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Title: The role of fission on neutron star mergers and its impact on the r-process peaks

Abstract

The comparison between observational abundance features and those obtained from nucleosynthesis predictions of stellar evolution and/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. Here we test the abundance features of r-process nucleosynthesis calculations using four different fission fragment distribution models. Furthermore, we explore the origin of a shift in the third r-process peak position in comparison with the solar r-process abundances which has been noticed in a number of merger nucleosynthesis predictions. We show that this 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.

Authors:
;  [1]; ; ;  [2];  [3];  [4]; ;  [5];  [6];  [7];  [8];  [9];  [8];  [10];  [11]
  1. Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel (Switzerland)
  2. Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 2, D-64289 Darmstadt (Germany)
  3. (Germany)
  4. GSI Helmholtzzentrum fr Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt (Germany)
  5. The Oskar Klein Centre, Department of Astronomy, AlbaNova, Stockholm University, SE-10691 Stockholm (Sweden)
  6. Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia)
  7. SSC RF ITEP of NRC “Kurchatov Institute”, Bolshaya Cheremushkinskaya 25, 117218 Moscow (Russian Federation)
  8. (Switzerland)
  9. Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)
  10. Institut Energie am Bau, Fachhochschule Nordwestschweiz, St. Jakobs-Strasse 84, 4132 Muttenz (Switzerland)
  11. Department of Physics and Astronomy, Aarhus University, Ny Munkegade, bygn. 1520, DK-8000 Aarhus C (Denmark)
Publication Date:
OSTI Identifier:
22609082
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1743; Journal Issue: 1; Conference: CETUP 2015: Workshop on dark matter, neutrino physics and astrophysics, Deadwood, SD (United States), 15 Jun - 17 Jul 2015, PPC 2015: 9. international conference on interconnections between particle physics and cosmology, Deadwood, SD (United States), 15 Jun - 17 Jul 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BETA DECAY; CAPTURE; DISTRIBUTION; EQUILIBRIUM; EXPLOSIONS; FISSION; FISSION FRAGMENTS; FORECASTING; HALF-LIFE; NEUTRON REACTIONS; NEUTRON STARS; NUCLEAR PHYSICS; NUCLEI; NUCLEOSYNTHESIS; R PROCESS; SIMULATION

Citation Formats

Eichler, M., E-mail: marius.eichler@unibas.ch, Thielemann, F.-K., Arcones, A., Langanke, K., Martinez-Pinedo, G., GSI Helmholtzzentrum fr Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt, Kelic, A., Korobkin, O., Rosswog, S., Marketin, T., Panov, I., Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel, Rauscher, T., Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel, Winteler, C., and Zinner, N. T. The role of fission on neutron star mergers and its impact on the r-process peaks. United States: N. p., 2016. Web. doi:10.1063/1.4953296.
Eichler, M., E-mail: marius.eichler@unibas.ch, Thielemann, F.-K., Arcones, A., Langanke, K., Martinez-Pinedo, G., GSI Helmholtzzentrum fr Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt, Kelic, A., Korobkin, O., Rosswog, S., Marketin, T., Panov, I., Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel, Rauscher, T., Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel, Winteler, C., & Zinner, N. T. The role of fission on neutron star mergers and its impact on the r-process peaks. United States. doi:10.1063/1.4953296.
Eichler, M., E-mail: marius.eichler@unibas.ch, Thielemann, F.-K., Arcones, A., Langanke, K., Martinez-Pinedo, G., GSI Helmholtzzentrum fr Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt, Kelic, A., Korobkin, O., Rosswog, S., Marketin, T., Panov, I., Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel, Rauscher, T., Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel, Winteler, C., and Zinner, N. T. Tue . "The role of fission on neutron star mergers and its impact on the r-process peaks". United States. doi:10.1063/1.4953296.
@article{osti_22609082,
title = {The role of fission on neutron star mergers and its impact on the r-process peaks},
author = {Eichler, M., E-mail: marius.eichler@unibas.ch and Thielemann, F.-K. and Arcones, A. and Langanke, K. and Martinez-Pinedo, G. and GSI Helmholtzzentrum fr Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt and Kelic, A. and Korobkin, O. and Rosswog, S. and Marketin, T. and Panov, I. and Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel and Rauscher, T. and Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4055 Basel and Winteler, C. and Zinner, N. T.},
abstractNote = {The comparison between observational abundance features and those obtained from nucleosynthesis predictions of stellar evolution and/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. Here we test the abundance features of r-process nucleosynthesis calculations using four different fission fragment distribution models. Furthermore, we explore the origin of a shift in the third r-process peak position in comparison with the solar r-process abundances which has been noticed in a number of merger nucleosynthesis predictions. We show that this 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.},
doi = {10.1063/1.4953296},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1743,
place = {United States},
year = {Tue Jun 21 00:00:00 EDT 2016},
month = {Tue Jun 21 00:00:00 EDT 2016}
}