Numerical Relativity Simulations of the Neutron Star Merger GW170817: Long-term Remnant Evolutions, Winds, Remnant Disks, and Nucleosynthesis
Numerical Relativity Simulations of the Neutron Star Merger GW170817: Long-term Remnant Evolutions, Winds, Remnant Disks, and Nucleosynthesis
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DOI：
10.3847/1538-4357/abc9be
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发表时间：
2020-08
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通讯作者：
V. Nedora;S. Bernuzzi;D. Radice;Boris Daszuta;Andrea Endrizzi;A. Perego;Aviral Prakash;M. Safarzadeh;F. Schianchi;D. Logoteta
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作者：
V. Nedora;S. Bernuzzi;D. Radice;Boris Daszuta;Andrea Endrizzi;A. Perego;Aviral Prakash;M. Safarzadeh;F. Schianchi;D. Logoteta
本文对中子星星（NS）合并残留物中的动力学喷出物、风和核合成进行了系统的数值相对论研究。用近似中微子输运和磁流体动力学湍流亚网格模型模拟了与GW 170817兼容的啁啾质量、不同质量比和5个微物理状态方程的双星，并在100 ms后合并.螺旋密度波从NS残骸传播到圆盘，触发了质量通量为0.1-0.5 M·s-1的风，只要残骸不坍缩成黑洞，这种风就会在整个模拟过程中持续存在。这股风的平均电子分数为10.3，平均速度为10.1 -0.17 c，因此是产生弱r过程元素（质量数A < 195）的场所。长寿命的残骸周围有质量为0.1-0.2兆电子伏特，温度在靠近内部边缘的100兆电子伏特处达到峰值，并且由于冲击波在盘中传播而导致熵的特征双峰分布。在我们有针对性的模拟计算的动力学和螺旋波喷出物是不兼容的AT 2017 gfo使用两个组件kilonova模型推断。相反，他们指出，多组分kilonova模型，包括磁盘风是必要的解释AT 2017 gfo。核合成相结合的动力学喷出物和螺旋波风在长期的合并可比的质量强劲占所有的r-过程的峰值，从质量数1075到锕系元素的太阳丰度。总丰度弱依赖于EOS，而质量比影响第一峰元素的产生。
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 < 195). Disks around long-lived remnants have masses ∼0.1–0.2 M ⊙, temperatures peaking at ≲10 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 multicomponent kilonova models including disk winds are necessary to interpret AT2017gfo. The nucleosynthesis in the combined dynamical ejecta and spiral-wave wind in the long-lived mergers of comparable mass robustly accounts for all the r-process peaks, from mass number ∼75 to actinides in terms of solar abundances. Total abundances are weakly dependent on the EOS, while the mass ratio affects the production of first-peak elements.