Abstract
In the gauge-invariant formalism, the evolution of adiabatic and baryonic isocurvature density perturbations in a universe dominated by cold dark matter (CDM) is throughly investigated. We evaluate anisotropies in the cosmic microwave background (CMB) and large scale peculiar velocities. From the recent observations of CMB fluctuations, we find new and stringent constraint is obtained for adiabatic CDM models as Ω0h-1 > 0.3. As for baryonic isocurvature perturbations, though the constraint is required as Ω0h-1 ≳0.6, we find these baryonic isocurvature models are more viable than axion isocurvature models. However it is difficult for both adiabatic and baryonic isocurvature CDM models to explain the observed large scale velocity field at ≳50 h-1 Mpc while being consistent with the observations of CMB anisotropies.

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