Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 10 of 10 for “"Lyman alpha forest"”.
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Cosmological hydrodynamic simulations of the Lyman-alpha forest
… of the formation and evolution of Ly$\alpha$ forest absorbers were performed in three CDM-like cosmological models: the standard CDM model (SCDM), the flat CDM model with a nonzero cosmological constant ($\Lambda$CDM) and the open CDM model (OCDM). Synthetic spectra along random …
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Measuring the Cosmological Constant Through the Lyman -Alpha Forest Using the Alcock -Paczynski Test
… in fundamental particle physics. The Lyalpha forest QSO spectra are observationally available from z ∼ 0 to z ∼ 4. Recently the concept of performing the Alcock-Paczynski test on the Lyalpha forest to determine the cosmological constant has been proposed. This motivates us to …
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Effect of magnetic seed fields on Lyman Alpha emission from distant quasars
… gas in the intergalactic medium which affect the Lyman-Alpha spectrum we observe. In this work we investigate to what extent the properties of the Lyman-Alpha forest are sensitive to the presence of large-scale cosmological magnetic fields as a function of the seed field intensity. To do so, we …
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QSO Absorption Lines
… epochs. This thesis describes a study of the Lyman alpha forest absorption systems seen in the spectra of high redshift QSOs. The Anglo-Australian Telescope has been used to obtain high resolution spectra of several bright QSOs. Considerable effort has gone into developing statistical …
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Computational Bayesian techniques applied to cosmology
… whilst cosmic microwave background radiation and Lyman-$\alpha$ forest constraints are less significant. Specific models with a conformal time symmetry in the Friedmann equation and with an additional dark energy component are tested and shown to be competitive to the vacuum dark energy model by …
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Jet Definitions in Effective Field Theory and Decaying Dark Matter
… and extended previous analyses to include Lyman-alpha forest, large scale structure, and weak lensing observations. Astrophysical constraints are not considered in this thesis. The bounds on the lifetime of decaying dark matter are dominated by either the late-time integrated Sachs-Wolfe …
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The formation of population III stars and their effect on cosmological structure in the early universe
… for the metals observed at low densities in the Lyman-Alpha forest."
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A detailed view of filaments and sheets of the warm-hot intergalactic medium
… hydrogen at temperatures of T ~ 10^4 K (the Lyman-alpha forest), at lower redshifts only about 20 % can be found in this state. The remain (about 50 to 70 % of the total baryons mass) is unaccounted for by observational means. Numerical simulations predict that these missing baryons could …
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Probing the Intergalactic Medium with high-redshift quasars
… estimated by measuring the mean flux in the Lyα forest, and scaling Γ_bkg in simulations such that the simulated mean flux matches the observed value. In Chapter 3 I investigate whether the precision of these estimates can be improved by using the entire flux probability distribution function …
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The transverse proximity effect in quasar spectra
… as a decreased level of absorption in the Lyman alpha forest of neutral hydrogen. This so-called proximity effect has been detected with high statistical significance towards luminous quasars. If quasars radiate rather isotropically, background quasar sightlines located near foreground …