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首页> 外文学位 >Isolated early-type galaxies and the use of X-ray diagnostics to determine the evolution history of merging and merged systems.
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Isolated early-type galaxies and the use of X-ray diagnostics to determine the evolution history of merging and merged systems.

机译：孤立的早期星系和使用X射线诊断程序来确定合并和合并系统的演化历史。

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摘要

The dissertation presented details the search for isolated early-type galaxies (IEG). A strict set of isolation criteria were employed, requiring the candidate galaxy to be separated from nearest neighbors of MV ≤ --16.5 by a distance of 2.5 Mpc and a redshift-space separation of 350 km s-1. Such extreme isolation produces galaxies well suited as laboratories for the study of galaxy evolution, absent from the continual galaxy harassment observed for galaxies in group and cluster environments.;Global and surface photometry is used in verification of early-type morphology of the candidate galaxies. Two-dimensional residual maps, produced by model galaxy subtractions, are used to search for fine structure as well as isophotal deviations from a perfectly elliptical shape in the candidates. Clues provided by these analysis techniques are used to derive estimates of the past interaction history of the galaxies.;Also investigated was the viability of X-ray diagnostics to probe the evolutionary connection between compact groups, fossil groups (FG) and isolated ellipticals. Using the X-ray luminosity and gas temperatures, it was discovered that fossil groups are composed of two distinct populations. Population 1 FGs have X-ray characteristics similar to those of the compact groups and isolated ellipticals, while population 2 FGs are signicantly hotter and more luminous. The results suggest that compact groups are the predecessors of isolated ellipticals and population 1 FGs. Population 2 FGs appear to be the remnants of a collapsed poor cluster.;The highlights of the research are summarized as: 84% of the IEGs have blue colors and spectra indicative of young stellar populations and recent star formation. The conclusion is that the IEGs have continued to experience accretion of dwarf companions, which implies that even in extremely isolated galaxies, minor mergers strongly influence galaxy evolution. The faint nature of the IEGs, which are magnitudes fainter than previous isolated galaxy samples, imply that the IEGs are unlikely the remains of a collapsed group. Three sample galaxies are strong candidates for having a pristine nature and might serve as the near-zero interaction baseline necessary to separate the intrinsic galaxy properties and those properties induced by external interactions.
机译：论文详细介绍了寻找早期孤立星系（IEG）的方法。采用了严格的隔离标准集，要求将候选星系与MV≤--16.5的最近邻居隔开2.5 Mpc的距离和350 km s-1的红移空间。这种极端隔离产生的星系非常适合作为研究星系演化的实验室，而在群和星团环境中对星系的连续星系骚扰则没有这种星系。全球和表面光度法用于验证候选星系的早期形态。由模型星系减法生成的二维残差图用于搜索候选中的精细结构以及与理想椭圆形的等距偏差。这些分析技术提供的线索可用于得出银河系过去相互作用历史的估计值；此外，还研究了X射线诊断法探测紧密群，化石群（FG）和孤立的椭圆形之间的进化联系的可行性。使用X射线的光度和气体温度，发现化石群由两个不同的种群组成。群体1 FG的X射线特征类似于紧凑型群体和孤立的椭圆形，而群体2 FG则明显更热更发光。结果表明，紧致群是孤立椭圆和种群1 FG的前身。人口2 FG似乎是一个坍塌的贫民团的残余。该研究的重点总结为：84％的IEG具有蓝色和光谱，表明年轻的恒星种群和最近的恒星形成。结论是IEG持续经历着矮伴星的增加，这意味着即使在极端孤立的星系中，微小的合并也会强烈影响星系的演化。 IEG的微弱性质比以前的孤立星系样本微弱，这表明IEG不太可能是坍塌的星团的残骸。三个样本星系是具有原始性质的强候选者，并且可以用作分离固有星系性质和由外部相互作用诱导的那些性质所必需的接近零的相互作用基线。

著录项

  • 作者

    Fuse, Christopher Robert.;

  • 作者单位

    Texas Christian University.;

  • 授予单位 Texas Christian University.;
  • 学科 Physics Astronomy and Astrophysics.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 354 p.
  • 总页数 354
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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