r-process nucleosynthesis from matter ejected in binary neutron star mergers

  • When binary systems of neutron stars merge, a very small fraction of their rest mass is ejected, either dynamically or secularly. This material is neutron-rich and its nucleosynthesis provides the astrophysical site for the production of heavy elements in the Universe, together with a kilonova signal confirming neutron-star mergers as the origin of short gamma-ray bursts. We perform full general-relativistic simulations of binary neutron-star mergers employing three different nuclear-physics equations of state (EOSs), considering both equal- and unequal-mass configurations, and adopting a leakage scheme to account for neutrino radiative losses. Using a combination of techniques, we carry out an extensive and systematic study of the hydrodynamical, thermodynamical, and geometrical properties of the matter ejected dynamically, employing the WinNet nuclear-reaction network to recover the relative abundances of heavy elements produced by each configurations. Among the results obtained, three are particularly important. First, we find that, within the sample considered here, both the properties of the dynamical ejecta and the nucleosynthesis yields are robust against variations of the EOS and masses. Second, using a conservative but robust criterion for unbound matter, we find that the amount of ejected mass is ≲10−3 M⊙, hence at least one order of magnitude smaller than what normally assumed in modelling kilonova signals. Finally, using a simplified and gray-opacity model we assess the observability of the infrared kilonova emission finding, that for all binaries the luminosity peaks around ∼1=2 day in the H-band, reaching a maximum magnitude of −13, and decreasing rapidly after one day.

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Author:Luke BovardGND, Dirk MartinGND, Federico Maria GuercilenaORCiDGND, Almudena Arcones SegoviaORCiDGND, Luciano RezzollaORCiDGND, Oleg KorobkinORCiD
Parent Title (English):Physical Review. D
Place of publication:Woodbury, NY
Document Type:Article
Date of Publication (online):2017/12/05
Date of first Publication:2017/12/05
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/12/08
Tag:General relativity; General relativity equations & solutions; Nucleosynthesis in explosive environments; Transient & explosive astronomical phenomena
Issue:12, art. 124005
Article Number:124005
Page Number:25
First Page:1
Last Page:25
This research is supported in part by the ERC Synergy Grant “BlackHoleCam: Imaging the Event Horizon of Black Holes” (Grant No. 610058), the ERC starting grant “EUROPIUM” (Grant No. 677912), by “NewCompStar”, COST Action MP1304, by the LOEWE-Program in the Helmholtz International Center (HIC) for FAIR, by the European Union’s Horizon 2020 Research and Innovation Programme (Grant No. 671698) (call FETHPC-1-2014, project ExaHyPE), by the Helmholtz-University Young Investigator Grant No. VH-NG-825, and by the BMBF under Grant No. 05P15RDFN1.
Institutes:Physik / Physik
Wissenschaftliche Zentren und koordinierte Programme / Frankfurt Institute for Advanced Studies (FIAS)
Forschungscluster / ELEMENTS
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoDeutsches Urheberrecht