An Isocurvature Cold Dark Matter Cosmogony. II. Observational Tests

A companion paper presents a worked model for evolution through inflation to initial conditions for an isocurvature model for structure formation. It is shown here that the model is consistent with available observational constraints that can be applied without the help of numerical simulations. The model gives a generally good fit to the distributions of the thermal cosmic background radiation and the galaxies, with the possible need for a special adjustment to fit the COBE measurement of the slope of the fluctuation spectrum on large angular scales. The mass function for clusters of galaxies requires a rather low but observationally acceptable mass density, 0.1<~Ω<~0.2 in a cosmologically flat universe. Galaxies would be assembled earlier in this model than in the adiabatic version, an arguably good thing. Aspects of the predicted non-Gaussian character of the anisotropy of the thermal background radiation in this model are discussed.