Formation pathway of Population III coalescing binary black holes through stable mass transfer
Formation pathway of Population III coalescing binary black holes through stable mass transfer
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DOI：
10.1093/mnras/stx757
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发表时间：
2017-01
影响因子：
4.8
通讯作者：
K. Inayoshi;R. Hirai;T. Kinugawa;K. Hotokezaka
中科院分区：
文献类型：
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作者：
K. Inayoshi;R. Hirai;T. Kinugawa;K. Hotokezaka
我们研究了起源于PopIII恒星的恒星质量双星黑洞的形成，并利用梅萨对PopIII双星进行了恒星演化模拟。我们发现，一个显着的比例PopIII二进制形成大规模BBHs通过稳定的质量转移两颗恒星之间的二进制，没有经历共同的信封阶段。我们调查所需的必要条件PopIII二进制形成BBHs合并的哈勃时间内校准的恒星演化模拟的半解析模型。聚结PopIII BBHs的形成效率估计为两个不同的初始条件PopIII二进制大，小的分离，分别。因此，在这两个模型中，总PopIII双星中的$\sim 10\%$仅通过稳定的质量转移形成BBH，并且这些BBH中的$\sim 10\%$由于哈勃时间内的引力波发射而合并。此外，合并BBH的啁啾质量在$15\lesssim M_{\rm chirp}/M_\odot \lesssim 35$上具有平坦分布。这种形成途径的PopIII BBHs大概是强大的，因为稳定的质量传递是不确定性比常见的信封演变，这是人口II BBHs的主要形成渠道。我们还测试的假设，LIGO检测到的BBH合并起源于PopIII恒星使用我们的结果和总数量的PopIII恒星形成的早期宇宙中，从普朗克测量的光学深度推断。我们的结论是，PopIII BBH形成的情况下，可以解释的质量加权合并率的LIGO的O 1事件与最大PopIII形成效率从普朗克测量推断，即使没有BBH形成的不稳定的质量转移或共同的信封阶段。
We study formation of stellar mass binary black holes (BBHs) originating from Population III (PopIII) stars, performing stellar evolution simulations for PopIII binaries with MESA. We find that a significant fraction of PopIII binaries form massive BBHs through stable mass transfer between two stars in a binary, without experiencing common envelope phases. We investigate necessary conditions required for PopIII binaries to form BBHs coalescing within the Hubble time with a semi-analytical model calibrated by the stellar evolution simulations. The formation efficiency of coalescing PopIII BBHs is estimated for two different initial conditions for PopIII binaries with large and small separations, respectively. Consequently, in both models, $\sim 10\%$ of the total PopIII binaries form BBHs only through stable mass transfer and $\sim 10\%$ of these BBHs merge due to gravitational wave emission within the Hubble time. Furthermore, the chirp mass of merging BBHs has a flat distribution over $15\lesssim M_{\rm chirp}/M_\odot \lesssim 35$. This formation pathway of PopIII BBHs is presumably robust because stable mass transfer is less uncertain than common envelope evolution, which is the main formation channel for Population II BBHs. We also test the hypothesis that the BBH mergers detected by LIGO originate from PopIII stars using our result and the total number of PopIII stars formed in the early universe as inferred from the optical depth measured by Planck. We conclude that the PopIII BBH formation scenario can explain the mass-weighted merger rate of the LIGO's O1 events with the maximal PopIII formation efficiency inferred from the Planck measurement, even without BBHs formed by unstable mass transfer or common envelope phases.