Velocity Dispersion of the GD-1 Stellar Stream
Velocity Dispersion of the GD-1 Stellar Stream
复制标题
DOI：
10.3847/2041-8213/abf491
复制
发表时间：
2020-11
期刊：
影响因子：
--
通讯作者：
M. G. Gialluca;R. Naidu;A. Bonaca
中科院分区：
文献类型：
--
作者：
M. G. Gialluca;R. Naidu;A. Bonaca
潮汐溶解的球状星团形成了稀薄的恒星流，保存了它们过去演化的历史记录。我们报告了GD-1恒星流的径向速度色散为2.1 ± 0.3 km s−1，使用了43个光谱确认的成员样本。GD-1型流速频散在所测的15°跨度内是恒定的。我们还测量了邻近GD-1主流的支线的速度分散，并在支线的尖端发现了类似的值。令人惊讶的是，该地区的支线更接近流出现动态冷比主流。GD-1气流的未扰动模型的速度色散为0.5km s−1，表明GD-1经历了动力加热。来自球状星团的恒星流，在它们到达银河系之前，围绕着一个具有核心密度分布的矮星系运行，预计已经经历了与GD-1中观察到的速度色散相匹配的加热量。这表明GD-1已经被吸积，并且其原始宿主星系的印记，包括其暗物质晕的内部斜坡，今天仍然可以在流中观察到。
Tidally dissolved globular clusters form thin stellar streams that preserve a historical record of their past evolution. We report a radial velocity dispersion of 2.1 ± 0.3 km s−1 in the GD-1 stellar stream using a sample of 43 spectroscopically confirmed members. The GD-1 velocity dispersion is constant over the surveyed ≈15° span of the stream. We also measured velocity dispersion in the spur adjacent to the main GD-1 stream, and found a similar value at the tip of the spur. Surprisingly, the region of the spur closer to the stream appears dynamically colder than the main stream. An unperturbed model of the GD-1 stream has a velocity dispersion of ≈0.5 km s−1, indicating that GD-1 has undergone dynamical heating. Stellar streams arising from globular clusters, which prior to their arrival in the Milky Way, orbited a dwarf galaxy with a cored density profile are expected to have experienced the amount of heating required to match the velocity dispersion observed in GD-1. This suggests that GD-1 has been accreted and that imprints of its original host galaxy, including the inner slope of its dark matter halo, remain observable in the stream today.