arXiv 0812.37232008-12astro-ph

红矮星星系的性质

The nature of red dwarf galaxies

Yu Wang, Xiaohu Yang, H. J. Mo, Frank C. van den Bosch, Neal katz, Anna Pasquali, Daniel H. McIntosh, Simone M. Weinmann

备注：: 9 pages, 8 figures, Accepted for publication in ApJ
发表信息：: Astrophys.J.697:247-257,2009
DOI：: 10.1088/0004-637X/697/1/247

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摘要：

利用从斯隆数字巡天数据第4版中选出的星系群追踪的暗物质晕，我们发现大约1/4的暗星系（$\rmag >-17.05$，以下简称矮星）是它们自己晕中的中心星系，它们不是蓝色的，也不是恒星形成的，正如星系形成的标准模型所预期的那样，而是红色的。相比之下，矮卫星星系的这一比例约为1/2。许多红矮星星系在物理上与更大质量的晕有关。总的来说，大约有$\sim 45$ %的红矮星系作为卫星存在于大质量晕中，而另外$\sim 25$ %的红矮星系的空间分布比其他矮星系更集中于它们最近的大质量晕。我们用模拟星表表明，非卫星矮星系的最红人口分布在其最近的大质量晕维里半径的3倍左右。我们认为，这群矮星系是由穿过其巨大邻居的低质量光环所承载的，并且导致卫星星系变成红色的相同环境效应也是造成这群星系红色的原因。我们没有发现任何显着的径向依赖的人口矮星系的浓度最高，这表明这些星系的运作机制影响的颜色比结构。然而，超过30%的矮星系是红色和孤立的，它们的起源仍然未知。

英文摘要：

Using dark matter halos traced by galaxy groups selected from the Sloan Digital Sky Survey Data Release 4, we find that about 1/4 of the faint galaxies ($\rmag >-17.05$, hereafter dwarfs) that are the central galaxies in their own halo are not blue and star forming, as expected in standard models of galaxy formation, but are red. In contrast, this fraction is about 1/2 for dwarf satellite galaxies. Many red dwarf galaxies are physically associated with more massive halos. In total, about $\sim 45$% of red dwarf galaxies reside in massive halos as satellites, while another $\sim 25$% have a spatial distribution that is much more concentrated towards their nearest massive haloes than other dwarf galaxies. We use mock catalogs to show that the reddest population of non-satellite dwarf galaxies are distributed within about 3 times the virial radii of their nearest massive halos. We suggest that this population of dwarf galaxies are hosted by low-mass halos that have passed through their massive neighbors, and that the same environmental effects that cause satellite galaxies to become red are also responsible for the red colors of this population of galaxies. We do not find any significant radial dependence of the population of dwarf galaxies with the highest concentrations, suggesting that the mechanisms operating on these galaxies affect color more than structure. However, over 30% of dwarf galaxies are red and isolated and their origin remains unknown.

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