Massive black hole mergers with orbital information: predictions from the ASTRID simulation
Massive black hole mergers with orbital information: predictions from the ASTRID simulation
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大规模黑洞合并与轨道信息：ASTRID 模拟的预测
DOI：
10.1093/mnras/stac1432
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发表时间：
2022
影响因子：
4.8
通讯作者：
Feng, Yu
中科院分区：
文献类型：
--
作者：
Chen, Nianyi;Ni, Yueying;Holgado, A. Miguel;Matteo, Tiziana Di;Tremmel, Michael;DeGraf, Colin;Bird, Simeon;Croft, Rupert;Feng, Yu
我们研究了来自大体积宇宙学模拟Astrid的大质量黑洞（MBH）合并及其相关的引力波信号。Astrid包括最近更新的星系形成和黑洞模型，MBH种子种群在3 × 104 h − 1 M和3 × 105 h − 1 M之间，以及子网格动力学摩擦（DF）模型，以跟踪MBH动力学下降到1.5 ckpch−1。我们直接从kpc尺度的模拟中计算出MBH轨道的初始偏心率，发现大多数MBH对在数值合并之前的轨道偏心率都在0.7以上。在对以下尺度上的未解决演化进行近似后，我们发现大尺度上的模拟DF占DF引起的总轨道衰减时间的一半以上。双星的硬化时间比DF时间长一个数量级，特别是对于种子质量双星（MBH<2 Mseed）。结果表明，在考虑了未分辨的DF演化和二元硬化后，只有个种子MBH对在z> 3处合并。这些> 3的种子质量合并是在一个有偏见的星系人口与最高的恒星质量。由于Astrid的初始偏心率预测较高，我们估计z> 3 MBH的人口的预期合并率为每年0.3 - 0.7。这比使用圆形轨道假设的预测高出1.75倍。激光干涉仪空间天线事件预计将以类似的速率发生，而种子合并，仅涉及一个种子质量MBH，以及非种子MBH的合并。
We examine massive black hole (MBH) mergers and their associated gravitational wave signals from the large-volume cosmological simulationAstrid.Astridincludes galaxy formation and black hole models recently updated with an MBH seed population between 3 × 104h−1M⊙and 3 × 105h−1M⊙and a sub-grid dynamical friction (DF) model to follow the MBH dynamics down to 1.5 ckpch−1. We calculate the initial eccentricities of MBH orbits directly from the simulation at kpc-scales, and find orbital eccentricities above 0.7 for most MBH pairs before the numerical merger. After approximating unresolved evolution on scales below, we find that the in-simulation DF on large scales accounts for more than half of the total orbital decay time () due to DF. The binary hardening time is an order of magnitude longer than the DF time, especially for the seed-mass binaries (MBH< 2Mseed). As a result, onlyof seed MBH pairs merge atz> 3 after considering both unresolved DF evolution and binary hardening. Thesez> 3 seed-mass mergers are hosted in a biased population of galaxies with the highest stellar masses of. With the higher initial eccentricity prediction fromAstrid, we estimate an expected merger rate of 0.3−0.7 per year from thez> 3 MBH population. This is a factor of ∼7 higher than the prediction using the circular orbit assumption. The Laser Interferometer Space Antenna events are expected at a similar rate, and compriseseed-seed mergers,involving only one seed-mass MBH, andmergers of non-seed MBHs.