The impact of mass uncertainties on the r-process nucleosynthesis in neutron star mergers

Abstract

Theoretical predictions of element yields from the rapid neutron capture (r-) process are subject to large uncertainties due to incomplete knowledge of nuclear properties and approximative hydrodynamical modeling of matter ejection. A major source of uncertainty in determining ejecta composition and radioactive decay heat is the lack of nuclear mass data for exotic neutron-rich nuclei produced during neutron irradiation. We examine both model (systematic) and parameter (statistical) uncertainties affecting nuclear mass predictions and their impact on r-process nucleosynthesis, and consequently, the composition of neutron star merger ejecta. To estimate the effect of model uncertainties, we consider five nuclear mass models that accurately describe known masses. We also use a backward-forward Monte Carlo method to estimate uncorrelated uncertainties from local variations in model parameters, constraining them to experimentally known masses before propagating them to unknown masses of neutron-rich nuclei. These mass uncertainties are then applied to a 1.38-1.38 M${}_{\odot }$ neutron star merger model, considering a wide range of ejecta trajectories. We find that uncorrelated parameter uncertainties lead to ejected abundance uncertainties of 20% up to A $\simeq$ 130, 40% between A=150 and 200, with peaks around A $\simeq$ 140 and A $\simeq$ 203, leading to deviations of 100-300%. While correlated model uncertainties generally exceed parameter uncertainties for most nuclei, both have a significant impact on heavy element production. Overall, improvements in nuclear models are essential to reducing uncertainties in r-process predictions. Both correlated model uncertainties and coherent determination of parameter uncertainties are crucial for sensitivity analysis in r-process nucleosynthesis.

12 pages, 13 Figures. arXiv admin note: text overlap with arXiv:2303.06366 by other authors

References in corpus (9)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• Comprehensive nucleosynthesis analysis for ejecta of compact binary mergers
• Surface diffuseness correction in global mass formula
• Identification of strontium in the merger of two neutron stars
• The History of R-Process Enrichment in the Milky Way
• Databases and tools for nuclear astrophysics applications BRUSsels Nuclear LIBrary (BRUSLIB), Nuclear Astrophysics Compilation of REactions II (NACRE II) and Nuclear NETwork GENerator (NETGEN)
• Modelling the spectra of the kilonova AT2017gfo -- I: The photospheric epochs
• Fission fragment distributions and their impact on the r-process nucleosynthesis in neutron star mergers

Cited by in corpus (3)

• Impact of in situ nuclear networks and atomic opacities on neutron star merger ejecta dynamics, nucleosynthesis, and kilonovae
• Nuclear astrophysics
• Fingerprints of triaxiality in the charge radii of neutron-rich Ruthenium