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Title: r -process nucleosynthesis from matter ejected in binary neutron star mergers [On r -process nucleosynthesis from matter ejected in binary neutron star mergers]

Here, 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 smallermore » 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.« less
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [3] ; ORCiD logo [4]
  1. Johann Wolfgang Goethe-Univ., Frankfurt (Germany)
  2. Technische Univ. Darmstadt, Darmstadt (Germany); GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany)
  3. Johann Wolfgang Goethe-Univ., Frankfurt (Germany); Frankfurt Institute for Advanced Studies, Frankfurt (Germany)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-29073
Journal ID: ISSN 2470-0010; PRVDAQ; TRN: US1800818
Grant/Contract Number:
AC52-06NA25396; VH-NG-825
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 12; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; neutron star, mergers, r-process, kilonova
OSTI Identifier:
1415425
Alternate Identifier(s):
OSTI ID: 1411272

Bovard, Luke, Martin, Dirk, Guercilena, Federico, Arcones, Almudena, Rezzolla, Luciano, and Korobkin, Oleg. r-process nucleosynthesis from matter ejected in binary neutron star mergers [On r-process nucleosynthesis from matter ejected in binary neutron star mergers]. United States: N. p., Web. doi:10.1103/PhysRevD.96.124005.
Bovard, Luke, Martin, Dirk, Guercilena, Federico, Arcones, Almudena, Rezzolla, Luciano, & Korobkin, Oleg. r-process nucleosynthesis from matter ejected in binary neutron star mergers [On r-process nucleosynthesis from matter ejected in binary neutron star mergers]. United States. doi:10.1103/PhysRevD.96.124005.
Bovard, Luke, Martin, Dirk, Guercilena, Federico, Arcones, Almudena, Rezzolla, Luciano, and Korobkin, Oleg. 2017. "r-process nucleosynthesis from matter ejected in binary neutron star mergers [On r-process nucleosynthesis from matter ejected in binary neutron star mergers]". United States. doi:10.1103/PhysRevD.96.124005. https://www.osti.gov/servlets/purl/1415425.
@article{osti_1415425,
title = {r-process nucleosynthesis from matter ejected in binary neutron star mergers [On r-process nucleosynthesis from matter ejected in binary neutron star mergers]},
author = {Bovard, Luke and Martin, Dirk and Guercilena, Federico and Arcones, Almudena and Rezzolla, Luciano and Korobkin, Oleg},
abstractNote = {Here, 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.},
doi = {10.1103/PhysRevD.96.124005},
journal = {Physical Review D},
number = 12,
volume = 96,
place = {United States},
year = {2017},
month = {12}
}

Works referenced in this record:

Nuclear Ground-State Masses and Deformations
journal, March 1995
  • Moller, P.; Nix, J. R.; Myers, W. D.
  • Atomic Data and Nuclear Data Tables, Vol. 59, Issue 2, p. 185-381
  • DOI: 10.1006/adnd.1995.1002