论文标题
积聚恒星流的结构
The structure of accreted stellar streams
论文作者
论文摘要
银河系的许多球状簇可能是从与银河系合并的卫星星系中得到的。当这些球状簇容易受到潮汐破坏的影响时，此过程可能已经开始在父卫星内部，导致卫星内的早期出现流。当父卫星与银河系合并时，球状簇及其前合并恒星流在某种程度上会产生混乱的过程。在这里，我们研究了合并后积聚流的属性，因为我们今天使用一系列积聚事件的模拟会看到它。我们发现积聚过程会导致广泛的行为，但通常会将积聚的流散布在天空的宽二维区域上。该行为的范围从一组或更多定义明确的“子流”从合并后的薄流延伸到数十度，到在天空的大部分地区，更广泛地分散的碎屑，这取决于合并的米尔基中心的距离。使用模拟流的模拟GAIA样观测值，我们证明了一个吸积 - 流组件可以解释GD-1流中观察到的离线特征。子流本身看起来像是稀薄的潮汐流本身，似乎与合并后流无关，这增加了以银河系观察到的某些无祖细胞流是在古代合并事件中创建的单个或几个积聚流的一部分。
Many of the Milky Way's globular clusters are likely accreted from satellite galaxies that have long since merged with the Milky Way. When these globular clusters are susceptible to tidal disruption, this process likely starts already inside the parent satellite leading to an early stellar stream within the satellite. When the parent satellite merges with the Milky Way, the globular cluster and its pre-merger stellar stream are accreted in a somewhat chaotic process. Here, we investigate the properties of the accreted stream after the merger as we would see it today using a suite of simulations of accretion events. We find that the accretion process leads to a wide range of behaviors, but generally scatters the accreted stream over a wide, two-dimensional area of the sky. The behavior ranges from a set of a few or more well-defined "sub-streams" extending out from the post-merger thin stream by tens of degrees, to more widely dispersed debris over much of the sky, depending on how close to the center of the MilkyWay the merger happened. Using mock Gaia-like observations of the simulated streams, we demonstrate that an accreted-stream component can explain the off-track features observed in the GD-1 stream. Sub-streams can appear like thin tidal streams themselves that are seemingly unassociated with the post-merger stream, raising the possibility that some of the progenitor-less streams observed in the Milky Way are part of a single or a few accreted streams created in an ancient merger event.
