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arXiv 1306.0891astro-ph.COastro-ph.GA
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斯隆数字巡天数据发布7:II中的星系三胞胎。与紧密团体的联系?

Galaxy triplets in Sloan Digital Sky Survey Data Release 7: II. A connection with compact groups?

Fernanda Duplancic, Ana Laura O'Mill, Diego G. Lambas, Laerte Sodré, Sol Alonso

摘要:

我们分析了来自O 'Mill et al.(2012)工作的71个发光星系的三胞胎样本。我们比较的性质的三胞胎和他们的成员与控制样本的紧凑的群体,10个最明亮的成员丰富的集群,和星系对。三重态被限制为具有光谱红移在0.01<z<0.14和Mr<-20.5范围内的成员。我们分析了恒星质量(SM)含量,恒星形成率,Dn(4000)参数和颜色指数,并分析了这些系统的不同的整体性质,总恒星形成活动和整体颜色。我们计算了三重星系的性质是强相关的概率。我们将三重态紧密度定义为成员星系的光占系统总面积的百分比。我们的分析表明,三重星系成员的行为类似于紧凑的集团成员和星系丰富的集群。我们还发现,由3个蓝色的、形成恒星的、年轻的恒星星族星系(蓝色三胞胎)组成的系统很可能是真实的系统,而不是偶然的星系配置。这同样适用于由3个红色,非恒星形成星系组成的三胞胎,显示了这些系统中星系属性的相关性。从作为一个整体的三胞胎的分析,我们得出结论,在一个给定的总SM含量,三胞胎显示出总的恒星形成活动和全球的颜色类似于紧凑的群体。然而,蓝色三胞胎显示出高的总恒星形成活动与较低的SM含量。从系统的紧凑性参数的分析,我们发现,光更集中在三重态比在紧凑的群体。我们认为由3个发光星系组成的三胞胎不应该被认为是具有额外成员的星系对的类似物,而是紧凑群体的自然延伸。

英文摘要:

We analyse a sample of 71 triplets of luminous galaxies derived from the work of O'Mill et al. (2012). We compare the properties of triplets and their members with those of control samples of compact groups, the ten brightest members of rich clusters, and galaxies in pairs. The triplets are restricted to have members with spectroscopic redshifts in the range 0.01<z<0.14 and Mr<-20.5. We analyse the stellar mass (SM) content, the star formation rates, the Dn(4000) parameter and colour index and also analyse different global properties of these systems as total star formation activity and global colours. We calculate the probability that the properties of galaxies in triplets are strongly correlated. We define the triplet compactness as a measure of the percentage of the system total area that is filled by the light of member galaxies. Our analysis suggest that triplet galaxy members behave similarly to compact group members and galaxies in rich clusters. We also find that systems comprising 3 blue, star-forming, young stellar population galaxies (blue triplets) are most probably real systems and not a chance configuration of interloping galaxies. The same holds for triplets composed by 3 red, non star-forming galaxies, showing the correlation of galaxy properties in these systems. From the analysis of the triplet as a whole, we conclude that, at a given total SM content, triplets show a total star formation activity and global colours similar to compact groups. However, blue triplets show a high total star formation activity with a lower SM content. From an analysis of the compactness parameter of the systems we find that light is even more concentrated in triplets than in compact groups. We propose that triplets composed by 3 luminous galaxies, should not be considered as an analogous of galaxy pairs with an extra member, but rather they are a natural extension of compact groups.

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