论文标题
潮汐锁定的巨大二进制恒星中的内部循环 - 双黑洞形成的后果
Internal circulation in tidally locked massive binary stars -- Consequences for double black hole formation
论文作者
论文摘要
在潮汐变形的二进制恒星中预测稳态循环电流，据信这是双黑孔合并事件的祖细胞。这项工作旨在定量地表征潮汐锁定二进制系统组件中的稳态循环电流，并探索此类电流对数值模型的影响。先前描述单个旋转星和二进制恒星循环的结果用于推导潮汐锁定二进制文件内部循环的新处方。我们在数值上探讨了该处方对25至100个太阳质量的二元系统的效果。当比较单个旋转恒星和二进制恒星的径向方向上的循环速度时，发现二进制恒星中的平均循环速度可以描述为单个旋转恒星中循环速度的增强。这种速度增强是一个简单的功能，具体取决于二进制组件的质量，当组件具有相等的质量时，速度约为大约两个。发现与标准循环方案相比，具有有效的轨道周期，较低的原始质量和较低的质量比的系统，通过有效混合而导致双氦星的形成。考虑到针对初级质量，初始期和质量比的适当分布，具有增强混合的模型预测了在参数空间中产生的双氦星的2.4倍，而不是没有模型。我们得出的结论是，伴侣诱导的循环的影响对近二进制黑洞的形成具有很大的影响。预测的检测率不仅会增加，而且当考虑伴随诱导的循环时，质量比低至0.8的双黑孔系统可能会形成0.8。
Steady-state circulation currents are predicted in tidally deformed binary stars, which are believed to be progenitors of double black-hole merger events. This work aims to quantitatively characterise the steady-state circulation currents in components of a tidally locked binary system and to explore the effects of such currents on numerical models. Previous results describing the circulation in a single rotating star and a binary star are used to deduce a new prescription for the internal circulation in tidally locked binaries. We explore the effect of this prescription numerically for binary systems with primary masses between 25 and 100 solar masses. When comparing circulation velocities in the radial direction for the single rotating star and binary star, it is found that the average circulation velocity in the binary star may be described as an enhancement to the circulation velocity in a single rotating star. This velocity enhancement is a simple function depending on the masses of the binary components and amounts to a factor of approximately two when the components have equal masses. It is found that the ehancement causes the formation of double helium stars through efficient mixing to occur for systems with higher initial orbital periods, lower primary masses and lower mass ratios, compared to the standard circulation scenario. Taking into account appropriate distributions for primary mass, initial period and mass ratio, models with enhanced mixing predict 2.4 times more double helium stars being produced in the parameter space than models without. We conclude that the effects of companion-induced circulation have strong implications for the formation of close binary black holes. Not only do the predicted detection rates increase but double black-hole systems with mass ratios as low as 0.8 may be formed when companion-induced circulation is taken into account.
