恒星级双黑洞自旋研究进展

Progress in Constraining the Origin of Stellar Binary Black Holes via Their Spin Distribution

自2015年以来,人们已经探测到93例恒星级双黑洞并合引力波事件,测量了双黑洞质量、自旋和距离等参数,并获得了其统计分布。不同双黑洞起源机制产生的双黑洞性质分布,特别是自旋分布,会显著不同,其可用来限制双黑洞起源。简单回顾了双星演化和动力学相互作用等双黑洞形成机制及自旋来源;综述了利用自旋限制双黑洞起源的一般方法和常见模型,以及利用LIGO/Virgo引力波数据取得的相关进展,并对未来发展前景进行了展望。

Since the first detection of GW150914,a larger amount of stellar binary black hole(sBBH)mergers have been detected by LIGO/Virgo collaboration with high confidence.By analyzing the gravitational wave(GW)signals,one can obtain crucial physical properties of these sBBH mergers,including their chirp mass,spin,and luminosity distance,etc.The origin of sBBHs may encode in the distribution of these physical properties.Here,the curent status of the study on sBBHs spins is reviewed.First,various formation mechanisms of sBBHs are briefly introduced,and these mechanisms include:1)sBBHs are formed via the evolution of massive binary stars(EMBS channel);2)sBBHs are formed via the dynamical interactions with surrounding(compact)stars in dense stellar clusters(dynamical channel);etc.The origin of spins for sBBHs originated from the black hole formation processes is also introduced.One may expect that the spin distributions resulting from different sBBH formation channels are different.For example,the two components of each sBBH resulting from the EMBS channel have spins more or less aligned with each other,while they may be randomly distributed if the sBBH is resulting from the dynamical channel.Therefore,the spin distribution obtained from GW observations may be used to distinguish the EMBS channel from the dynamical channel and further reveal the origin of sBBHs.The general methods for constraining the origin of sBBHs via their spin distribution are then introduced.The results obtained by recent works using the GW observations of sBBHs(GWTC)are summarized.Finally,a summary and a short prospect are given for the future demography study of the sBBH spins measured by next generation ground-based GW detectors.