Constraints on reionization from CMB fluctuations.

The authors study the anisotropy of the cosmic microwave background (CMB) in mixed dark matter models, with non scale-invariant primordial power spectra (i.e. n {\ne 1) and a late, sudden reionization of the intergalactic medium at redshift z$_rh$. They test these models against recent detections of CMB anisotropy at large and intermediate angular scales. The likelihood analysis indicates that mixed dark matter models with blue power spectra (n \cong 1.24) and a reionization at z$_rh$ \equiv 20 are most consistent with the presently available CMB anisotropy data. }