标题： 合并通过双核演化形成的双黑洞 显示英文标题

标题： Merging binary black holes formed through double-core evolution

摘要： 到目前为止，随着LIGO-Virgo-KAGRA（LVK）合作组织报告的近100个双黑洞（BH）合并事件的探测，各种合并事件的形成通道已被广泛研究。我们在此系统地研究了一种替代的形成情景，即通过双氦星（以下简称双核演化通道）形成的双黑洞（BBHs）。在这种情景中，两颗氦星（富氦星）可能是经典孤立双星演化情景的结果，涉及或不涉及共同包层阶段（即CE通道和稳定质量转移通道），或者可能是化学均匀演化的高质密近距离双星（即CHE通道）。我们进行了详细的恒星结构和双星演化计算，考虑了富氦星的内部差分旋转和质量损失，以及双星中的潮汐相互作用。对于双星中质量相等的富氦星，我们发现潮汐作用在零年龄氦主序星（ZAHeMS：富氦星开始在核心燃烧氦的时间，类似于核心氢燃烧的ZAMS）上开始起作用，初始轨道周期不超过1.0天，这取决于初始金属丰度。除了恒星的质量损失率和双星中的潮汐相互作用外，我们发现当考虑来自较高金属丰度环境的黑洞前身星时，角动量输运效率在决定最终黑洞自旋中的作用变得更加强烈。我们强调，双核演化情景并不总能产生快速自转的BBHs，并将LVK报告的BBHs特性与我们的模型进行比较。 显示英文摘要

摘要： To date, various formation channels of merging events have been heavily explored with the detection of nearly 100 double black hole (BH) merger events reported by the LIGO-Virgo-KAGRA (LVK) Collaboration. We here systematically investigate an alternative formation scenario, i.e., binary BHs (BBHs) formed through double helium stars (hereafter double-core evolution channel). In this scenario, the two helium stars (He-rich stars) could be the outcome of the classical isolated binary evolution scenario involving with and without common-envelope phase (i.e., CE channel and stable mass transfer channel), or alternatively of massive close binaries evolving chemically homogeneously (i.e., CHE channel). We perform detailed stellar structure and binary evolution calculations that take into account internal differential rotation and mass loss of He-rich stars, as well as tidal interactions in binaries. For double He-rich stars with equal masses in binaries, we find that tides start to be at work on the Zero Age Helium Main Sequence (ZAHeMS: the time when a He-rich star starts to burn helium in the core, which is analogous to ZAMS for core hydrogen burning) for initial orbital periods not longer than 1.0 day, depending on the initial metallicities. Besides the stellar mass loss rate and tidal interactions in binaries, we find that the role of the angular momentum transport efficiency in determining the resulting BH spins, becomes stronger when considering BH progenitors originated from a higher metal-metallicity environment. We highlight that double-core evolution scenario does not always produce fast-spinning BBHs and compare the properties of the BBHs reported from the LVK with our modeling.