论文标题
关于银河系的物理大小，球形簇NGC 7089（M 2）
On the physical size of the Milky Way globular cluster NGC 7089 (M 2)
论文作者
论文摘要
我们研究了基于新的深色能量摄像头（DECAM）观测值的银河系的外部区域。产生的背景清洁了恒星密度曲线，揭示了扩展的包络的存在。我们证实了先前的结果，即从集群中心发现了群集恒星，这是最健壮的潮汐半径估计值的三倍。我们还使用了直接N体模拟的结果来与观测值进行比较。我们发现观察到的恒星密度曲线和数值生成的恒星密度曲线之间存在相当良好的一致性。由于存在沿球形簇潮汐尾巴的间隙和子结构，我们仔细研究了雅各比半径以外的外簇区域的结构。我们将分析扩展到了35个球状簇的样本，其中20个带有观察到的潮汐尾巴。我们发现，如果恒星密度曲线遵循功率定律〜r **（-Alpha），则alpha斜率与球状簇存在的质量相关，从某种意义上说，球形群集越大，alpha值就越小。没有观察到的潮汐尾巴，在球状簇中找不到这种趋势。这种现象的起源可能与所提出的所谓潜在逃生者或暗物质迷你山脉中的球形簇形成相关。
We study the outer regions of the Milky Way globular cluster NGC 7089 based on new Dark Energy Camera (DECam) observations. The resulting background cleaned stellar density profile reveals the existence of an extended envelope. We confirm previous results that cluster stars are found out to ~ 1deg from the cluster's centre, which is nearly three times the value of the most robust tidal radii estimations. We also used results from direct N-body simulations in order to compare with the observations. We found a fairly good agreement between the observed and numerically generated stellar density profiles. Because of the existence of gaps and substructures along globular cluster tidal tails, we closely examined the structure of the outer cluster region beyond the Jacobi radius. We extended the analysis to a sample of 35 globular clusters, 20 of them with observed tidal tails. We found that if the stellar density profile follows a power law ~ r**(-alpha), the alpha slope correlates with the globular cluster present mass, in the sense that, the more massive the globular cluster the smaller the alpha value. This trend is not found in globular clusters without observed tidal tails. The origin of such a phenomenon could be related, among other reasons, to the proposed so-called potential escapers or to the formation of globular clusters within dark matter mini-haloes.
