Projecting the likely importance of weak-interaction-driven bulk viscosity in neutron star mergers
Projecting the likely importance of weak-interaction-driven bulk viscosity in neutron star mergers
复制标题
预测弱相互作用驱动的体积粘度在中子星合并中可能的重要性
DOI：
10.1093/mnras/stab2793
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发表时间：
2021
影响因子：
4.8
通讯作者：
Yunes, Nicolás
中科院分区：
文献类型：
--
作者：
Most, Elias R;Harris, Steven P;Plumberg, Christopher;Alford, Mark G;Noronha, Jorge;Noronha-Hostler, Jacquelyn;Pretorius, Frans;Witek, Helvi;Yunes, Nicolás
在这项工作中，我们估计有多少体积粘度驱动的Urca过程可能会影响引力波信号的中子星星合并。在后期的inspiral，我们表明，体积粘度影响的结合能在第四后牛顿秩序。尽管这种效应被引力紧密度的平方所增强，但当只考虑轨道运动本身时，体粘滞系数可能太小而不能在螺旋后期的波形中产生可观察到的效应。然而，在合并后，特征的时间尺度和空间尺度是不同的，可能导致相反的结论。我们后处理的数据，从一个国家的最先进的等质量的二元中子星星合并模拟，以估计整体粘度的影响（这是不包括在模拟本身）。在这种情况下，我们发现，体积粘度可以达到高值的合并区域。我们计算了几个估计，它可能会直接影响所考虑的合并方案的全球动态，并发现它可能变得显着。在不同的合并设想或包括非线性影响的模拟中，可能会产生更大的影响。这种评估是加强了定量比较与相对论重离子碰撞，这种影响已被广泛探讨。
In this work, we estimate how much bulk viscosity driven by Urca processes is likely to affect the gravitational wave signal of a neutron star coalescence. In the late inspiral, we show that bulk viscosity affects the binding energy at fourth post-Newtonian order. Even though this effect is enhanced by the square of the gravitational compactness, the coefficient of bulk viscosity is likely too small to lead to observable effects in the waveform during the late inspiral, when only considering the orbital motion itself. In the post-merger, however, the characteristic time-scales and spatial scales are different, potentially leading to the opposite conclusion. We post-process data from a state-of-the-art equal-mass binary neutron star merger simulation to estimate the effects of bulk viscosity (which was not included in the simulation itself). In that scenario, we find that bulk viscosity can reach high values in regions of the merger. We compute several estimates of how much it might directly affect the global dynamics of the considered merger scenario, and find that it could become significant. Even larger effects could arise in different merger scenarios or in simulations that include non-linear effects. This assessment is reinforced by a quantitative comparison with relativistic heavy-ion collisions where such effects have been explored extensively.