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The large-scale temperature fluctuations of the cosmic microwave background (CMB) determined through the Sachs-Wolfe effect by scale-free, adiabatic, and Gaussian density inhomogeneities are discussed. The available observations on the large-scale temperature distribution are compared, taking into account the different experimental settings, and, also, the implications of a recently reported positive detection of CMB anisotropy on the density perturbations spectra index are discussed. 26 references.

On a calcule l'anisotropie a petite echelle dans des univers purement baryoniques, avec et sans constante cosmologique. Des modeles purement baryoniques ne sont pas compatibles avec les limites superieures actuelles de l'anisotropie meme si on a recours a une constante cosmologie Λ=1−Ω 0 . Toutefois, un modele domine par de la matiere froide, sombre, peut etre compatible avec les observations si Ω 0 h≥0,05 et Λ=1−Ω 0

The large-scale peculiar velocity field and the large- and intermediate-angular scale anisotropy of the cosmic microwave background are studied in inflationary cosmological models of critical density and containing primordial scale-invariant adiabatic density perturbations. Comparison with recent observations by de Vaucouleurs and Peters Provides tentative support for a cold dark matter scenario in which the dark matter is not appreciably less clustered than the luminous galaxy distribution.

On propose une simulation de l'evolution dynamique des amas de galaxies, utilisant un integrateur a N corps et en partant d'un large ensemble de conditions initiales statistiquement equivalentes