AN INFRARED CUTOFF REVEALED BY THE 2 YEARS OF COBE OBSERVATIONS OF COSMIC TEMPERATURE-FLUCTUATIONS

We show that a good fitting to the first two years of observations by the Cosmic Background Explorer Differential Microwave Radiometers of t he two-point angular correlation function of cosmic background radiati on (CBR) temperature is given by models with a nonzero infrared cutoff k(min) in the spectrum of the primordial density perturbations. If th is cutoff comes from the finiteness of the universe, say, a topologica l T3 model, we find k(min) approximately (0.3 - 1.1)pi H-0/c with conf idence level 95%. Such a nonzero k(min) universe would also give a bet ter match to the observations both of the rms quadrupole anisotropy of CBR and of galaxy clustering.