MICROWAVE BACKGROUND-RADIATION ANISOTROPY FROM SCALAR FIELD GRADIENTS

Analytic calculations of the cosmological density fluctuations and mic rowave background radiation anisotropies induced by gradients in a top ologically trivial scalar field are presented. This anlaytic solution should provide a good test for numerical simulations of microwave anis otropy from scalar fields. To the extent that these results generalize to other scalar field models and configurations, they imply that (1) MBR measurements limit large-scale primordial variations greater than about 5 x 10(16) GeV within our horizon, (2) the total scalar field va riation is a fair predictor of the magnitude of the MBR anisotropy, bu t is only accurate to within a factor of about three, (3) scalar field s as well as other models of seeded perturbations produce a few times more anisotropy DELTAT/T for a given density fluctuation deltarho/rho (on the same scale) than do primordial adiabatic perturbations, (4) mo dels of scalar field seeds which produce a scale-invariant spectrum of perturbations seem to require galaxies to be more clustered than the mass on small scales, and (5) scalar fields do not ''tilt'' the Univer se.