长城星系演化的快照：z=0时Nurture的作用
A snapshot on galaxy evolution occurring in the Great Wall: the role of Nurture at z=0
摘要：
为了定量分析环境对z=0星系演化的贡献，我们利用Sloan数字巡天（SDSS）的DR 7星表重建了后发座超星系团420平方度内4132个星系的三维分布，其中包括两个富星系团（Coma和A1367），几个组，和许多附属结构属于“长城”，在大约100 Mpc的距离。在这个距离上，星系普查完成到Mi=-17.5等，即比M* 暗约4等。星系的形态分类为早期（椭圆形）和晚期（螺旋形）进行了检查个人SDSS图像和光谱。每个星系周围的密度都是在半径为1 Mpc、半长为1000 km/s的圆柱体中确定的。本文导出了Bins形态类型星系在δ {1，1000} <= 0的四个密度-对比度阈值下的色-光度关系（UL =宇宙网络）; 0 < delta{1，1000} <= 4（L =松散的群体）; 4 < delta{1，1000} <= 20（H =大群体和集群的外围）和delta{1，1000} > 20（UH =集群的核心）。早型星系的比例随过密度的对数增加而增加。一个由早型星系组成的定义明确的“红序列”存在于所有高光度环境中，但在最低密度环境中缺乏低光度（矮）星系。相反，低光度孤立星系主要是晚型。换句话说，低光度分布的一端主要是由星团和星系团中的红色dE星系和密度最低的区域中的矮蓝色无定形系统。在z=0时，我们发现了由环境（培育）引起的强烈进化的证据。当居住在低密度环境中的恒星形成矮星系迁移到无定形的被动矮椭圆星系时，大部分转化都发生在低光度下。该机制涉及由于气体剥离而抑制恒星形成，而没有显着的质量增长，如Boselli等人（2008 a）所提出的。这个过程在密度增加的环境中更有效和快速。在最高密度的环境中（在星团周围），恒星形成的截断发生得足够快（大约1亿年），从而在星系光谱中产生恒星爆发后的特征。PSB星系，实际上被发现明显地聚集在最大的动力学单元周围，代表了恒星形成孤立星系的残余，这些星系在过去0.5-1.5 Gyrs的星系团中的恒星形成受到强烈抑制，并且是未来dEs的祖先。
英文摘要：
With the aim of quantifying the contribution of the environment on the evolution of galaxies at z=0 we have used the DR7 catalogue of the Sloan Digital Sky Survey (SDSS) to reconstruct the 3-D distribution of 4132 galaxies in 420 square degrees of the Coma supercluster, containing two rich clusters (Coma and A1367), several groups, and many filamentary structures belonging to the "Great Wall", at the approximate distance of 100 Mpc. At this distance the galaxy census is complete to Mi=-17.5 mag, i.e. approx 4 mag fainter than M*. The morphological classification of galaxies into early- (ellipticals) and late-types (spirals) was carried out by inspection of individual SDSS images and spectra. The density around each galaxies was determined in cylinders of 1 Mpc radius and 1000 km s^-1 half length. The color-luminosity relation was derived for galaxies in bins morphological type and in four thresholds of galaxy density-contrast, ranging from delta{1,1000} <= 0 (UL = the cosmic web); 0 < delta{1,1000} <= 4 (L = the loose groups); 4 < delta{1,1000} <= 20 (H = the large groups and the cluster's outskirts) and delta{1,1000} > 20 (UH = the cluster's cores). The fraction of early-type galaxies increases with the log of the over-density. A well defined "red sequence" composed of early-type galaxies exists in all environments at high luminosity, but it lacks of low luminosity (dwarf) galaxies in the lowest density environment. Conversely low luminosity isolated galaxies are predominantly of late-type. In other words the low luminosity end of the distribution is dominated by red dE galaxies in clusters and groups and by dwarf blue amorphous systems in the lowest density regions. At z=0 we find evidence for strong evolution induced by the environment (Nurture). Transformations take place mostly at low luminosity when star forming dwarf galaxies inhabiting low density environments migrate into amorphous passive dwarf ellipticals in their infall into denser regions. The mechanism involves suppression of the star formation due to gas stripping, without significant mass growth, as proposed by Boselli et al. (2008a). This process is more efficient and fast in ambients of increasing density. In the highest density environments (around clusters) the truncation of the star formation happens fast enough (few 100 Myr) to produce the signature of post-star-burst in galaxy spectra. PSB galaxies, that are in fact found significantly clustered around the largest dynamical units, represent the remnants of star forming isolated galaxies that had their star formation violently suppressed during their infall in clusters in the last 0.5-1.5 Gyrs, and the progenitors of future dEs.
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。
