The Role of Fission in Neutron Star Mergers and Its Impact on the r-Process Peaks
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[The Role of Fission in Neutron Star Mergers and its Impact on the r-Process Peaks]
Authors
Eichler, Marius
Arcones, Almudena
Kelic, Alexandra
Korobkin, Oleg
Langanke, Karlheinz
Marketin, Tomislav
Martinez-Pinedo, Gabriel
Panov, Igor
Rauscher, Thomas
Rosswog, Stephan
Author (Corporation)
Publication date
15.07.2015
Typ of student thesis
Course of study
Collections
Type
01A - Journal article
Editors
Editor (Corporation)
Supervisor
Parent work
The Astrophysical Journal
Special issue
DOI of the original publication
Link
Series
Series number
Volume
808
Issue / Number
1
Pages / Duration
13-43
Patent number
Publisher / Publishing institution
The American Astronomical Society
Place of publication / Event location
Washington
Edition
Version
Programming language
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Practice partner / Client
Abstract
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 β-decays compete and an (n,γ)-(γ,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 β-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.
Keywords
nucleosynthesis, stars:neutron, r-process
Subject (DDC)
Event
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ISBN
ISSN
1538-4357
0004-637X
0004-637X
Language
English
Created during FHNW affiliation
Yes
Strategic action fields FHNW
Publication status
Published
Review
Peer review of the complete publication
Open access category
License
Citation
Eichler, M., Arcones, A., Kelic, A., Korobkin, O., Langanke, K., Marketin, T., Martinez-Pinedo, G., Panov, I., Rauscher, T., Rosswog, S., Winteler, C., Zinner, N., & 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), 13–43. https://doi.org/10.1088/0004-637X/808/1/30