An infrared cutoff revealed by the two years of COBE observations of cosmic temperature fluctuations.

Abstract

We show that a good fitting to the first two years of observations by the Cosmic Background Explorer Differential Microwave Radiometers of the two-point angular correlation function of cosmic background radiation (CBR) temperature is given by models with a nonzero infrared cutoff ${k}_{min}$ in the spectrum of the primordial density perturbations. If this cutoff comes from the finiteness of the universe, say, a topological T3 model, we find ${k}_{min}\ensuremath{\sim}(0.3\ensuremath{-}1.1)\ensuremath{\pi}\frac{{\mathrm{H}}_{0}}{c}$ with confidence level 95%. Such a nonzero ${k}_{min}$ universe would also give a better match to the observations both of the rms quadrupole anisotropy of CBR and of galaxy clustering.