The role of neutron star mergers and core collapse supernovae in r process nucleosynthesis
Abstract
Recent IR/optical/UV observations and Gamma-ray burst rate determinations at high redshift have led to significant progress in establishing the cosmic evolution of the star formation rate density (SFRD). The SFRD is then used to predict the ionization history of the Universe, and the evolution of the cosmic chemical abundances, supernova rates, etc, as a function of the redshift z. These predictions are done in the framework of the hierarchical model for structure formation. In this context, we focus here our attention on the origin and evolution of a typical r process element: Europium, in two possible sites: core collapse supernovae (SNII) or Neutron Star Mergers (NSM). In the first scenario, there is only one parameter, the yield of Eu produced in these SNII. In the second one, there are three physical parameters, Eu yield, binary star fraction and time delay before the merger. The comparison of our results with available observations of Eu in stars at various metallicities strongly favors the NSM site for the r process. In addition, it allows to put a constraint on the time delay for mergers, which is typically 0.1-0.2 Gyr, and to make an independent prediction for the expected rate of mergers in the horizon of the adv Virgo/Ligo detectors, which we find typically to be of the order of 3 to 10 events per year for NS/NS and NS/BH mergers respectively.
- Publication:
-
SF2A-2014: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics
- Pub Date:
- December 2014
- Bibcode:
- 2014sf2a.conf...89D
- Keywords:
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- R process nucleosynthesis;
- neutron star mergers;
- supernovae;
- cosmic chemical evolution.