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arXiv 2008.04333astro-ph.HEgr-qc
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中子星合并GW170817的数值相对论模拟:长期残留演化、风、残留演化和核合成

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

Vsevolod Nedora, Sebastiano Bernuzzi, David Radice, Boris Daszuta, Andrea Endrizzi, Albino Perego, Aviral Prakash, Mohammadtaher Safarzadeh, Federico Schianchi, Domenico Logoteta

摘要:

我们提出了一个系统的数值相对论研究的动力学喷出物,风和核合成的中子星合并残留物。用近似中微子输运和磁流体湍流亚网格模型模拟了与GW 170817兼容的啁啾质量、不同质量比和五个微物理状态方程的双星,并在100毫秒内进行了磁流体湍流模拟.螺旋密度波从中子星遗迹传播到磁盘触发风与质量通量${\sim}0.1{-}0.5\,{\rm M_\odot/s}$持续整个模拟,只要遗迹不崩溃的黑洞。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$A<195$)的场所。围绕着长寿命残留物的尘埃具有质量${\sim}0.1{-}0.2\,{\rm M_\odot}$,温度在靠近内缘的地方达到$\lesssim10\,$ MeV的峰值,并且由于激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AT2017gfo使用两个组件kilonova模型推断。相反,他们指出,包括盘风在内的多分量kilonova模型对于解释AT2017gfo是必要的。核合成相结合的动力喷出物和螺旋波风在相当质量的长寿命合并强劲占所有的$r$过程的峰值,从质量数${\sim}75$的锕系元素的太阳丰度。总丰度对物态方程的依赖性较弱,而质量比影响第一峰元素的产生。

英文摘要:

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.

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