Thesis (doctoral)--Stockholm University, 1983. / Includes bibliographical references.

Thesis (doctoral)--Katolicki Uniwersytet Lubelski. / On p. facing t.p.: Wydział Filozofii Chrześcijańskiej. Includes bibliographical references (p. 101-[109]).

Inaug.-Diss.--Erlangen. / Vita.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xviii, 319 p.; also includes graphics. Includes bibliographical references (p. 310-319). Available online via OhioLINK's ETD Center

Thesis (M. Div.)--St. Vladimir's Orthodox Theological Seminary, Crestwood, NY, 2007. / Abstract. Includes bibliographical references (leaves 42-43).

Made available in DSpace on 2016-05-17T16:50:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-09-14. Added 1 bitstream(s) on 2016-05-17T16:54:28Z : No. of bitstreams: 1 000855565.pdf: 2489794 bytes, checksum: c97ca8a54a4e48a751eda0262ecd418b (MD5) / O principal objetivo desta tese é explorar o papel das interações nucleares durante o universo primordial. Para tanto, importamos para a cosmologia um formalismo da mecânica estatística de equilíbrio baseado em sistemas interagentes relativísticos. A partir deste formalismo e utilizando uma abordagem fenomenológica das interações nucleares, construímos equações de estado cosmológicas constituídas de fótons, léptons e hádrons interagentes, e aplicamos estas equações no modelo padrão da cosmologia. Supondo certas extrapolações, as equações de estado propostas são capazes de gerar um regime de expansão acelerada primordial (inflação) conectado continuamente com a era da radiação existente durante a nuclessíntese. Este período inflacionário é suficientemente intenso para resolver os problemas de planura e horizonte, permitindo também uma explicação natural de porque o universo está se expandindo. Contudo, devemos ressaltar que todos esses resultados são obtidos apenas para um universo simétrico de matéria e antimatéria. Resumidamente falando, o trabalho realizado sugere que os processos de interação nuclear são importantes para a evolução do universo primordial podendo inclusive ser os responsáveis pelo período inflacionário. De uma perspectiva mais ampla, esta tese também tem por objetivo estabelecer um procedimento formal capaz de incluir termos de interação como fonte de gravitação na cosmologia. Este procedimento é baseado na teoria de ensembles da mecânica estatística, e em princípio pode ser aplicado sempre que o fluido cósmico estiver em equilíbrio termodinâmico / The main purpose of this thesis is to explore the role of the nuclear interactions during the early universe. For that, we import to cosmology an equilibrium statistical mechanics formalism based for relativistic interacting systems. Using this formalism and a phenomenological approach of the nuclear interactions, we built cosmological equations of state including photons, leptons and interacting hadrons and apply them to the cosmological standard model. Supposing certain extrapolations, the proposed equations of state are able to produce a primordial acceleration (inflation) continually linked with the radiation era present during the nucleosynthesis. This inflationary period is effective enough to solve the flatness and horizon problems, and it still allows a natural explanation for why the universe is expanding. However, we must stress that all these results are obtained only for a matter-antimatter symmetric universe. The research made suggest that the nuclear interactions are important for the early universe evolution and it might be the responsible for the inflationary period. This thesis has also the purpose of establishing a formal procedure able to include interaction terms as sources of gravitation in cosmology. This procedure is based in the ensemble theory of statistical mechanics, and can in principle be applied whenever the cosmic fluid is in thermodynamical equilibrium

Cosmology is now a precision science. The temperature anisotropies in the cosmic microwave background (CMB) have been exquisitely mapped by many experiments over the last decade. The Planck satellite was launched in 2009, observed the sky in temperature and polarisation, and released the nominal mission temperature data to the public in 2013. Planck has shed new light on CMB polarisation anisotropies and the polarisation signal from our own galaxy, and knowledge of the galactic emission forms a central part of this analysis presented in this thesis. I first introduce the background cosmology and review what we know about CMB temperature and polarisation anisotropies, including their mathematical formulation and representation on the sphere. I review our knowledge of the origin of galactic polarised foregrounds, particularly electron synchrotron and thermal dust emission. I then describe the generation of polarised CMB maps from an input cosmological model, and the generation of CMB polarised foregrounds using a variety of methods to create full-sky maps of the microwave sky at the Planck observing frequencies between 30 and 353 GHz. I develop a parametric fitting maximum-likelihood polarised component separation routine with correlated foreground parameters to extract the CMB and associated foregrounds to a high precision, and show that my method can reliably recover a primordial B-mode polarisation signal at r = 0.1 at multiple map resolutions. I then test the sky model against the full mission Planck data to examine how accurately the foregrounds are simulated, and find that along the galactic plane the simulations are accurate, but at high latitudes the agreement worsens. I also compare the polarisation morphology to that seen in the WMAP data and find a tension between Planck and WMAP. I present an analysis of the dx8 polarisation data in terms of polarised amplitudes and orientations, and investigate a variety of foreground separation routines to get a feel for the reliability of the data. Significant systematic issues are found and I conclude that in their current state, the polarisation data are not reliable enough for precise cosmology. Finally I develop a Fisher matrix analysis of the temperature power spectrum using the full mission covariance matrix to explore the parameter space around a CosmoMC simulation, and extract the principal components for different models. I use this to explore a strange oscillation in the power spectrum and conclude that it is a statistical fluke, a conclusion confirmed in a recent data release. I close by offering extensions to the work and a look into the future of the field.

Master of Science / Department of Physics / Lado Samushia / Part 1: The redshift-space bispectrum (three point statistics) of galaxies can be used to measure key cosmological parameters. In a homogeneous Universe, the bispectrum is a function of five variables and unlike its two point statistics counterpart -- the power spectrum, which is a function of only two variables -- is difficult to analyse unless the information is somehow reduced. The most commonly considered reduction schemes rely on computing angular integrals over possible orientations of the bispectrum triangle thus reducing it to sets of functions of only three variables describing the triangle shape. We use Fisher information formalism to study the information loss associated with this angular integration. We find that most of the information is in the azimuthal averages of the first three even multipoles. This suggests that the bispectrum of every configuration can be reduced to just three numbers (instead of a 2D function) without significant loss of cosmologically relevant information. Part 2: One way of enhancing the cosmological information extracted from the clustering of galaxies is by weighting the galaxy field. The most widely used weighting schemes assign weights to galaxies based on the average local density in the region and their bias with respect to the dark matter field. They are designed to minimize the fractional variance of the galaxy power-spectrum. We demonstrate that the currently used bias dependent weighting scheme can be further optimized for specific cosmological parameters. Part 3: Choice of the box-size of a cosmological simulation involves a crucial trade-off between accuracy and complexity. We use Lagrangian perturbation theory to study the effects of box size on the predicted power spectrum and Baryon Acoustic Oscillation ruler. We find that although the optimal size depends on the final redshift of evolution, in general, the 2-point statistics of relevant scales is fairly accurate for a simulation box-size of length greater than 1000 Mpc.

Orientador: Helio Vasconcelos Fagundes / Banca: German Gomero Ferrer / Banca: Armando Bernui Leo / Resumo: As flutuações da temperatura na Radiação Cósmica de Fundo em Universos com topologias multiplamentes conexas são estudadas. Encontram-se algumas restrições que caracterizam cada tipo de topologia, trazendo como consequência uma diferença entre as funções de correlação e espectros de potência para cada caso. Essas diferenças podem em princípio nos ajudar a diferenciar o tipo de topologia à qual pertencem / Abstract: Temperature fluctuations on the Cosmic Microwave Background in Universes with non-trivial topology are studied. We find some constraints that characterize each topology, which has as a consequence a difference between correlation functions and power spectra for each case. This can in principle help us to differentiate the type of topology to which they belong / Mestre

Orientador: Ruben Aldrovandi / Banca: Jose Geraldo Pereira / Banca: Mario Novello / Banca: Gilberto Medeiros Kremer / Banca: Amâncio Cesar Santos Friaça / Resumo: O principal objetivo desta tese é explorar o papel das interações nucleares durante o universo primordial. Para tanto, importamos para a cosmologia um formalismo da mecânica estatística de equilíbrio baseado em sistemas interagentes relativísticos. A partir deste formalismo e utilizando uma abordagem fenomenológica das interações nucleares, construímos equações de estado cosmológicas constituídas de fótons, léptons e hádrons interagentes, e aplicamos estas equações no modelo padrão da cosmologia. Supondo certas extrapolações, as equações de estado propostas são capazes de gerar um regime de expansão acelerada primordial (inflação) conectado continuamente com a era da radiação existente durante a nuclessíntese. Este período inflacionário é suficientemente intenso para resolver os problemas de planura e horizonte, permitindo também uma explicação natural de porque o universo está se expandindo. Contudo, devemos ressaltar que todos esses resultados são obtidos apenas para um universo simétrico de matéria e antimatéria. Resumidamente falando, o trabalho realizado sugere que os processos de interação nuclear são importantes para a evolução do universo primordial podendo inclusive ser os responsáveis pelo período inflacionário. De uma perspectiva mais ampla, esta tese também tem por objetivo estabelecer um procedimento formal capaz de incluir termos de interação como fonte de gravitação na cosmologia. Este procedimento é baseado na teoria de ensembles da mecânica estatística, e em princípio pode ser aplicado sempre que o fluido cósmico estiver em equilíbrio termodinâmico / Abstract: The main purpose of this thesis is to explore the role of the nuclear interactions during the early universe. For that, we import to cosmology an equilibrium statistical mechanics formalism based for relativistic interacting systems. Using this formalism and a phenomenological approach of the nuclear interactions, we built cosmological equations of state including photons, leptons and interacting hadrons and apply them to the cosmological standard model. Supposing certain extrapolations, the proposed equations of state are able to produce a primordial acceleration (inflation) continually linked with the radiation era present during the nucleosynthesis. This inflationary period is effective enough to solve the flatness and horizon problems, and it still allows a natural explanation for why the universe is expanding. However, we must stress that all these results are obtained only for a matter-antimatter symmetric universe. The research made suggest that the nuclear interactions are important for the early universe evolution and it might be the responsible for the inflationary period. This thesis has also the purpose of establishing a formal procedure able to include interaction terms as sources of gravitation in cosmology. This procedure is based in the ensemble theory of statistical mechanics, and can in principle be applied whenever the cosmic fluid is in thermodynamical equilibrium / Doutor