大质量双星演化和致密星双星的形成

The evolution of massive binaries can be related to many high energy astrophysical phenomena，investigations on these binaries help understand the physical laws under some extreme conditions. During the massive binary evolution, the mass transfer efficiency will directly influence the masses of binary components and the separation of binary orbit, and then change the properties of binary products. In this project we want to explore the processes of mass transfer during the massive binary evolution and the statistical distributions of binary products (compact star binaries). First we research the progenitor evolution of a special WR+O binary (WR 35a), and discuss the mass transfer efficiency during the binary evolution. Secondly we use the stellar evolution code to calculate the massive binary evolution, and will obtain a lot of WR+O binaries with different binary parameters, then compare the calculated and observed parameter distributions of WR+O binaries to constrain the mass transfer efficiencies (mass transfer models). Finally we consider different mass transfer models and use the binary population synthesis code to calculated the parameter distributions of compact star binaries, then constrain the mass transfer models by comparing with the observations, and give the expected birthrates and parameter distributions of compact star binaries. Our calculated results can be used as the theoretical support for future observations of large-scale scientific facilities, e.g. HXMT and FAST.

大质量双星的演化与众多的高能天体物理现象相关，对其研究有助于人们理解某些极端条件下的物理规律。大质量双星演化过程中的物质转移效率会直接影响双星成分的质量和双星的轨道间距，继而改变演化产物的性质。本项目的目的是探讨大质量双星演化时的物质转移过程以及演化产物（致密星双星）的统计分布。首先，我们研究一个特殊的WR＋O双星（WR 35a）的前身星演化，讨论双星演化时的物质转移效率；然后，我们利用恒星演化程序计算大质量双星的演化，得到大量具有不同参数的WR+O双星，再将计算和观测的双星参数进行比较来限制双星演化时的物质转移效率（物质转移模型）；最后，考虑不同的物质转移模型，使用双星星族合成程序计算致密星双星的参数分布，再与观测相结合来限制物质转移模型，并给出致密星双星预期的诞生率和参数分布。我们研究的结果可以为我国未来的大科学装置（如HXMT、FAST）的观测提供理论支撑。

本项目研究了大质量双星演化过程中的物质转移效率、双中子星系统形成、银河系内黑洞/脉冲星双星、中子星/氦星双星极亮X射线源、分离黑洞双星的统计性质。我们发现（1）大质量双星演化时旋转依赖的物质转移模型能够很好地匹配沃尔夫-拉叶星/O型星双星的观测结果；（2）双中子星系统在轨道周期接近1天附近可以两个子类：短周期的系统主要是经历大质量X射线双星相形成的，而宽周期的系统是历经双氦星双星阶段形成的；（3）银盘内大约有3-80个黑洞/脉冲星双星，其中约有10%能被FAST探测到；（4）中子星/氦星双星系统对极亮X射线源星族能有显著贡献，在银河系类似星系中大约有中子星/氦星极亮X射线源；（5）分离黑洞双星是由伴星质量较小的双星系统主导的，它们的数目超过4000。我们的结果可以为我们的大科学装置（如HXMT、FAST）的观测提供理论支撑。