哈勃序列中孤立星系的人口统计
Demographics of Isolated Galaxies Along the Hubble Sequence
摘要：
低密度区域的孤立星系是重要的，因为它们受星系生长的层次模式以及与扰动的相互作用的影响最小，至少在最后几个Gyr。为了全面了解孤立星系的恒星形成历史，我们构建了一个孤立星系的星表，并在相对密集的环境中进行了比较。这些星系是从SDSS DR 7中绘制的，红移范围为$0.025<z<0.044$。我们进行了目视检查，并按照哈勃分类方案对其形态进行了分类。对于光谱研究，我们利用OSSY星表。我们证实了大多数早期的孤立星系的理解。最显著的附加结果如下。孤立星系以晚型星系为主，其形态分布（E：S0：S：Irr）=（9.9：11.3：77.6：1.2）%.孤立星系中椭圆星系的出现频率仅为对照样本的三分之一。大多数的光度和光谱特性是令人惊讶的相似之间的隔离和比较样品。然而，早期型孤立星系的质量比对照样本中的对应星系小50%，年轻（H $β$）20%。这可以解释为在分层合并范式中不同环境下的不同合并和恒星形成历史的结果。我们提供了一个在线目录的列表和我们的样本星系的属性。
英文摘要：
Isolated galaxies in low-density regions are significant in the sense that they are least affected by the hierarchical pattern of galaxy growth, and interactions with perturbers, at least for the last few Gyr. To form a comprehensive picture of the star formation history of isolated galaxies, we constructed a catalog of isolated galaxies and their comparison sample in relatively denser environments. The galaxies are drawn from the SDSS DR7 in the redshift range of $0.025<z<0.044$. We performed a visual inspection and classified their morphology following the Hubble classification scheme. For the spectroscopic study, we make use of the OSSY catalog. We confirm most of the earlier understanding on isolated galaxies. The most remarkable additional results are as follows. Isolated galaxies are dominantly late type with the morphology distribution (E: S0: S: Irr) = (9.9: 11.3: 77.6: 1.2)\%. The frequency of elliptical galaxies among isolated galaxies is only a third of that of the comparison sample. Most of the photometric and spectroscopic properties are surprisingly similar between isolated and comparison samples. However, early-type isolated galaxies are less massive by 50\% and younger (by H$β$) by 20\% than their counterparts in the comparison sample. This can be explained as a result of different merger and star formation histories for differing environments in the hierarchical merger paradigm. We provide an on-line catalog for the list and properties of our sample galaxies.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
