Early-type galaxies in low-density environments
Early-type galaxies in low-density environments
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DOI：
10.1046/j.1365-8711.2002.05897.x
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发表时间：
2002-07
影响因子：
4.8
通讯作者：
H. Kuntschner;Russell J. Smith;M. Colless;R. Davies;Raven Kaldare;A. Vazdekis
中科院分区：
文献类型：
--
作者：
H. Kuntschner;Russell J. Smith;M. Colless;R. Davies;Raven Kaldare;A. Vazdekis
我们描述了一个在低密度环境中客观定义的早期类型星系的样本的构建和研究。样本星系是从最近完成的红移测量中挑选出来的，使用了统一和容易量化的隔离标准，并从天空区域∼700°2到深度7 000公里S−1和视星等极限Bj16.1。它们的早期类型(E/S0)形态被随后的CCD成像所证实。九个样本星系中有五个显示出形态特征的迹象，如潮汐碎片或蓝色环状核环。我们证实，E/S0星系在低密度区是罕见的，仅占此类环境中星系总数的8%。(≈)我们介绍了样本中九个星系的光谱观测，这些观测与更新的恒星群模型一起用于研究恒星形成历史。我们的谱线强度分析是在4.1˚A的较高光谱分辨率下进行的，通过与Fornax星系团E/SOS样本(相同分析)的比较，研究了环境对早期类型星系演化的影响。这两个样本的结果与半解析星系形成模型的预测进行了比较。从[O II]λ3727发射的强度，我们推断-
We describe the construction and study of an objectively defined sample of early-type galaxies in low-density environments. The sample galaxies are selected from a recently completed redshift survey using uniform and readily quantified isolation criteria, and are drawn from a sky area of ∼700 deg 2 , to a depth of 7000 km s −1 and an apparent magnitude limit of bJ 16.1. Their early-type (E/S0) morphologies are confirmed by subsequent CCD imaging. Five out of the nine sample galaxies show signs of morphological peculiarity such as tidal debris or blue circumnuclear rings. We confirm that E/S0 galaxies are rare in low-density regions, accounting for only ≈8 per cent of the total galaxy population in such environments. We present spectroscopic observations of nine galaxies in the sample, which are used, in conjunction with updated stellar population models, to investigate star formation histories. Our line-strength analysis is conducted at the relatively high spectral resolution of 4.1 ˚ A. Environmental effects on early-type galaxy evolution are investigated by comparison with a sample of Fornax cluster E/S0s (identically analysed). Results from both samples are compared with predictions from semi-analytic galaxy formation models. From the strength of [O II]λ3727 emission we infer ‐