Synchrotron Radiation from the Fast Tail of Dynamical Ejecta of Neutron Star Mergers
Synchrotron Radiation from the Fast Tail of Dynamical Ejecta of Neutron Star Mergers
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DOI：
10.3847/1538-4357/aadf92
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发表时间：
2018-03
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影响因子：
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通讯作者：
K. Hotokezaka;K. Kiuchi;M. Shibata;E. Nakar;T. Piran
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作者：
K. Hotokezaka;K. Kiuchi;M. Shibata;E. Nakar;T. Piran
我们通过高分辨率数值相对论模拟发现，中子星合并的动力喷射物的尾部延伸到快于 0.7c 的温和相对论速度。该快尾的动能约为 1047–1049 erg，具体取决于中子星状态方程和双星质量。这条快尾与周围星际介质 (ISM) 相互作用产生的同步加速器耀斑可以为 GW170817 之后观测到的非热发射提供动力，前提是 ISM 密度为 、两颗中子星质量大致相等且中子星状态方程较软（中子星半径小）。这种情况的一般预测之一是冷却频率在几个月到一年的时间尺度上穿过 X 射线波段，导致 X 射线光曲线出现冷却中断。虽然最近通过超长基线干涉测量（VLBI）解决的超光速运动观测排除了动态喷射物的情况，但本文描述的模型是通用的，可以应用于未来的中子星合并事件。
We find, using high-resolution numerical relativistic simulations, that the tail of the dynamical ejecta of neutron star mergers extends to mildly relativistic velocities faster than 0.7c. The kinetic energy of this fast tail is ∼1047–1049 erg, depending on the neutron star equation of state and on the binary masses. The synchrotron flare arising from the interaction of this fast tail with the surrounding interstellar medium (ISM) can power the observed nonthermal emission that followed GW170817, provided that the ISM density is , the two neutron stars had roughly equal masses and the neutron star equation of state is soft (small neutron star radii). One of the generic predictions of this scenario is that the cooling frequency crosses the X-ray band on a timescale of a few months to a year, leading to a cooling break in the X-ray light curve. While the recent observation of the superluminal motion resolved by very long baseline interferometry (VLBI) rules out the dynamical ejecta scenario, the model described in this paper is generic and can be applied for future neutron star merger events.