2019/05/14 by Benjamin Wehmeyer, B. Wehmeyer, C. Frohlich +6
Physics and Astronomy · #Astronomy #Astrophysics #Galaxy #Gamma-ray bursts and supernovae #Laser-Plasma Interactions and Diagnostics #Metallicity #Neutron star #Nucleosynthesis #Physics #Pulsars and Gravitational Waves Research #Stars #Supernova #astro-ph.GA #r-process
paper · pdf · doi:10.1093/mnras/stz1310
published as 2019 Monthly Notices of the Royal Astronomical Society, Volume 487, Issue 2, p.1745-1753
openalex publication_date 2019/05/14 · openalex created_date 2019/05/29 · arxiv created 2019/08/15 · arxiv updated 2019/08/16 · openalex updated_date 2026/08/06
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.