紧群理论与实践- II。比较观测到的和预测的致密星系群的性质
Compact groups in theory and practice - II. Comparing the observed and predicted nature of galaxies in compact groups
摘要：
我们研究的性质的星系在紧凑的群体中确定的模拟星系目录的基础上千年运行模拟。在投影中确定的群体的整体性质与最佳观测约束基本一致。然而，只有~30%的这些模拟群体被发现是真正紧凑的3维，这表明闯入者强烈影响我们观察到的理解的性质的星系在紧凑的群体。这些模拟预测，真正的致密星系群是一个极其均匀的群体，几乎完全局限于红色序列：它们最好被描述为“红色和死亡”的椭圆星系。当包括闯入者时，人口变得更加异质，由于更蓝，恒星形成，富含气体，晚型星系被错误地识别为紧凑的群成员。这些模型表明，通过红移选择成员，使得该组的视线速度色散小于1000 km/s，显着减少污染到30%的水平。根据星系颜色选择成员，这是一种经常用于星系团的技术，预计也会大大减少紧凑组研究的污染率。
英文摘要：
We examine the properties of galaxies in compact groups identified in a mock galaxy catalogue based upon the Millennium Run simulation. The overall properties of groups identified in projection are in general agreement with the best available observational constraints. However, only ~30% of these simulated groups are found to be truly compact in 3 dimensions, suggesting that interlopers strongly affect our observed understanding of the properties of galaxies in compact groups. These simulations predict that genuine compact group galaxies are an extremely homogeneous population, confined nearly exclusively to the red sequence: they are best described as `red and dead' ellipticals. When interlopers are included, the population becomes much more heterogeneous, due to bluer, star-forming, gas-rich, late-type galaxies incorrectly identified as compact group members. These models suggest that selection of members by redshift, such that the line-of-sight velocity dispersion of the group is less than 1000 km/s, significantly reduces contamination to the 30% level. Selection of members by galaxy colour, a technique used frequently for galaxy clusters, is also predicted to dramatically reduce contamination rates for compact group studies.
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