Using the Tilted flat-ΛCDM and the Untilted Non-flat ΛCDM Inflation Models to Measure Cosmological Parameters from a Compilation of Observational Data

摘要

We use the physically-consistent tilted spatially-flat and non-flat$Lambdaextrm{CDM}$ inflation models to constrain cosmological parametervalues with the Planck 2015 cosmic microwave background (CMB) anisotropy dataand recent Type Ia supernovae measurements, baryonic acoustic oscillations(BAO) data, growth rate observations, and Hubble parameter measurements. Themost dramatic consequence of including the four non-CMB data sets is thesignificant strengthening of the evidence for non-flatness in the non-flat$Lambda$CDM model, from 1.8$sigma$ for the CMB data alone to 5.1$sigma$ forthe full data combination. The BAO data is the most powerful of the non-CMBdata sets in more tightly constraining model parameter values and in favoring aspatially-closed Universe in which spatial curvature contributes about apercent to the current cosmological energy budget. The non-flat $Lambda$CDMmodel better fits the large-angle CMB anisotropy angular spectrum and is moreconsistent with the Dark Energy Survey constraints on the current value of therms amplitude of mass fluctuations ($sigma_8$) as a function of the currentvalue of the nonrelativistic matter density parameter ($Omega_m$) but does notprovide as good a fit to the smaller-angle CMB anisotropy data as does thetilted flat-$Lambda$CDM model. Some measured cosmological parameter valuesdiffer significantly between the two models, including the reionization opticaldepth and the baryonic matter density parameter, both of whose 2$sigma$ ranges(in the two models) are disjoint or almost so.