively reproduces the observed r-process abundances in the Galaxy.}, number={2}, journal={MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY}, publisher={Oxford University Press (OUP)}, author={Wehmeyer, B. and Froehlich, C. and Cote, B. and Pignatari, M. and Thielemann, F. -K.}, year={2019}, month={Aug}, pages={1745–1753} }
 @article{thielemann_eichler_panov_wehmeyer_2017, title={Neutron star mergers and nucleosynthesis of heavy elements}, volume={67}, DOI={10.1146/annurev-nucl-101916-123246}, abstractNote={ The existence of neutron star mergers has been supported since the discovery of the binary pulsar and the observation of its orbital energy loss, consistent with General Relativity. They are considered nucleosynthesis sites of the rapid neutron-capture process (r-process), which is responsible for creating approximately half of all heavy elements beyond Fe and is the only source of elements beyond Pb and Bi. Detailed nucleosynthesis calculations based on the decompression of neutron star matter are consistent with solar r-process abundances of heavy nuclei. Neutron star mergers have also been identified with short-duration [Formula: see text]-ray bursts via their IR afterglow. The high neutron densities in ejected matter permit a violent r-process, leading to fission cycling of the heaviest nuclei in regions far from (nuclear) stability. Uncertainties in several nuclear properties affect the abundance distributions. The modeling of astrophysical events also depends on the hydrodynamic treatment, the occurrence of a neutrino wind after the merger and before the possible emergence of a black hole, and the properties of black hole accretion disks. We discuss the effect of nuclear and modeling uncertainties and conclude that binary compact mergers are probably a (or the) dominant site of the production of r-process nuclei in our Galaxy. }, journal={Annual review of nuclear and particle science, vol 67}, author={Thielemann, F. K. and Eichler, M. and Panov, I. V. and Wehmeyer, B.}, year={2017}, pages={253–274} }