On the astrophysical robustness of the neutron star merger r process
2012 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 426, no 3, 1940-1949 p.Article in journal (Refereed) Published
In this study we explore nucleosynthesis in the dynamic ejecta of compact binary mergers. We are particularly interested in the question how sensitive the resulting abundance patterns are to the parameters of the merging system. Therefore, we systematically investigate combinations of neutron star masses in the range from 1.0 to 2.0 M? and, for completeness, we compare the results with those from two simulations of a neutron star black hole merger. The ejecta masses vary by a factor of 5 for the studied systems, but all amounts are (within the uncertainties of the merger rates) compatible with being a major source of the cosmic r-process. The ejecta undergo robust r-process nucleosynthesis which produces all the elements from the second to the third peak in close-to-solar ratios. Most strikingly, this r-process is extremely robust, and all 23 investigated binary systems yield practically identical abundance patterns. This is mainly the result of the ejecta being extremely neutron rich (Ye similar to 0.04) and the r-process path meandering along the neutron drip line so that the abundances are determined entirely by nuclear rather than astrophysical properties. While further questions related to galactic chemical evolution need to be explored in future studies, we consider this robustness together with the ease with which both the second and third peak are reproduced as strong indications that compact binary mergers are prime candidates for the sources of the observed unique heavy r-process component.
Place, publisher, year, edition, pages
2012. Vol. 426, no 3, 1940-1949 p.
equation of state, gravitation, hydrodynamics, neutrinos, nuclear reactions, nucleosynthesis, abundances
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-83029DOI: 10.1111/j.1365-2966.2012.21859.xISI: 000310063900020OAI: oai:DiVA.org:su-83029DiVA: diva2:574414