LARGE-SCALE STRUCTURE IN ISOCURVATURE BARYON MODELS

Formation and evolution of large-scale structure in isocurvature baryon models are studied using cosmological N-body simulations. Our models assume spatially flat universes comprising baryon density parameter OMEGA(b) = 0.1-0.2 and the residual cosmological constant lambda = 1 - OMEGA(b). Then the results of the simulations mainly provide constraints on the spectral index n of the primordial density fluctuations. Both the spatial and the angular two-point correlation functions of galaxies are in good agreement with the observations for n = -1 models. Models with n = 0 lead to steeper correlation functions than the observations. In fact, n = -1 models produce reasonably the large-scale coherence in the peculiar velocity field as indicated by several observations. Together with the complementary constraints from the microwave background anisotropies, the acceptable parameter range of the isocurvature baryon models is severely restricted.