The frequent detection of binary mergers of ∼30 M _⊙ black holes (BHs) by the Laser Interferometer Gravitational-Wave Observatory (LIGO) rekindled researchers’ interest in primordial BHs (PBHs) being dark matter (DM). In this work, we investigated PBHs distributed as DM with a monochromatic mass of 30 M _⊙ and examined the encounter-capture scenario of binary formation, where the densest central region of DM halo dominates. Thus, we paid special attention to the tidal effect by the supermassive black hole (SMBH) present. In doing so, we discovered a necessary tool called loss zone that complements the usage of loss cone. We found that the tidal effect is not prominent in affecting binary formation, which also turned out to be insufficient in explaining the totality of LIGO’s event rate estimation, especially due to a microlensing event constraining the DM fraction in PBH at the mass of interest from near unity to an order smaller. Meanwhile, an early-universe binary formation scenario proves so prevailing that the LIGO signal in turn constrains the PBH fraction below one percent. Thus, people should put more faith in alternative PBH windows and other DM candidates.

激光干涉引力波天文台 (LIGO) 频繁探测到约 30 M⊙黑洞 ( _BH )的二元合并，重新点燃了研究人员对作为暗物质 (DM) 的原始 BH (PBH) 的兴趣。在这项工作中，我们研究了以 DM 形式分布的 PBH，单色质量为 30 M _⊙并检查了双星形成的相遇捕获场景，其中 DM 晕的最密集的中心区域占主导地位。因此，我们特别关注了超大质量黑洞（SMBH）的潮汐效应。在这样做的过程中，我们发现了一个必要的工具，称为损失区，它补充了损失锥的使用。我们发现潮汐效应在影响双星形成方面并不突出，这也不足以解释 LIGO 事件率估计的整体性，特别是由于微透镜事件限制了 PBH 中的 DM 部分从附近感兴趣的质量统一到一个更小的顺序。与此同时，早期宇宙双星形成的情景证明如此普遍，以至于 LIGO 信号反过来将 PBH 分数限制在 1% 以下。因此，