COSMIC MICROWAVE BACKGROUND OBSERVATIONS - IMPLICATIONS FOR HUBBLES CONSTANT AND THE SPECTRAL PARAMETER-N AND PARAMETER-Q IN COLD DARK-MATTER CRITICAL DENSITY UNIVERSES

Recent cosmic microwave background (CMB) measurements over a large ran ge of angular scales have become sensitive enough to provide interesti ng constraints on cosmological parameters within a restricted class of models. We use the CMB measurements to study inflation-based, cold da rk matter (CDM) critical density universes. We explore the 4-dimension al parameter space having as free parameters, Hubble's constant H-o, b aryonic fraction Omega b, the spectral slope of scalar perturbations n and the power spectrum quadrupole normalization Q. We calculate chi(2 ) minimization values and likelihood intervals for these parameters. W ithin the models considered, a low value for the Hubble constant is pr eferred: H-o = 30(-7)(+18) km s(-1) Mpc(-1). The baryonic fraction is not as well-constrained by the CMB data: Omega(b) = 0.07(-0.07)(+0.24) . The power spectrum slope is n = 0.91(-0.12)(+0.20). The power spectr um normalization is Q = 18 +/- 2.5 mu K. The error bars on each parame ter are approximately 1 sigma and are for the case where the other 3 p arameters have been marginalized. If we condition on n = 1 we obtain t he normalization Q = 17 +/- 1.0 mu K. The permitted regions of the 4-D parameter space are presented in a series of 2-D projections. In the context of the CDM critical density universes considered here, current CMB data favor a low value for the Hubble constant. Such low-H-o mode ls are consistent with Big Bang nucleosynthesis, cluster baryonic frac tions, the large-scale distribution of galaxies and the ages of globul ar clusters; although in disagreement with direct determinations of th e Hubble constant.