Updated observational constraints on spatially flat and nonflat ΛCDM and XCDM cosmological models

We study the performance of six cold dark matter () models, with four of them allowing for nonflat spatial hypersurfaces (nonzero current value of the spatial curvature density parameter ₊) and three of them allowing for a nonunity value of the lensing consistency parameter A₋. We also study a set of six XCDM models where the nonevolving cosmological constant dark energy density is replaced by a dynamical dark energy density X-fluid parametrized by a nonevolving equation of state parameter w. For the nonflat models we consider two different primordial power spectra, Planck P (q), used by the Planck collaboration, and new P (q), resulting from quantum fluctuations in a not-necessarily-very-slow-roll nonflat inflation model. These models are constrained by and tested against: Planck 2018 CMB temperature and polarization power spectra data (P18) ; Planck 2018 CMB lensing potential power spectrum data (lensing) ; and, an updated compilation of baryon acoustic oscillation, type Ia supernova, Hubble parameter H (z), and growth factor f₈ data points collectively denoted by non-CMB (new) data, individually and jointly. P18 data favor ₊0 (open geometry) in the case of the models and ₊-1 (quintessencelike dynamical dark energy) for the XCDM models. When P18 and non-CMB (new) data are jointly analyzed there is weak evidence in favor of open spatial geometry and moderate evidence in favor of quintessencelike dynamical dark energy. On the other hand, regardless of data considered, A₋>1 is always favored, with different degrees of evidence, even for P18+lensing+non-CMB (new) data. According to Akaike and deviance information criterion results, A₋-varying models are positively favored over the flat model for P18+lensing+non-CMB (new) data. The XCDM model cosmological parameter constraints obtained from P18 or P18+lensing data and from non-CMB (new) data are incompatible at >3, ruling out the three A₋=1 XCDM models at >3. In the nine models not ruled out by >3 incompatibilities between parameter values determined from different datasets, for the P18+lensing+non-CMB (new) dataset we find little deviation from flat geometry and moderate deviation from a cosmological constant. In all six nonflat models that are not ruled out at >3, open geometry is mildly favored (by at most 0. 8), and in all three XCDM+A₋ models (that are not ruled out at >3) quintessencelike dynamical dark energy is moderately favored (by at most 1. 6). In the A₋=1 nonflat cases, we find for P18+lensing+non-CMB (new) data ₊=0. 00090. 0017 0. 00080. 0017 for the Planck new P (q) model, favoring open geometry at 0. 53 0. 47. Given these results, the flat model remains the simplest (largely) observationally-consistent cosmological model. Our cosmological parameter constraints obtained for the flat model (and other models), when P18+lensing+non-CMB (new) data are considered, are the most restrictive results to date.