We present a systematic numerical-relativity study of the dynamical ejecta, winds and nucleosynthesis in neutron star merger remnants. Binaries with the chirp mass compatible with GW170817, different mass ratios, and five microphysical equations of state (EOS) are simulated with an approximate neutrino transport and a subgrid model for magnetohydrodynamics turbulence up to 100 milliseconds postmerger. Spiral density waves propagating from the neutron star remnant to the disk trigger a wind with mass flux ${\sim}0.1{-}0.5\,{\rm M_\odot/s}$ persisting for the entire simulation as long as the remnant does not collapse to black hole. This wind has average electron fraction $\gtrsim 0.3$ and average velocity ${\sim}0.1-0.17\,$c and thus is a site for the production of weak $r$-process elements (mass number $A<195$). Disks around long-lived remnants have masses ${\sim}0.1{-}0.2\,{\rm M_\odot}$, temperatures peaking at $\lesssim10\,$MeV near the inner edge, and a characteristic double-peak distribution in entropy resulting from shocks propagating through the disk. The dynamical and spiral-wave ejecta computed in our targeted simulations are not compatible with those inferred from AT2017gfo using two-components kilonova models. Rather, they indicate that multi-component kilonova models including disk winds are necessary to interpret AT2017gfo. The nucleosynthesis in the combined dynamical ejecta and spiral-wave wind in the comparable-mass long-lived mergers robustly accounts for all the $r$-process peaks, from mass number ${\sim}75$ to actinides in terms of solar abundances. Total abundandes are weakly dependent on the EOS, while the mass ratio affect the production of first peak elements.

中文翻译：

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中子星合并 GW170817 的数值相对论模拟：长期残余演化、风、残余盘和核合成

我们对中子星合并残余物中的动力喷射物、风和核合成进行了系统的数值相对论研究。具有与 GW170817 兼容的啁啾质量、不同质量比和五个微物理状态方程 (EOS) 的双星使用近似中微子传输和磁流体动力学湍流子网格模型进行模拟，该模型可在合并后长达 100 毫秒。从中子星残骸传播到圆盘的螺旋密度波触发质量通量 ${\sim}0.1{-}0.5\,{\rm M_\odot/s}$ 的风，只要残骸不会坍缩成黑洞。这种风具有平均电子分数 $\gtrsim 0.3$ 和平均速度 ${\sim}0.1-0.17\,$c，因此是产生弱 $r$-过程元素（质量数 $A<195$ ）。长寿命残骸周围的圆盘质量为 ${\sim}0.1{-}0.2\,{\rm M_\odot}$，温度在 $\lesssim10\, 靠近内边缘的 $MeV 达到峰值，并且具有特征性的双峰由通过磁盘传播的冲击产生的熵分布。在我们的目标模拟中计算的动力学和螺旋波喷射与使用两分量千新星模型从 AT2017gfo 推断的那些不兼容。相反，它们表明包括盘风在内的多分量千新星模型对于解释 AT2017gfo 是必要的。在可比质量的长寿命合并中，动力喷射物和螺旋波风组合中的核合成有力地解释了所有 $r$-过程峰值，从质量数 ${\sim}75$ 到就太阳丰度而言的锕系元素. 总丰度弱依赖于 EOS，