The formation of compact groups of galaxies. I: Optical properties
The formation of compact groups of galaxies. I: Optical properties
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DOI：
10.1086/116900
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发表时间：
1994-03
期刊：
影响因子：
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通讯作者：
A. Diaferio;M. Geller;M. Ramella
中科院分区：
文献类型：
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作者：
A. Diaferio;M. Geller;M. Ramella
致密星系群(t(Subcr)H(Sub0)约小于0.02)的小穿越时间使得人们很难理解它们为什么是可观测到的。我们的无耗散N体模拟表明，在单个丰富的塌缩群中，不断形成致密的星系群。如果约为1 Gyr，则为特定紧凑型配置的平均寿命。在这个时间尺度上，成员可以合并和/或松散群中的其他星系可以加入紧凑构型。换句话说，紧凑型配置不断被新系统取代。这个过程的频率解释了紧致群的可观性。我们的模型产生了紧凑的组态(紧凑群(CG))，其光学性质与Hickson(1982)的紧致群(HCG)非常相似：(1)CG的成员频率分布与HCG的相似；(2)CG的密度约为松散群的10倍；(3)CG的动力学性质与HCG的非常相似；(4)CG的大多数星系成员不是合并的剩余成员。该模型的关键方面是CG与周围富有的松散群体之间的关系。我们的模型预测了CG的发生频率，对18个富松散类群的初步分析与模型预测是一致的。我们建议对该模型进行进一步的观测测试。
The small crossing time of compact groups of galaxies (t(sub cr)H(sub 0) approximately less than 0.02) makes it hard to understand why they are observable at all. Our dissipationless N-body simulations show that within a single rich collapsing group compact groups of galaxies continually form. The mean lifetime of a particular compact configuration if approximately 1 Gyr. On this time scale, members may merge and/or other galaxies in the loose group may join the compact configuration. In other words, compact configurations are continually replaced by new systems. The frequency of this process explains the observability of compact groups. Our model produces compact configurations (compact groups (CG's) with optical properties remarkably similar to Hickson's (1982) compact groups (HCG's): (1) CG's have a frequency distribution of members similar to that of HCG's; (2) CG's are approximately equals 10 times as dense as loose groups; (3) CG's have dynamical properties remarkably similar to those of HCG's; (4) most of the galaxy members of CG's are not merger remnants. The crucial aspect of the model is the relationship between CG's and the surrounding rich loose group. Our model predicts the frequency of occurrence of CG's. A preliminary analysis of 18 rich loose groups is consistent with the model prediction. We suggest further observational tests of the model.