Stellar Escape from Globular Clusters. I. Escape Mechanisms and Properties at Ejection
Stellar Escape from Globular Clusters. I. Escape Mechanisms and Properties at Ejection
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DOI：
10.3847/1538-4357/acbcc1
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发表时间：
2022-11
期刊：
影响因子：
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通讯作者：
Newlin C. Weatherford;Fulya Kirouglu;G. Fragione;S. Chatterjee;K. Kremer;F. Rasio
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文献类型：
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作者：
Newlin C. Weatherford;Fulya Kirouglu;G. Fragione;S. Chatterjee;K. Kremer;F. Rasio
球状星团的恒星逃逸理论可以追溯到近世纪，特别是球状星团通过两体弛豫和外部潮汐逐渐蒸发的理论。更猛烈的抛射也可以通过强引力散射、超新星、引力波驱动的合并、潮汐破裂事件和物理碰撞发生，但对许多逃逸机制的全面研究有限。最近来自盖亚太空望远镜的精密运动学数据揭示了银河系（MW）中的许多恒星流，并将许多恒星流的起源追溯到特定的MWGC，突出了进一步研究这些星团中恒星逃逸的必要性。在这项研究中，一系列的第一个，我们奠定了基础，详细的后续比较集群蒙特卡罗GC模型和最新的盖亚数据的外围MWGCs，他们的潮汐尾巴，和相关的流。我们彻底审查从GC的逃逸机制，并研究其相对的逃逸率，喷射速度和逃逸人口统计学的贡献。我们第一次表明，三体双星的形成可能占主导地位的高速喷射从典型的MWGC，可能解释一些超高速恒星的MW。由于它们的质量，黑洞强烈地催化了这一过程，并且它们在可观测的核心坍缩开始时的损失，其特征是陡峭的中心亮度轮廓，显着地减少了三体双星的形成，尽管坍缩后密度增加。我们还表明，即使出生时的热偏心率分布，逃逸双星有显着的非热偏心率与在银河系领域观察到的大致均匀的分布一致。
The theory of stellar escape from globular clusters (GCs) dates back nearly a century, especially the gradual evaporation of GCs via two-body relaxation coupled with external tides. More violent ejection can also occur via strong gravitational scattering, supernovae, gravitational wave-driven mergers, tidal disruption events, and physical collisions, but comprehensive study of the many escape mechanisms has been limited. Recent exquisite kinematic data from the Gaia space telescope has revealed numerous stellar streams in the Milky Way (MW) and traced the origin of many to specific MWGCs, highlighting the need for further examination of stellar escape from these clusters. In this study, the first of a series, we lay the groundwork for detailed follow-up comparisons between Cluster Monte Carlo GC models and the latest Gaia data on the outskirts of MWGCs, their tidal tails, and associated streams. We thoroughly review escape mechanisms from GCs and examine their relative contributions to the escape rate, ejection velocities, and escaper demographics. We show for the first time that three-body binary formation may dominate high-speed ejection from typical MWGCs, potentially explaining some of the hypervelocity stars in the MW. Due to their mass, black holes strongly catalyze this process, and their loss at the onset of observable core collapse, characterized by a steep central brightness profile, dramatically curtails three-body binary formation, despite the increased post-collapse density. We also demonstrate that even when born from a thermal eccentricity distribution, escaping binaries have significantly nonthermal eccentricities consistent with the roughly uniform distribution observed in the Galactic field.