论文标题
NGC 5128球状簇的新速度测量值超出130 kpc：外晕动力学，子结构和动力学
New Velocity Measurements of NGC 5128 Globular Clusters out to 130 kpc: Outer Halo Kinematics, Substructure and Dynamics
论文作者
论文摘要
我们向NGC 5128附近的麦哲伦和盎格鲁 - 澳大利亚望远镜提出了新的径向速度测量和122个新确认的球状簇（GC），这是NGC 5128周围的122个新确认的球状簇（GC），这是最近可访问的大型早期型Galaxy，当时D = 3.8 MPC。值得注意的是，这些新确认的GC中有28个位于预计Radii> 50'（$ \ gtrsim 54 $ kpc），扩展到$ \ sim 130 $ kpc，在外部光环中，在先前的工作中很少有人确认GC。我们确定了几个在星系的红色巨型分支星形图中可见的GC的GC子集。在某些情况下，这些GC的这些子集在运动学上是冷的，并且可能与这些特定的恒星子结构直接相关并起源于这些。从645个GC的运动学样品组合样品中，我们可以看到所有半径相干旋转的证据，对于金属富含金属的GC亚群，旋转幅度较高。使用示踪剂质量估计器，我们在$ \ sim 120 $ kpc中测量总封闭式质量为$ 2.5 \ pm0.3 \ times 10^{12} m _ {\ odot} $，这将通过即将实施的动态建模来锐化。恒星映射和GC运动学的组合功率使NGC 5128成为持续的基石，用于理解当地组无法访问的质量尺度的星系组件。
We present new radial velocity measurements from the Magellan and the Anglo-Australian Telescopes for 174 previously known and 122 newly confirmed globular clusters (GCs) around NGC 5128, the nearest accessible massive early-type galaxy at D=3.8 Mpc. Remarkably, 28 of these newly confirmed GCs are at projected radii >50' ($\gtrsim 54$ kpc), extending to $\sim 130$ kpc, in the outer halo where few GCs had been confirmed in previous work. We identify several subsets of GCs that spatially trace halo substructures that are visible in red giant branch star maps of the galaxy. In some cases, these subsets of GCs are kinematically cold, and may be directly associated with and originate from these specific stellar substructures. From a combined kinematic sample of 645 GCs, we see evidence for coherent rotation at all radii, with a higher rotation amplitude for the metal-rich GC subpopulation. Using the tracer mass estimator, we measure a total enclosed mass of $2.5\pm0.3 \times 10^{12} M_{\odot}$ within $\sim 120$ kpc, an estimate that will be sharpened with forthcoming dynamical modeling. The combined power of stellar mapping and GC kinematics makes NGC 5128 an ongoing keystone for understanding galaxy assembly at mass scales inaccessible in the Local Group.
