Yeung, Shek = 暗能量和暗物質模型課題 / 楊碩. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 88-91). / Abstracts in English and Chinese. / Yeung, Shek = An neng liang he an wu zhi mo xing ke ti / Yang Shuo. / Chapter 1 --- Overview of Cosmology --- p.1 / Chapter 1.1 --- The Friedmann-Robertson-Walker Metric and the Friedmann Equations --- p.1 / Chapter 1.2 --- The Hubble constant and the Expansion of the Universe --- p.3 / Chapter 1.3 --- The Energy Contents in the Universe --- p.4 / Chapter 1.4 --- Cosmological Observations --- p.8 / Chapter 2 --- Review of CMB Physics --- p.13 / Chapter 2.1 --- The Anisotropy Spectrum --- p.13 / Chapter 2.2 --- The Boltzmann Equations and Einstein Field Equation --- p.15 / Chapter 2.3 --- Initial Conditions --- p.18 / Chapter 2.4 --- Inhomogeneities of Matters --- p.21 / Chapter 2.5 --- Inhomogeneities and Anisotropies of Photons --- p.23 / Chapter 2.5.1 --- Tightly Coupled Limit of the Boltzmann equations --- p.23 / Chapter 2.5.2 --- Diffusion Damping --- p.25 / Chapter 2.5.3 --- Free Streaming --- p.25 / Chapter 2.5.4 --- Cosmological Parameters --- p.26 / Chapter 3 --- Extra Dimension Model with Casimir Effect --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Extra Dimension Model --- p.29 / Chapter 3.3 --- The Casimir Effect --- p.34 / Chapter 3.4 --- Results and Conclusion --- p.40 / Chapter 4 --- Decaying Sterile Neutrino Model --- p.44 / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- The Model --- p.46 / Chapter 4.3 --- Results and Conclusion --- p.61 / Chapter 5 --- Summary of the Thesis --- p.86 / Bibliography --- p.88

Chan, Wing Hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 76-78). / Abstracts in English and Chinese. / Chan, Wing Hang. / Chapter 1 --- Review of Cosmology --- p.1 / Chapter 1.1 --- Background Evolution of Universe --- p.1 / Chapter 1.1.1 --- The Cosmological Principle --- p.1 / Chapter 1.1.2 --- The Non-static Universe --- p.3 / Chapter 1.1.3 --- Robertson-Walker metric --- p.3 / Chapter 1.1.4 --- Scale Factor and Cosmological Redshift --- p.3 / Chapter 1.1.5 --- Hubble Constant --- p.4 / Chapter 1.1.6 --- The Einstein Field Equations --- p.4 / Chapter 1.1.7 --- The Cosmological Constant --- p.6 / Chapter 1.1.8 --- Time Evolution --- p.6 / Chapter 1.1.9 --- Continuity Equation --- p.7 / Chapter 1.1.10 --- Conformal Distance --- p.8 / Chapter 1.2 --- Observational Data --- p.8 / Chapter 1.2.1 --- Type Ia Supernovae --- p.9 / Chapter 1.2.2 --- Cosmic Microwave Background --- p.9 / Chapter 2 --- Review of Dark Energy Models --- p.11 / Chapter 2.1 --- The Cosmological Constant --- p.11 / Chapter 2.2 --- Quintessence --- p.11 / Chapter 2.3 --- Extra Dimension Models --- p.12 / Chapter 2.3.1 --- Kaluza-Klein --- p.12 / Chapter 2.3.2 --- Generalized Homogeneous and Isotropic Extra Dimensions --- p.12 / Chapter 3 --- Review of CMB and Type Ia Supernovae --- p.17 / Chapter 3.1 --- Type Ia Supernovae --- p.17 / Chapter 3.1.1 --- Comparison of cosmological models with recent SNIa data --- p.18 / Chapter 3.2 --- Cosmic Microwave Background Radiation --- p.18 / Chapter 3.2.1 --- Power Spectrum of CMBA --- p.18 / Chapter 3.2.2 --- Photon Baryon Oscillation --- p.21 / Chapter 3.2.3 --- Acoustic Peaks --- p.23 / Chapter 3.2.4 --- Matter Perturbation --- p.24 / Chapter 3.2.5 --- Baryon Loading --- p.24 / Chapter 3.2.6 --- Photons Driving --- p.25 / Chapter 3.2.7 --- Initial Conditions --- p.25 / Chapter 3.2.8 --- Reionization --- p.26 / Chapter 3.2.9 --- The Vanilla ACDM Model --- p.26 / Chapter 3.2.10 --- Summary of CMBA --- p.26 / Chapter 4 --- Constraining Dark Energy Models --- p.27 / Chapter 4.1 --- Constraining Dark Energy Density Using SN Ia data --- p.27 / Chapter 4.1.1 --- Direct Calculation of Dark Energy Density --- p.27 / Chapter 4.2 --- Constraining Dark Energy Density Using CMB data --- p.31 / Chapter 4.2.1 --- Dark Energy Evolution for time varying EOS --- p.31 / Chapter 4.2.2 --- Dark Energy Density Perturbation --- p.32 / Chapter 4.2.3 --- Parameterization of Time Varying Dark Energy --- p.32 / Chapter 4.2.4 --- Effect of Dark Energy Density on CMBA power spectrum --- p.33 / Chapter 4.2.5 --- Limitations and Difficulties Constraining Dark Energy Equation of State --- p.41 / Chapter 4.2.6 --- Constraining the Evolution of Dark Energy Density with a polynomial model --- p.54 / Chapter 4.2.7 --- Constraining Evolution of Dark Energy Density with Gaussian-type EOS --- p.59 / Chapter 4.2.8 --- Constraining Evolution of Dark Energy Step Function EOS with CMB Acoustic Peaks --- p.66 / Chapter 5 --- Summary --- p.73 / Bibliography --- p.76

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, December 2003. / Includes bibliographical references. Also available on the Internet.

The object of this thesis is to present various applications of the theory of cosmological perturbations. Within are contained a number of manuscripts, each concerned with a separate aspect of the theory. The thesis itself begins with a general overview of cosmological perturbation theory designed to be accessible to the non-specialist. Both the classical and quantum first order theory are considered. Back-reaction, via the formalism of the Effective Energy Momentum Tensor (EEMT) is reviewed. Subsequent chapters are more specialized dealing with various applications of the theory. At first order, topics discussed include the classicalization of cosmological perturbations (chapter 2), and the effects of including the dilaton and its fluctuations on a novel mechanism for the production of inhomogeneities in string gas cosmology (chapter 3). At second order, an original solution to the Dark Energy problem is proposed (chapter 4), and the effects of back-reaction on the power spectrum, including the spectral index and the gaussianity, are examined (chapter 5).

Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: David Lowe. Includes bibliographical references (leaves 111-122). Also available online.

Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 75-80). Also available for download via the World Wide Web; free to University of Oregon users.

Made available in DSpace on 2016-05-17T16:51:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-19. Added 1 bitstream(s) on 2016-05-17T16:54:21Z : No. of bitstreams: 1 000855561.pdf: 728928 bytes, checksum: d9c47745ba9f0ff381d16d64c98da423 (MD5) / Investigamos a formação, em larga escala, de estruturas no Universo, na presença da energia escura. Sua influência sobre o crescimento de perturbações cosmológicas é exercida tanto através do efeito sobre a taxa de expansão do fundo cósmico homogêneo, quanto de suas próprias flutuações de densidade de energia. Para calcularmos a taxa de formação de aglomerados de galáxias, empregamos uma generalização do formalismo de colapso esférico para a inclusão de fluidos com pressão. Um importante efeito de flutuações de energia escura associados a halos de matéria escura é a indução de halos de energia escura, que reprimem o crescimento de estruturas quando temos equações de estado não phantom; por outro lado, quando temos equações de estado phantom, são gerados vazios de energia escura, aumentando o crescimento de estruturas de matéria. Outro importante efeito ocorre quando consideramos a possibilidade da energia escura mudar sua equação de estado quando há grandes variações de sua densidade no interior dos halos em relação ao fundo homogêneo. O grande número de parametrizações da energia escura que foram obtidos com dados, de supernovas Ia são sensíveis apenas até desvios para o vermelho de ordem um. Mostramos que as parametrizações produzem assinaturas distintas na formação de aglomerados com o uso do formalismo de Press-Schechter. Portanto, futuras observações de aglomerados galácticos podem prover vínculos importantes no comportamento da energia escura durante a evolução do Universo / We investigate large scale structure formation in universe with dark energy presence. The dark energy influence on cosmological perturbation growth is exerted both through its effect on the expansion rate of background, and through its own density fluctuation as well. To compute the rate of formation of massive objects we employed the spherical collapse formalism, which was generalized to include fluids with pressure. An important effect caused by fluctuations in dark energy associated with dark matter halos is the induction of dark energy halos damping the growth of structures when the equations of state are non-phantom; on the other hand, phantom models generate dark energy voids, enhancing the growth of matter halos. Other important effect occurs when we consider the possibility of dark energy changing its equation of state when there are large differences between densities in the background and in the halos. The large number of dark energy parametrizations obtained with supernova Ia data are only sensitive to redshifts up to order one. We show these parametrizations produce distinguishable signatures in cluster formation using the Press-Schechter formalism. Therefore, future observations of galaxy clusters can provide important constraints on the behavior of dark energy in the course of universe evolution

Orientador: Rogério Rosenfeld / Banca: Ruben Aldrovandi / Banca: Luís Raul Weber Abramo / Resumo: Nos últimos anos diversas evidências acumularam-se indicando que o universo é plano e dominado por alguma forma de energia escura, cuja pressão negativa está atualmente fazendo com que ele esteja em expansão acelerada. Vários modelos têm sido propostos para a energia escura, entre os quais destacam-se os modelos de quintessência, nos quais essa energia é modelada por um campo escalar. Neste trabalho analisamos alguns vínculos observacionais nos modelos de quintessência com potenciais exponenciais, e obtivemos limites para o espaço de parâmetros desses modelos no caso em que a quintessência está desacoplada dos demais componentes do universo e no caso em que ela está acoplada à partícula de matéria escura. No caso desacoplado, estudamos as soluções do tipo scaling, e mostramos que nesse regime, o único em que a quintessência exponencial desacoplada apresenta soluções cosmologicamente realísticas, esses modelos não podem ser considerados menos naturais que os demais potenciais de quintessência. Obtivemos ainda que o caso acoplado, assim como o desacoplado, também não resolve o problema da coincidência cósmica, e que a idade do universo nestes modelos é consideravelmente maior que no caso desacoplado, de modo que os limites na idade podem ser úteis para distinguir observacionalmente entre as quintessências acoplada e desacoplada / Abstract: During the last years many evidences are indicating that the universe is flat and dominated by some form of dark energy, whose negative pressure is currently driving its accelerated expansion. A plenty of models have been proposed, with special attention to the quintessence models, in which the dark energy is modelled by a scalar field. In this work we have analysed some observational constraints in the quintessence models with exponential potentials, and we have put limits on the parameter space in both coupled and uncoupled cases. In the uncoupled case, we have studied the scaling Solutions, and we have showed that in this regime, that is the only one in which the exponential uncoupled quintessence presents realistic Solutions, such models can not be considered less natural than others quintessence potentials. We have also obtained that in the case in which the quintessence is coupled to dark matter the cosmic coincidence problem can not be solved, and that the age for coupled models is considerably higher than the age for non-coupled models, in such a way that limits on the age can be useful in distinguishing between coupled and non-coupled models. / Mestre

Orientador: Rogério Rosenfeld / Banca: Reuven Opher / Banca: Ioav Waga / Banca: Ruben Aldrovandi / Banca: José Ademir Sales de Lima / Resumo: Investigamos a formação, em larga escala, de estruturas no Universo, na presença da energia escura. Sua influência sobre o crescimento de perturbações cosmológicas é exercida tanto através do efeito sobre a taxa de expansão do fundo cósmico homogêneo, quanto de suas próprias flutuações de densidade de energia. Para calcularmos a taxa de formação de aglomerados de galáxias, empregamos uma generalização do formalismo de colapso esférico para a inclusão de fluidos com pressão. Um importante efeito de flutuações de energia escura associados a halos de matéria escura é a indução de halos de energia escura, que reprimem o crescimento de estruturas quando temos equações de estado não phantom; por outro lado, quando temos equações de estado phantom, são gerados vazios de energia escura, aumentando o crescimento de estruturas de matéria. Outro importante efeito ocorre quando consideramos a possibilidade da energia escura mudar sua equação de estado quando há grandes variações de sua densidade no interior dos halos em relação ao fundo homogêneo. O grande número de parametrizações da energia escura que foram obtidos com dados, de supernovas Ia são sensíveis apenas até desvios para o vermelho de ordem um. Mostramos que as parametrizações produzem assinaturas distintas na formação de aglomerados com o uso do formalismo de Press-Schechter. Portanto, futuras observações de aglomerados galácticos podem prover vínculos importantes no comportamento da energia escura durante a evolução do Universo / Abstract: We investigate large scale structure formation in universe with dark energy presence. The dark energy influence on cosmological perturbation growth is exerted both through its effect on the expansion rate of background, and through its own density fluctuation as well. To compute the rate of formation of massive objects we employed the spherical collapse formalism, which was generalized to include fluids with pressure. An important effect caused by fluctuations in dark energy associated with dark matter halos is the induction of dark energy halos damping the growth of structures when the equations of state are non-phantom; on the other hand, phantom models generate dark energy voids, enhancing the growth of matter halos. Other important effect occurs when we consider the possibility of dark energy changing its equation of state when there are large differences between densities in the background and in the halos. The large number of dark energy parametrizations obtained with supernova Ia data are only sensitive to redshifts up to order one. We show these parametrizations produce distinguishable signatures in cluster formation using the Press-Schechter formalism. Therefore, future observations of galaxy clusters can provide important constraints on the behavior of dark energy in the course of universe evolution / Doutor

No description available.