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|a Kohler, Katharina.
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|a Studying the epoch of reionization with synthetic spectra from large-scale simulations
|h [electronic resource]
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|c 2006.
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|a 143 pages.
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|a text
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|a Source: Dissertation Abstracts International, Volume: 67-05, Section: B, page: 2605.
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|a Adviser: Andrew J. S. Hamilton.
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|b Ph.D.
|c University of Colorado at Boulder
|d 2006.
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| 520 |
3 |
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|a This thesis focuses on three aspects of current cosmological problems related to the epoch of reionization. The first aspect concerns the nature and the physical properties of Lyman-limit systems and their surroundings observed in absorption against high redshift quasars. Analysis of simulations of the universe at z = 4 with box sizes 4 and 8h-1 Mpc reveals that the Lyman-limit systems are bound to or in orbit around galaxies of a large range of masses. They do not appear to be highly neutral self-shielded clumps of gas in dark matter "minihalos", but ionized clouds of gas from galaxy formation.
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|a The second main part of the thesis focuses on a method developed to increase the size of cosmological simulations using clumping factors. This approach allows for a large enough simulation volume to include rare luminous quasars while at the same time still accounting for the important physical processes on small scales. The clumping factor formalism is then used to investigate the epoch of reionization around z = 6 by creating synthetic quasar spectra to compare to observations by the Sloan Digital Sky Survey (SDSS). The simulations are fitted to the mean transmitted Lyman-alpha flux observed by SDSS. The analysis of the lines of sight shows that most HII regions are not spherical and their size depends on the quasar lifetime.
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|a The third part of the thesis explores another application of the large-scale simulation developed in the previous part to the redshift range z = 7 to z = 10. I developed synthetic spectra for the 21cm line to probe the lines of sight for signatures of HII regions at high redshift. This project showed that one can expect to find evidence of very distant quasars with the next generation radio telescopes.
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|a School code: 0051.
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|a Theses
|x CU Boulder
|x Astrophysical, Planetary, and Atmospheric Sciences.
|2 local.
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|a Hamilton, Andrew J. S.,
|e advisor.
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|t Dissertation Abstracts International
|g 67-05B.
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|u https://colorado.idm.oclc.org/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219034
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