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Cosmology past and ongoing projects in Toru˝ - brief summary for main page

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Shape of the Universe

RBSG08 image metric parameters image Scientific models of the Universe are intended to satisfy the Einstein field equations, that roughly speaking, state that curvature = density. The models allow many different sorts of spaces, which have the local property called a metric (a sort of rule for locally measuring distances, that determines curvature) and have global properties that define them, such as topology. Together curvature and topology can be described as shape. The metric of our Universe model has many parameters such as the Hubble parameter, the baryon density parameter, the baryonic and non-baryonic dark matter density parameter \Omega_m, and the dark energy parameter \Omega_\Lambda.

Density fluctuations

The Universe is not perfectly the same everywhere in space - even when the Universe was just a few hundred thousand years old, some regions were more dense and some were less dense. The more dense regions eventually collapsed under their own weight, via gravity, and formed galaxies, stars, and planets. Can a theory of inflation explain the origin of these density fluctuations? There are some observational hints that this might be the case. One of the research strategies for selecting an inflationary theory out of the many available scenarios is to check for non-Gaussian statistical properties of the fluctuations. These fluctuations are not just interesting for galaxy formation, they are also useful for measuring the curvature of space.

Collapsed objects

Density fluctuations on the smaller scales (up to about 1 Mpc, a few million light-years) collapsed gravitationally, forming galaxy clusters and galaxies in which stars and planets formed. Comparing observations of galaxies and galaxy clusters to the cosmic microwave background and separating the two effects is a major theme of the observational aspects of the OCRA program using our 32m radio telescope.


See also CosmoProjectsOld
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I Attachment Action Size Date Who Comment
metric_par.jpgjpg metric_par.jpg manage 55.8 K 14 Jul 2010 - 02:03 BoudRoukema ArXiv:0106135
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Topic revision: r4 - 14 Aug 2012, BoudRoukema
 
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