Observational constraints on the tilted flat-XCDM and the untilted
  nonflat XCDM dynamical dark energy inflation parameterizations
  We constrain tilted spatially-flat and untilted nonflat XCDM dynamical dark
energy inflation parameterizations using Planck 2015 cosmic microwave
background (CMB) anisotropy data and recent baryonic acoustic oscillations
distance measurements, Type Ia supernovae data, Hubble parameter observations,
and growth rate measurements. Inclusion of the four non-CMB data sets results
in a significant strengthening of the evidence for nonflatness in the nonflat
XCDM model from 1.1$\sigma$ for the CMB data alone to 3.4$\sigma$ for the full
data combination. In this untilted nonflat XCDM case the data favor a
spatially-closed model in which spatial curvature contributes a little less
than a percent of the current cosmological energy budget; they also mildly
favor dynamical dark energy over a cosmological constant at 1.2$\sigma$. These
data are also better fit by the flat-XCDM parameterization than by the standard
$\Lambda$CDM model, but only at 0.3$\sigma$ significance. Current data is
unable to rule out dark energy dynamics. The nonflat XCDM parameterization is
compatible with the Dark Energy Survey limits on the present value of the rms
mass fluctuations amplitude ($\sigma_8$) as a function of the present value of
the nonrelativistic matter density parameter ($\Omega_m$), however it does not
provide as good a fit to the higher multipole CMB temperature anisotropy data
as does the standard tilted flat-$\Lambda$CDM model. A number of measured
cosmological parameter values differ significantly when determined using the
tilted flat-XCDM and the nonflat XCDM parameterizations, including the baryonic
matter density parameter and the reionization optical depth.
