Numerical Relativity Simulations of the Neutron Star Merger GW170817: Long-term Remnant Evolutions, Winds, Remnant Disks, and Nucleosynthesis

• Published in: The Astrophysical journal 2021-01, Vol.906 (2), p.98
• Main Authors: Nedora, Vsevolod, Bernuzzi, Sebastiano, Radice, David, Daszuta, Boris, Endrizzi, Andrea, Perego, Albino, Prakash, Aviral, Safarzadeh, Mohammadtaher, Schianchi, Federico, Logoteta, Domenico
• Format: Article
• Language: English
• Subjects: Abundance; Actinides; Astrophysics; Atomic properties; Average velocity; Binary stars; Computational fluid dynamics; Ejecta; Entropy; Equations of state; Fluid flow; Gravitational wave astronomy; Gravitational waves; Magnetohydrodynamic turbulence; Magnetohydrodynamics; Mass flux; Mass ratios; Mathematical models; Neutrinos; Neutron flux; Neutron stars; Nuclear fusion; Nucleosynthesis; Numerical relativity; R-process; Relativity; Simulation; Star mergers; Stars & galaxies; Stellar evolution; Wave propagation; Wind
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/abc9be

We present a systematic numerical relativity study of the dynamical ejecta, winds, and nucleosynthesis in neutron star (NS) merger remnants. Binaries with the chirp mass compatible with GW170817, different mass ratios, and five microphysical equations of state (EOSs) are simulated with an approximate neutrino transport and a subgrid model for magnetohydrodynamic turbulence up to 100 ms postmerger. Spiral density waves propagating from the NS remnant to the disk trigger a wind with mass flux ∼0.1–0.5 M ⊙ s −1 , which persists for the entire simulation as long as the remnant does not collapse to a black hole. This wind has average electron fraction ≳0.3 and average velocity ∼0.1–0.17 c and thus is a site for the production of weak r -process elements (mass number A