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首页> 外文学位 >Probing the chemical composition of the Z 1 intergalactic medium with observations and simulations.
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Probing the chemical composition of the Z 1 intergalactic medium with observations and simulations.

机译：通过观察和模拟探索Z <1星系间介质的化学成分。

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摘要

Metals are produced in the stars in the galaxies, and a variety of feedback processes move metals from the sites of production into the intergalactic medium (IGM), enriching the material for future generations of stars. The signature of this process is etched in the recycled gas: its metallicity, elemental abundances, density, distribution, etc. The study of the low-redshift, z , IGM is the study of the last eight-billion years of cosmic chemical evolution and all prior enrichment.;In this thesis, I characterize the cosmic enrichment cycle with the use of observations and simulations. The gas is observed through quasar absorption-line spectroscopy. As the light of a distant quasar travels to us, intervening clouds of gas absorb the light at wavelengths characteristic, albeit redshifted, of the elements in the clouds. By identifying and modeling the elements associated with the absorption systems, I learn the ionic composition and density of the cosmic web (voids, filaments, and/or groups) along the line of sight.;From a detailed study of a single sightline, I observe a multi-phase IGM, with kinematically-distinct, hot and warm components (T ≈ 105.5 K and 104 K, respectively). By correlating the absorption systems with a complementary galaxy survey of the field around the background quasar, I find that the IGM systems arise in a variety of galactic environments. The metal-lines systems all have L > 0.1 L* galaxies within a few hundred kiloparsecs, which suggests this is the distance to which galactic feedback processes typically disperse metals.;I conduct a large, blind survey for triply-ionized carbon (C IV) absorption at z 1 in the spectra of 49 low-redshift quasars and compare their properties with those detected at z > 1. The mass density in C IV doublets with 13 ≤ log N(C+3) ≤ 15 at z 1 has increased by a factor of 2.8 +/- 0.7 over the error-weighted mean of the 1.5 z 5 measurements, where the mass density has not evolved significantly. The line density d NCIV /dX has not evolved as much, indicating that the average column density per doublet increases with decreasing redshift.;In addition, I compare the observed properties of C IV absorbers with those predicted by cosmological hydrodynamic simulations with a variety of physical models (e.g., feedback, cosmology). I also use the results from the simulations that reproduce well the observations to understand better the physical conditions giving rise to the C IV absorbing gas. The observations and simulations indicate that the log N(C+3) > 13 C IV absorption systems predominately come from circum-galactic (or halo) gas.
机译：金属是在银河系中的恒星中产生的，各种反馈过程将金属从生产场所转移到银河系中间介质（IGM）中，从而丰富了下一代恒星的物质。该过程的特征被蚀刻在再循环气体中：其金属性，元素丰度，密度，分布等。低红移z 0.1 L *个星系，这表明这是银河反馈过程通常分散金属的距离。我对三电离碳（C IV ）在49个低红移类星体的光谱中在z <1处的吸收，并将它们的性质与在z> 1处检测到的性质进行比较。C IV的质量密度在z <1时为13≤log N（C + 3）≤15相对于1.5 13 C IV吸收系统主要来自环银河（或卤素）气体。

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  • 作者

    Cooksey, Kathy L.;

  • 作者单位

    University of California, Santa Cruz.;

  • 授予单位 University of California, Santa Cruz.;
  • 学科 Physics Astronomy and Astrophysics.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 291 p.
  • 总页数 291
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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