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arXiv 0812.1580astro-ph
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紧群理论与实践- III。斯隆数字巡天第六次数据发布中的致密星系群

Compact groups in theory and practice - III. Compact groups of galaxies in the Sixth Data Release of the Sloan Digital Sky Survey

Alan McConnachie, David Patton, Sara Ellison, Luc Simard

摘要:

我们提出了最大的公开可用的目录紧凑的星系群确定使用希克森的原始选择标准,从斯隆数字巡天(SDSS)的第六次数据发布(DR 6)。我们确定了2297个紧群,直到极限值r = 18(~ 0.24群度^{-2}),74791个紧群,直到极限值r = 21(~ 6.7群度^{-2})。这代表了SDSS DR 6中所有星系的0.9%。由于光度计总误差的污染已被删除的明亮的样本组,我们估计它是存在于大样本中的14%的水平。光谱信息可用于4131星系的明亮目录(43%的完整性),我们发现,这些群体的中值红移是z_{med} = 0.09。明亮星表中致密星群的视向速度色散中值为sigma_{LOS} ~ 230 km/s,典型的星系间距为50 - 100 kpc量级。我们表明,确定为成员的插足星系群的分数与我们以前的研究模拟星系目录的预测是很好的协议,我们演示了如何选择紧凑的群体,这样的插足分数是很好的定义和最小化。这个观测数据集是理想的大型统计研究的紧凑群体,环境对星系演化的作用,以及星系相互作用在确定星系形态的影响。

英文摘要:

We present the largest publicly available catalogue of compact groups of galaxies identified using the original selection criteria of Hickson, selected from the Sixth Data Release (DR6) of the Sloan Digital Sky Survey (SDSS). We identify 2297 compact groups down to a limiting magnitude of r = 18 (~0.24groups degree^{-2}), and 74791 compact groups down to a limiting magnitude of r = 21 (~6.7groups degree^{-2}). This represents 0.9% of all galaxies in the SDSS DR6 at these magnitude levels. Contamination due to gross photometric errors has been removed from the bright sample of groups, and we estimate it is present in the large sample at the 14% level. Spectroscopic information is available for 4131 galaxies in the bright catalogue (43% completeness), and we find that the median redshift of these groups is z_{med} = 0.09. The median line-of-sight velocity dispersion within the compact groups from the bright catalogue is sigma_{LOS} ~ 230km/s and their typical inter-galactic separations are of order 50 - 100kpc. We show that the fraction of groups with interloping galaxies identified as members is in good agreement with the predictions from our previous study of a mock galaxy catalogue, and we demonstrate how to select compact groups such that the interloper fraction is well defined and minimized. This observational dataset is ideal for large statistical studies of compact groups, the role of environment on galaxy evolution, and the effect of galaxy interactions in determining galaxy morphology.

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