大质量恒星数目稀少，演化时标短，缺乏观测数据，导致几十年以来大质量恒星研究进展缓慢。现阶段对大质量恒星演化及黑洞详细的形成过程存在较大争议，主要包括大质量恒星的星风物质损失率、双星物质转移过程、超新星的爆炸机制、以及双黑洞的形成通道等问题。aLIGO首次探测到恒星级双黑洞并合的引力波信号不但验证了爱因斯坦上个世纪的预言，而且证实了大质量双黑洞的存在。到目前为止，aLIGO和Virgo已经探测到了十个恒星级双黑洞并合产生的引力波事件以及一个双中子星并合产生的引力波事件。本文采用恒星演化程序MESA（Modules for Experiments in Stellar Astrophysics）研究了孤立双星演化形成双黑洞，包括恒星星风、物质转移和超新星爆炸等过程。在我们的研究中，主星初始质量为20-80 M⊙，次星初始质量范围为14-72 M⊙，金属丰度为0.0001-0.002之间，双星初始质量比为0.7-0.9。双星系统通过稳定物质转移通道（即不包含公共包层演化阶段），大多数恒星没有经历超新星爆炸，直接塌缩形成黑洞，最终形成总质量在~15-110 M⊙之间的双黑洞。形成的双黑洞并合时标强烈依赖于初始轨道周期，只有初始轨道周期小于5天的双星系统演化形成的双黑洞通过引力波辐射损失角动量，最终可能在哈勃时标内并合。初始轨道周期大于5天的情况，最终形成的双黑洞并合时标超过哈勃时标。将我们得到的结果与目前已经探测到的引力波事件进行对比后发现我们的结果可以解释部分引力波事件，此外我们还展示了类似GW150914引力波事件的详细形成通道。
其他摘要
Due to the short life time, there is rare observation data for massive stars, which makes the slow progress in the massive stars area for the last decades. The detail evolution of massive stars and the formation of black holes are still an open question. The main controversial issues were the stellar winds of massive stars, the mass transfer process, the supernova explosion mechanism, and the formation of binary black hole, and so on. The first gravitational wave event coming from merging of two stellar-mass binary black holes detected by aLIGO not only confirmed the existence of massive double black hole, but also supported the prediction of Einstein theories. Up to now, aLIGO and Virgo have confidently detected gravitational waves from ten stellar-mass binary black hole mergers and a binary neutron star inspiral. In this paper, we use the stellar evolution code MESA (Modules for Experiments in Stellar Astrophysics) to conduct the numerical simulations for the formation of binary black holes resulted from the evolution of isolated massive binaries, in which some physical processes such as the mass-loss, the mass transfer and accretion, and supernova explosions are taken into account. In our models, the initial mass of primary stars are taken in the range of 20-80 M⊙, the initial mass of secondary stars are ranged from 14 to 72 M⊙, the metallicity is ranged from 0.0001 to 0.002, and the mass ratio are selected to be 0.7, 0.8 and 0.9, respectively. Massive stars binary systems will form double black holes with a total mass about of 15-110 M⊙ by isolated binary evolution that only undergoes stable mass transfer excluding the common envelope phase. Most massive stars do not undergo supernova explosions, they are directly collapse to be black holes at last. After the formation of the two black holes, the merger time highly depends on their initial orbital period. Only the binary black holes formed from the systems with an initial period less than 5 days might be merged within the Hubble time by angular momentum loss due to gravitational wave radiation. binary black holes with a long orbital period cannot merge within the Hubble time. Based on the comparison of our results with the detected gravitational wave events, we find that some detection of gravitational wave events detected by aLIGO and Virgo can be explained through our models. In addition, we showed that detailed formation channel of the source gravitational wave events as GW150914.
修改评论