论文标题
GW190521是否是第一世代的黑洞合并？
Is GW190521 the merger of black holes from the first stellar generations?
论文作者
论文摘要
GW190521挑战了我们对大型恒星后期演变的理解，尤其是配对稳定的影响。我们讨论了低或零金属性的恒星可以保留其大部分氢包膜，直到苏佩尔诺诺娃阶段，避免使用脉冲配对稳定性，并产生一个黑洞，并通过后备质量质量质量。我们在零和低金属性上提出了一系列新的恒星进化模型，该模型使用日内瓦和台面恒星演化代码计算出来，并与现有模型网格进行比较。与较高的金属性模型相比，在0-0.0004范围内具有金属性的模型具有三种偏爱BH质量的特性。这些是（i）较低的质量损失率，（ii）更紧凑的恒星二进制相互作用和（iii）可能的H壳相互作用，从而降低了CO核心质量。我们得出的结论是，GW190521可能是直接由第一世代的大型恒星产生的黑洞的合并。我们的模型表明BH质量高达70-75 MSUN。与对流混合，质量损失，H壳相互作用和配对脉动有关的不确定性可能会将此限制增加到〜85 msun。
GW190521 challenges our understanding of the late-stage evolution of massive stars and the effects of the pair-instability in particular. We discuss the possibility that stars at low or zero metallicity could retain most of their hydrogen envelope until the pre-supernova stage, avoid the pulsational pair-instability regime and produce a black hole with a mass in the mass gap by fallback. We present a series of new stellar evolution models at zero and low metallicity computed with the Geneva and MESA stellar evolution codes and compare to existing grids of models. Models with a metallicity in the range 0-0.0004 have three properties which favour higher BH masses as compared to higher metallicity models. These are (i) lower mass-loss rates during the post-MS phase, (ii) a more compact star disfavouring binary interaction and (iii) possible H-He shell interactions which lower the CO core mass. We conclude that it is possible that GW190521 may be the merger of black holes produced directly by massive stars from the first stellar generations. Our models indicate BH masses up to 70-75 Msun. Uncertainties related to convective mixing, mass loss, H-He shell interactions and pair-instability pulsations may increase this limit to ~85 Msun.
