The landscape of disc outflows from black hole–neutron star mergers
The landscape of disc outflows from black hole–neutron star mergers
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DOI：
10.1093/mnras/staa2209
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发表时间：
2020-05
影响因子：
4.8
通讯作者：
R. Fern'andez;F. Foucart;J. Lippuner
中科院分区：
文献类型：
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作者：
R. Fern'andez;F. Foucart;J. Lippuner
我们研究黑洞（BH）和中子星（NS）合并形成的吸积盘的质量抛射。 LIGO/Virgo 干涉仪的第三次观测提供了 BH-NS 候选事件，但没有产生电磁 (EM) 对应物。 BH-NS 合并带来的广泛的盘配置激发了对参数空间的彻底探索，以改进电磁信号预测。在这里，我们对 BH 吸积盘的粘性演化进行了 27 个高分辨率、轴对称、长期流体动力学模拟，其中包括中微子发射/吸收效应和核反应网络的后处理。在没有磁场的情况下，这些模拟提供了喷射的初始磁盘质量分数的下限。我们发现该分数与圆盘致密性（BH 质量除以初始圆盘半径）呈近乎线性的反相关关系。这种依赖性与流出发射之前吸积的圆盘质量的分数有关，这取决于圆盘相对于最内部稳定圆形轨道的位置。我们还描述了在固定 BH 质量下随着圆盘质量增加而减少喷射分数和减少镧系元素/锕系元素含量的趋势。这种趋势是由于达到弱冻结的时间较长以及中微子吸收在较高盘质量下日益占主导地位的结果。我们估计了在所研究的配置范围内仅可用于为千新星提供动力的圆盘流出的放射性光度，发现了两个数量级的分布。对于大多数 BH-NS 参数空间，圆盘流出贡献远低于 GW190814 的千新星质量上限。
We investigate mass ejection from accretion disks formed in mergers of black holes (BHs) and neutron stars (NSs). The third observing run of the LIGO/Virgo interferometers provided BH-NS candidate events that yielded no electromagnetic (EM) counterparts. The broad range of disk configurations expected from BH-NS mergers motivates a thorough exploration of parameter space to improve EM signal predictions. Here we conduct 27 high-resolution, axisymmetric, long-term hydrodynamic simulations of the viscous evolution of BH accretion disks that include neutrino emission/absorption effects and post-processing with a nuclear reaction network. In the absence of magnetic fields, these simulations provide a lower-limit to the fraction of the initial disk mass ejected. We find a nearly linear inverse dependence of this fraction on disk compactness (BH mass over initial disk radius). The dependence is related to the fraction of the disk mass accreted before the outflow is launched, which depends on the disk position relative to the innermost stable circular orbit. We also characterize a trend of decreasing ejected fraction and decreasing lanthanide/actinide content with increasing disk mass at fixed BH mass. This trend results from a longer time to reach weak freezout and an increasingly dominant role of neutrino absorption at higher disk masses. We estimate the radioactive luminosity from the disk outflow alone available to power kilonovae over the range of configurations studied, finding a spread of two orders of magnitude. For most of the BH-NS parameter space, the disk outflow contribution is well below the kilonova mass upper limits for GW190814.