COBE-DMR normalization for inflationary flat dark matter models

The two-year COBE-DMR 53 and 90 GHz sky maps, in both galactic and eclipticcoordinates, are used to determine the normalisation of inflationary universemodels with a flat global geometry and adiabatic density perturbations. Theappropriately normalised cold and mixed dark matter models and cosmologicalconstant dominated, cold dark matter models, computed for a range of values ofOmega_b and h, are then compared to various measures of structure in theuniverse. Critical density CDM models appear to be irreconcilable withobservations on both large and small scales simultaneously, whereas MDM modelsprovide a somewhat better fit to the data. Although the COBE-DMR data aloneprefer a nearly critical value for the total density, low-density cosmologicalconstant models with Omega_0 greater than or equal to 0.15 can not be rejectedat a confidence level exceeding 95%. Such models may also provide asignificantly better fit to the matter distribution data than critical densityCDM.Comment: uuencoded postscript file (complete text and figures). Accepted for publication in MNRA