Collapse of Primordial Clouds

We present here studies of collapse of purely baryonic Population III objects with masses ranging from $10M_\odot$ to $10^6M_\odot$. A spherical Lagrangian hydrodynamic code has been written to study the formation and evolution of the primordial clouds, from the beginning of the recombination era ($z_{rec} \sim 1500$) until the redshift when the collapse occurs. All the relevant processes are included in the calculations, as well as, the expansion of the Universe. As initial condition we take different values for the Hubble constant and for the baryonic density parameter (considering however a purely baryonic Universe), as well as different density perturbation spectra, in order to see their influence on the behavior of the Population III objects evolution. We find, for example, that the first mass that collapses is $8.5\times10^4M_\odot$ for $h=1$, $\Omega=0.1$ and $\delta_i={\delta\rho / \rho}=(M / M_o)^{-1/3}(1+z_{rec})^{-1}$ with the mass scale $M_o=10^{15}M_\odot$. For $M_o=4\times10^{17}M_\odot$ we obtain $4.4\times10^{4}M_\odot$ for the first mass that collapses. The cooling-heating and photon drag processes have a key role in the collapse of the clouds and in their thermal history. Our results show, for example, that when we disregard the Compton cooling-heating, the collapse of the objects with masses $>8.5\times10^4M_\odot$ occurs earlier. On the other hand, disregarding the photon drag process, the collapse occurs at a higher redshift.Comment: 10 pages, MN plain TeX macros v1.6 file, 9 PS figures. Also available at http://www.iagusp.usp.br/~oswaldo (click "OPTIONS" and then "ARTICLES"). MNRAS in pres

Collapse of Primordial Clouds II. The Role of Dark Matter

In this article we extend the study performed in our previous article on the collapse of primordial objects. We here analyze the behavior of the physical parameters for clouds ranging from $10^7M_\odot$ to $10^{15}M_\odot$. We studied the dynamical evolution of these clouds in two ways: purely baryonic clouds and clouds with non-baryonic dark matter included. We start the calculations at the beginning of the recombination era, following the evolution of the structure until the collapse (that we defined as the time when the density contrast of the baryonic matter is greater than $10^4$). We analyze the behavior of the several physical parameters of the clouds (as, e.g., the density contrast and the velocities of the baryonic matter and the dark matter) as a function of time and radial position in the cloud. In this study all physical processes that are relevant to the dynamical evolution of the primordial clouds, as for example photon-drag (due to the cosmic background radiation), hydrogen molecular production, besides the expansion of the Universe, are included in the calculations. In particular we find that the clouds, with dark matter, collapse at higher redshift when we compare the results with the purely baryonic models. As a general result we find that the distribution of the non-baryonic dark matter is more concentrated than the baryonic one. It is important to stress that we do not take into account the putative virialization of the non-baryonic dark matter, we just follow the time and spatial evolution of the cloud solving its hydrodynamical equations. We studied also the role of the cooling-heating processes in the purely baryonic clouds.Comment: 8 pages, MN plain TeX macros v1.6 file, 13 PS figures. Also available at http://www.iagusp.usp.br/~oswaldo (click "OPTIONS" and then "ARTICLES"). MNRAS in pres

Suinocultura e meio ambiente em Santa Catarina: indicadores de desempenho e avaliação sócio-econômica.

bitstream/item/58223/1/doc120.pdfProjeto/Plano de Ação: 16.00.30004-0

Utilização de técnicas de segmentação e classificação de imagens LANDSAT-TM para o mapeamento do uso das terras na região de Campinas.

Os produtos do sensoriamento remoto tem sido, nas últimas décadas, a ferramenta mais utilizada e testada nos mapeamentos da cobertura terrestre. O desenvolvimento de novas máquinas e programas para auxiliar a interpretação de imagens de satélite, tem possibilitado a integração cada vez maior destas ferramentas. Este trabalho testou e discutiu o potencial e limitações do algoritmo de segmentação por crescimento de regiões, para o mapeamento da ocupação e uso das terras, em áreas heterogêneas e densamente ocupadas, utilizando imagens do satélite Landsat-TM, na escala 1:50.000. Através da segmentação de uma imagem Landsat-TM e da classificação supervisionada dos polígonos definidos pelo sistema, foi elaborado um mapa de uso e ocupação das terras, testado através da execução de levantamento de campo, em 88 dos 388 polígonos formados no processo. Este trabalho envolveu ainda uma etapa de tratamento numérico dos dados, visando quantificar a precisão do mapeamento efetuado e discutir os problemas encontrados nas rotinas de segmentação e classificação

Avaliação do termo de ajustamento de conduta da suinocultura amauc/consórcio lambari através de indicadores sociais, econômicos e ambientais.

Projeto: 03.06.05.020

Ascensão e queda nos preços do milho.

bitstream/item/142482/1/Ascencao-queda.pdfIndicadores de tendência

Grandes esperanças.

bitstream/item/142507/1/Grandes-esperancas.pd

Produção animal e meio ambiente: o caso TAC da suinocultura em Santa Catarina.

Projeto/Plano de Ação: 03.06.05.020