We use recently compiled position and velocity data for the globular cluster and planetary nebula subsystems in NGC?5128, the nearby giant elliptical, to search for evidence of past dwarf-satellite accretion events. Beyond a 10' (~11 kpc) radius in galactocentric distance, we find tentative evidence for four subgroups of globular clusters and four subgroups of planetary nebulae. These each have more than four members within a search radius of 2' and internal velocity dispersion of 40 km s–1, typical parameters for a dwarf galaxy. In addition, two of the globular cluster groupings overlap with two of the planetary nebulae groupings, and two subgroupings also appear to overlap with previously known arc and shell features in the halo light. Simulation tests of our procedure indicate that the probability of finding false groups due to chance is 1%.
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机译:我们使用NGC?5128(附近的巨大椭圆形)中球状星团和行星状星云子系统的最新编译位置和速度数据,来寻找过去的矮卫星增生事件的证据。超过半球中心距半径的10'(〜11 kpc)半径,我们发现了球状星团的四个子组和行星状星云的四个子组的初步证据。它们各自在搜索半径2'之内具有四个以上的成员,内部速度色散为40 km s-1,这是矮星系的典型参数。此外,两个球状星团分组与两个行星状星云分组重叠,并且两个子分组在晕圈光中似乎也与先前已知的弧和壳特征重叠。我们程序的模拟测试表明,由于偶然原因而发现虚假群体的可能性小于1%。
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