The Role of Fission in Neutron Star Mergers and its Impact on the r-Process Peaks

Eichler, M. and Arcones, A. and Kelic, A. and Korobkin, O. and Langanke, K. and Marketin, T. and Martinez-Pinedo, G. and Panov, I. and Rauscher, T. and Rosswog, S. and Winteler, C. and Zinner, N.T. and Thielemann, F.-K.. (2015) The Role of Fission in Neutron Star Mergers and its Impact on the r-Process Peaks. The Astrophysical Journal, 808 (1). p. 30.

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Official URL: http://edoc.unibas.ch/41640/

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Comparing observational abundance features with nucleosynthesis predictions of stellar evolution or explosion simulations can scrutinize two aspects: (a) the conditions in the astrophysical production site and (b) the quality of the nuclear physics input utilized. We test the abundance features of r-process nucleosynthesis calculations for the dynamical ejecta of neutron star merger simulations based on three different nuclear mass models: The Finite Range Droplet Model (FRDM), the (quenched version of the) Extended Thomas Fermi Model with Strutinsky Integral (ETFSI-Q), and the Hartree-Fock-Bogoliubov (HFB) mass model. We make use of corresponding fission barrier heights and compare the impact of four different fission fragment distribution models on the final r-process abundance distribution. In particular, we explore the abundance distribution in the second r-process peak and the rare-earth sub-peak as a function of mass models and fission fragment distributions, as well as the origin of a shift in the third r-process peak position. The latter has been noticed in a number of merger nucleosynthesis predictions. We show that the shift occurs during the r-process freeze-out when neutron captures and {\beta}-decays compete and an (n,{\gamma})-({\gamma},n) equilibrium is not maintained anymore. During this phase neutrons originate mainly from fission of material above A = 240. We also investigate the role of {\beta}-decay half-lives from recent theoretical advances, which lead either to a smaller amount of fissioning nuclei during freeze-out or a faster (and thus earlier) release of fission neutrons, which can (partially) prevent this shift and has an impact on the second and rare-earth peak as well.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretische Physik Astrophysik (Thielemann)
UniBasel Contributors:Thielemann, Friedrich-Karl and Eichler, Marius and Rauscher, Thomas
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:The American Astronomical Society
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:30 Jun 2016 11:02
Deposited On:18 May 2016 14:57

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