论文标题
通过球状簇的紧密相遇在GD-1流中形成间隙的概率
Probability of forming gaps in the GD-1 stream by close encounters of globular clusters
论文作者
论文摘要
GD-1恒星流的最吸引人的特性之一是存在三个空白。如果这些间隙是通过与暗物质Subhalos的紧密相遇形成的，那么GD-1流将打开一个令人兴奋的窗口，我们可以通过银河系以银色的方式看到深色物质Subhalos的大小，质量和速度分布。但是，为了将GD-1流用作暗物质子结构的探测，我们需要反驳这些差距并不是由于银河系的重型组件的扰动所致。在这里，我们运行了大量的测试粒子模拟，以研究每个已知的球状簇（GC）可以通过使用GAIA EDR3的GD-1流的运动学数据以及完全考虑了观察不确定性的GGD-1流和GCS的运动学数据，从而研究了每个已知的球状簇（GC）可以形成GD-1样间隙。我们发现，所有三个空白的概率均由GCS形成，低至$ 1.7 \ times10^{ - 5} $，而GCS形成的预期差距仅为我们的基金模型中的$ 0.057 $。我们的结果高度分散了GC形成差距的情况。鉴于其他重型perturbers（例如，巨型分子云）在逆行移动的GD-1流中形成差距的可能性甚至较小，我们得出的结论是，如果flyby扰动形成了差距，则Dark Matter Subhalos在GD-1流中至少形成了一个差距。
One of the most intriguing properties of the GD-1 stellar stream is the existence of three gaps. If these gaps were formed by close encounters with dark matter subhalos, the GD-1 stream opens an exciting window through which we can see the size, mass, and velocity distributions of the dark matter subhalos in the Milky Way. However, in order to use the GD-1 stream as a probe of the dark matter substructure, we need to disprove that these gaps are not due to the perturbations from baryonic components of the Milky Way. Here we ran a large number of test particle simulations to investigate the probability that each of the known globular clusters (GCs) can form a GD-1-like gap, by using the kinematical data of the GD-1 stream and GCs from Gaia EDR3 and by fully taking into account the observational uncertainty. We found that the probability that all of the three gaps were formed by GCs is as low as $1.7\times10^{-5}$ and the expected number of gaps formed by GCs is only $0.057$ in our fiducial model. Our result highly disfavors a scenario in which GCs form the gaps. Given that other baryonic perturbers (e.g., giant molecular clouds) are even less likely to form a gap in the retrograde-moving GD-1 stream, we conclude that at least one of the gaps in the GD-1 stream was formed by dark matter subhalos if the gaps were formed by flyby perturbations.
