Binaries in Globular Clusters

球状星团是在当地宇宙中所有主要星系中发现的大质量星团，在天体物理学的不同研究领域发挥着关键作用。虽然从历史上看，球状星团被用来限制宇宙的年龄或我们银河系的大小，但现在它们作为恒星形成和恒星演化模型的基准，帮助我们理解星系的组合，甚至可能是解释未来几十年预期的大量引力波数据的关键。事实上，大质量星团的中心已经被确定为黑洞相互发现并合并的最有可能的地点之一。然而，为了了解球状星团作为“引力波工厂”的真正潜力，我们需要了解它们的内部演化。在它的一生中，每个星团成员——可能是黑洞、中子星或发光的恒星——都将经历许多次与其他成员的近距离接触，这可能会彻底改变它的命运，甚至将它从宿主星团中驱逐出去。由于它们的大截面，双星系统在调节星团的相遇率方面起着至关重要的作用，但到目前为止，它们的研究一直受到严峻的挑战。由于新的观测技术和复杂的动力学模型的可用性，我们现在可以大大提高我们对大质量星团内双星的理解。由于恒星密度非常高，对球状星团中有代表性的恒星进行光谱研究长期以来是不可行的。积分场光谱学从根本上改变了这一点。特别是，欧洲南方天文台（ESO）的多单元光谱探测器（MUSE）可以非常有效地分析每个球状星团数万颗恒星的光谱。有了MUSE的观测时间保证，近年来我们对球状星团进行了广泛的调查。这个项目的目标是在我们前所未有的球状星团调查中寻找双星，并结合深层无线电和x射线观测以及动力学模型对它们进行分析。我们特别关注那些我们有大量观测时代的星团，这样我们也可以获得双星的完整轨道解，从而可以探测黑洞的伴星。作为这个项目的结果，我们希望找到以下问题的答案：球状星团中有多少恒星黑洞？球状星团中双星的初始性质是什么？诸如蓝离散星、次亚巨星和低质量x射线双星等奇异天体是如何形成和演化的？

Globular clusters, massive star clusters found within all major galaxies in the local universe, play a pivotal role in different research areas within astrophysics. While historically, globular clusters have been used to constrain the age of the universe or the size of our own Milky Way, nowadays they serve as benchmarks for models of star formation and stellar evolution, help us to understand galaxy assembly, and may even hold the key to interpret the wealth of gravitational wave data expected in the coming decades. In fact, the centers of massive star clusters have been identified as one of the most likely sites for black holes to find each other and merge. However, in order to understand the true potential of globular clusters as "gravitational wave factories", we need understand their internal evolution. Over its lifetime, each cluster member -- may it be a black hole, a neutron star or a luminous star -- will experience a number of close encounters with other members that can drastically alter its fate, yes even eject it from its host cluster. Owing to their large cross sections, binary systems play a crucial role in moderating the encounter rate in star clusters, but their study has been subject to severe challenges so far. Thanks to new observing techniques and the availability of sophisticated dynamical models, we are now in a situation where we can significantly advance our understanding of binary stars inside massive star clusters.Because of the very high stellar densities, spectroscopic studies of representative numbers of stars in globular clusters have long been infeasible. Integral field spectroscopy has changed this fundamentally. In particular, the Multi Unit Spectroscopic Explorer (MUSE) of the European Southern Observatory (ESO) allows spectra of tens of thousands of stars per globular cluster to be analyzed spectroscopically very efficiently. With our guaranteed observing time for MUSE, we have conducted an extensive survey of globular clusters in recent years.The goal of this project is to search for binary stars in our unprecedented survey of globular clusters and also to analyze them in conjunction with deep radio and X-ray observations and dynamical models. We are paying particular attention to those clusters of which we have a large number of observational epochs, so that we can also obtain complete orbit solutions for binary stars, allowing the detection of companion stars to black holes.As a result of this project, we hope to find answers to the following questions:How many stellar black holes are there in globular clusters? What were the initial properties of binary stars in globular clusters? How do exotic objects such as blue straggler, sub-subgiants, and low-mass x-ray binaries form and evolve?