论文标题
关于小星系系统的性质
On the nature of Small Galaxy Systems
论文作者
论文摘要
我们旨在定义小型星系系统的均匀选择标准，以构建适合于将成对，三胞胎和组的主要特性与四个或更多成员进行比较的目录。为此，我们使用光谱和光度SDSS数据来识别成员数量少的系统。我们研究了这些系统的全球性质及其成员星系的特性，发现组中的星系是系统地变红的，并且具有比星系的恒星形成活性指标较低，而恒星形成星系的比例更高。三胞胎星系呈现在对和组之间的中间趋势。我们还发现，与100kpc更接近的小型系统中星系中星系的恒星形成活性的增强，无论成员数量如何。我们已经对千年模拟得出的SDS模拟目录进行了测试，当考虑到由于纤维碰撞而导致的极端情况时，在小星系系统中发现保守阈值76％的完整性和23％的污染。然而，我们还发现，所获得的结果不太可能受投射效应的影响。我们的研究表明，系统中的额外星系会改变成员星系的性质。在成对中，星系 - 半乳腺相互作用会增加气体密度并触发星爆。但是，三胞胎和组中的重复相互作用可以产生气体剥离，湍流和冲击，从而消除这些系统中的恒星形成。
We aim at defining homogeneous selection criteria of small galaxy systems in order to build catalogues suitable to compare main properties of pairs, triplets, and groups with four or more members. To this end we use spectroscopic and photometric SDSS data to identify systems with a low number of members. We study global properties of these systems and the properties of their member galaxies finding that galaxies in groups are systematically redder and with lower star formation activity indicators than galaxies in pairs which have a higher fraction of star forming galaxies. Triplet galaxies present intermediate trends between pairs and groups. We also find an enhancement of star formation activity for galaxies in small systems with companions closer than 100kpc, irrespective the number of members. We have tested these analysis on SDSS mock catalogues derived from the Millennium simulation, finding as conservative thresholds 76% completeness and a contamination of 23% in small galaxy systems, when considering an extreme case of incompleteness due to fiber collisions. Nevertheless, we also found that the results obtained are not likely affected by projection effects. Our studies suggest that an extra galaxy in a system modify the properties of the member galaxies. In pairs, galaxy-galaxy interactions increases gas density and trigger starbursts. However, repeated interactions in triplets and groups can generate gas stripping, turbulence and shocks quenching the star formation in these systems.
