Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Mathematics. / Microfiche copy available in Archives and Science. / Bibliography: leaves 203-204. / Ph.D.

In this thesis we make predictions of extreme elements of large-scale structure (LSS) in the universe. We base our study on the concordance cosmological model, the Lambda Cold-Dark-Matter (ΛCDM) model, and in doing so we utilise a suite of very large N-body,dark-matter-only simulations. To understand LSS throughout cosmic history, it is vital to quantify the evolution ofthe numbers of objects in the universe. To this end, we perform a numerical investigation into the abundance of dark matter haloes across an unprecedented combination of redshifts and masses. For the very young universe (z > 6), a fit is presented for the numbers of rare haloes that hosted the energetic objects that drove reionization. At lower redshifts we predict number counts of galaxy groups and clusters, the observation of which forms perhaps our current, best method of interpreting nature on large scales. Our low redshift results are based on simulations with very large volumes, which allows us to probe rare objects in a ΛCDM universe, including massive clusters, voids and extreme-velocity mergers. These objects challenge our understanding of the universe by exhibiting the extremes of the ΛCDM model. With the possible exception of the Bullet Cluster, our simulation results are in line with current observations. We study the late-time Integrated Sachs-Wolfe (ISW) effect using a (6 h−1Gpc)³ volume simulation which contains enough particles (6000³) to resolve luminous red galaxies. From these data we calculate the expected ISW-LSS cross-correlation signal in a ΛCDM universe. The signal is found to be strongest for LSS surveys that can probe redshift ranges of z ~ 0.2 to 0.8. The ISW effect promises to be an important measure of the evolution of dark energy, the overall understanding of which is perhaps the most important current goal in cosmology.

Thèse : Mécanique : Faculté des sciences de Paris : 1852. Thèse : Astronomie : Faculté des sciences de Paris : 1852. / Titre provenant de l'écran-titre.

Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Mathematical Sciences." Includes bibliographical references (p. 40).

Not available / text

Thesis (Ph. D.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: Neil J. Cornish. Includes bibliographical references (leaves 136-142).

Thesis (M.Sc.)--York University, 2004. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 126-129). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: LINK NOT YET AVAILABLE.

Thesis (M.S.)--Baylor University, 2006. / Includes bibliographical references (p. 74-76).

Orientador: Tadashi Yokoyama / Banca: Othon Cabo Winter / Banca: Marcos Tadeu dos Santos / Resumo: É quase um consenso que os planetas ao serem formados, nasceram com obliquidades quase nulas. No entanto, para os planetas gigantes, exceto Júpiter, as atuais obliquidades estão longe de zero. Para Saturno, Urano e Netuno elas são, respectivamente, 25,61°, 97,86°, 28,31°. Em geral, as razões que alteraram as obliquidades estão associadas a efeitos gravitacionais como colisões ou capturas em ressonâncias. Neste trabalho pretendemos montar o sistema médio que governa a dinâmica de longo período da variação da obliquidade de um planeta considerando o Sol e um satélite com massas e distâncias diversas. Usaremos variáveis de Andoyer pois, por serem canônicas, as médias podem ser realizadas de forma rigorosa sempre que feitas em variáveis ação - ângulo. A questão do "wooble" pode ser facilmente incorporada se necessário. Pretendemos com este modelo estudar a variação da obliquidade de Netuno, mas em princípio pode ser usado também nos casos de exoplanetas (ARMSTRONG et al., 2014). O planeta Netuno, aparentemente é o único que não tem nenhum satélite regular primordial, ao contrário dos demais. Boué e Laskar (2010) fizeram uso de um satélite adicional para explicar a obliquidade de Urano. Porém, a presença de um satélite adicional de massa muito elevada, poderia desestabilizar os primordiais já existentes. No caso de Netuno, as massas dos satélites adicionais que pretendemos usar podem ser muito menores do que aquelas usadas por Boué e Laskar, o que elimina de vez, possível desestab... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: It is almost a consensus that the planets, when formed, were born with almost zero obliquities. However, for giant planets except Jupiter, the current obliquities ( ) are far from zero. For Saturn, Uranus, and Neptune they are, respectively, 25 . 6 ◦, 97 . 8 ◦, 28 . 3 ◦ . In general, the reasons that changed the obliquities are associated to gravitational effects such as collisions or captures in resonances. In this work we intend to build the average system that governs the long period dynamics of the variation of the obliquity of a planet considering the Sun and a satellite with different masses and distances. We will use Andoyer variables, because they are canonical, so averages can be performed rigorously whenever they are made in angle-action variables. The "wooble" issue can be easily incorporated if necessary. We intend with this model to study the variation of the Neptune's obliquity, but in principle it can also be used in the case of exoplanets (ARMSTRONG et al., 2014). The planet Neptune, apparently is the only one that has no regular primordial satellite, unlike the others. Boué e Laskar (2010), used an additional satellite to explain the Uranus' obliquity. However, the presence of an additional satellite with very high mass could destabilize the existing primordial ones. In the case of Neptune, the masses of the additional satellites that we intend to use may be much smaller than those used by Boué and Laskar, which eliminates possible destabilization of even... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:25:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-10-27Bitstream added on 2014-06-13T19:47:34Z : No. of bitstreams: 1 machuca_jfl_me_guara.pdf: 8805916 bytes, checksum: a079609323009e7947c11ada2408948e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Asteroides de alta inclinação são objetos com sin(i) > 0.3. Entre estes asteroides podemos distinguir objetos com inclinação menor que o centro da ressonância secular ν6 = g−g6 e objetos com inclinação superior. Os atuais mecanismos de mobilidade dinâmica não podem aumentar facilmente inclinações menores do que do centro da ressonância ν6. A presença de objetos de alta inclinação pode, portanto, estar relacionada com fases iniciais do Sistema Solar. Neste trabalho obtemos elementos próprios sintéticos para a região da família de Pallas, encontramos grupos dinâmicos e determinamos a significância estatística destes grupos. Estudamos a evolução dinâmica devida a perturbações planetárias e efeitos não gravitacionais das famílias e clumps identificados na região das famílias de Pallas e Hansa (Carruba 2010b). Estudamos regiões dinamicamente estáveis, que são surpreendentemente caracterizadas por um número muito baixo de asteroides, contrariamente a objetos de baixa inclinação que ocupam tudo a região dinamicamente viável. Identificamos duas areas caracterizadas por tempos de permanência de 100 milhões de anos o mais, quando a força Yarkovsky é considerada, com baixa densidade de asteroides. Obtemos elementos próprios sintéticos para 10865 objetos na região da família de Euphrosyne e identificamos famílias e clumps no domínio dos elementos próprios e frequências. Com relação a outros trabalhos sobre identificação de famílias na área, aqui nos investigamos o efeito que a rede local de ressonâncias seculares tem sobre a evolução dinâmica das famílias e clumps. Identificamos por primeira vez, novas populações de objetos em estados ressoantes de libração anti-alinhada de ν6 e anti-alinhada e alinhada de ν5. / Highly inclined asteroids are objects with sin(i) > 0.3. Among these asteroids we can distinguish between objects with inclinations lower than the center of the secular resonance ν6 = g−g6 and objects with higher inclinations. The current mechanisms of dynamical mobility cannot easily increase inclinations to value higher than that of the center of the ν6 resonance. The presence of high inclination objects may therefore be related to early stages of the Solar System. In this work we obtained synthetic proper elements for the region of the Pallas family, we found dynamical groups and determined the statistical significance of these groups. We studied the dynamic the dynamical evolution caused by planetary perturbations and non-gravitational effects of the families and clumps identified in the region of the Pallas and Hansa families (Carruba 2010b). We studied regions dynamically stable that on surprisingly characterized by a low number of asteroids, contrary to objects of lower inclinations that tend to occupy all the viable stable regions. We identified two areas characterized by permanence time of 100 Myr or more when the Yarkovsky force is considered, but with a small number density of bodies. We obtained synthetic proper elements for 10865 objects in the region of the Euphrosyne families and identify families and clumps in the domain of proper elements and frequencies. With respect to other work on family identification in the area, here we investigated the role that the local web of secular resonances has had on the dynamical evolution of families and clumps. We identify for the first time, new populations of objects inν6 anti-aligned libration and ν5 anti-aligned and aligned resonant states.