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Simulations numeriques de modeles gaussiens et non-gaussiens de formation des galaxies

Abstract : I first model galaxy formation under the standard paradigm using constrained numerical simulations of the evolution of dark matter. I then falsify a competing scenario originally designed to favour an early epoch for galaxy formation. I analyze two large simulations of Cold Dark Matter cosmologies (LCDM and tCDM) with gaussian initial density fluctuations. The simulations mimic the Local Universe out to cz=8000 km/s. The galaxy populations are normalized with the local Tully-Fisher relation and the B-band luminosity function. Nearby massive clusters are reproduced in position and mass and some features of their brightest objects match the real cluster populations reasonably well. I then compare on larger scales the simulated distribution of galaxies to the PSCz and UZC catalogues : there is significant cross-correlation, proving the success of the whole set of numerical techniques, from the construction of the initial high-redshift density field to the semi-analytical model describing galaxy formation. Moreover, down to their luminosity resolution limit, the simulations show large voids which are completely bereft of DM halos or of any type of galaxies, in agreement with observations. At high redshift, the z=3 luminosity function is fainter than the data, but the models are still able to give qualitative insight into the properties and the spatial distribution of Lyman-Break galaxies, of QSO hosts, and of their descendants. As an alternative to the gaussian paradigm, I then consider the Isocurvature Cold Dark Matter (ICDM) model proposed by Peebles, where the initial DM density fluctuations are strongly positively skewed. I carry out two large simulations and verify simple z=0 analytical predictions. I find that the correlation lengths of massive clusters and the shape of the distribution of their peculiar velocities can falsify the model against the data. The ICDM model is also ruled out by recent measurements of the CMB anisotropies.
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https://tel.archives-ouvertes.fr/tel-00003239
Contributor : Hugues Mathis <>
Submitted on : Wednesday, August 6, 2003 - 6:30:17 PM
Last modification on : Monday, August 27, 2018 - 5:22:02 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 9:30:26 PM

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  • HAL Id : tel-00003239, version 1

Citation

Hugues Mathis. Simulations numeriques de modeles gaussiens et non-gaussiens de formation des galaxies. Astrophysique [astro-ph]. Université Paul Sabatier - Toulouse III, 2002. Français. ⟨tel-00003239⟩

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