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Title: Evolution of Galaxies and the intergalactic medium at high redshift
Researcher: Kulkarni, Girish
Guide(s): Bagla, J S
Keywords: galaxies
black holes
Upload Date: 17-Sep-2012
University: Homi Bhabha National Institute
Completed Date: July, 2011
Abstract: Research presented in this thesis follows two threads in the broad area of cosmology: (1) properties of the intergalactic medium (IGM), and (2) formation of galaxies and their evolution. Mainly from observations of absorption systems in high-redshift quasar spectra, the intergalactic medium has been inferred to be ionized, as well as chemically enriched, up to redshift of about six. This effect is termed reionization. It has been the focus of large amount of research in the last decade. With this in mind, this thesis deals with the following issues: (1) the problem of constraining early star formation from reionization-related observations; and (2) developing selfconsistent models of reionization and suggesting new observables. Apart from these two issue, we also look at galaxy formation in greater detail in this thesis. Understanding how observed small scale structure, including galaxies, can emerge in the well-accepted Cosmological Constant-Cold Dark Matter (LCDM) cosmological model is an important open problem. This thesis includes (1) predictions for the evolution of the neutral hydrogen content in galaxies and its large-scale distribution in the universe over a range of redshifts, and (2) a study of assembly of supermassive black holes in nuclei of high redshift galaxies. In the first component of this thesis, we use a simplified approach for studying formation of stars in collapsed haloes, and the resulting ionization and enrichment of the IGM. We consider a set of LCDM models allowed by observations and constrain parameters related to star formation with the help of the observed IGM metallicity and its Thomson scattering optical depth. We find that a ?normal? initial mass function (IMF) may satisfy these two constraints. Observations require a significant fraction of metals to escape from haloes to the IGM.
Pagination: xxiv, 195p.
Appears in Departments:Department of Physical Sciences

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01_title.pdfAttached File13.83 kBAdobe PDFView/Open
02_contents.pdf14.08 kBAdobe PDFView/Open
03_list of figures.pdf50.65 kBAdobe PDFView/Open
04_list of tables.pdf36.17 kBAdobe PDFView/Open
05_certificate.pdf6.19 kBAdobe PDFView/Open
06_declaration.pdf6.41 kBAdobe PDFView/Open
07_acknowledgements.pdf11.71 kBAdobe PDFView/Open
08_abstract.pdf77.61 kBAdobe PDFView/Open
09_chapter 1.pdf359.2 kBAdobe PDFView/Open
10_chapter 2.pdf366.17 kBAdobe PDFView/Open
11_chapter 3.pdf237.79 kBAdobe PDFView/Open
12_chapter 4.pdf927.99 kBAdobe PDFView/Open
13_chapter 5.pdf598.36 kBAdobe PDFView/Open
14_chapter 6.pdf1.01 MBAdobe PDFView/Open
15_bibliography.pdf60.19 kBAdobe PDFView/Open
16_synopsis.pdf67.06 kBAdobe PDFView/Open

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