In this paper, we study spatially-flat dynamical dark energy parametrizations, Formula: see textCDM, with redshift-dependent dark energy equation of state parameter Formula: see text expressed using three different quadratic and other polynomial forms (as functions of Formula: see text, where a is the scale factor), without and with a varying cosmic microwave background (CMB) lensing consistency parameter Formula: see text. We use Planck CMB anisotropy data (P18 and lensing) and a large, mutually-consistent non-CMB data compilation that includes Pantheon+ type Ia supernova, baryon acoustic oscillation (BAO), Hubble parameter (Formula: see text), and growth factor (Formula: see text) measurements, but not recent DESI BAO data. The six Formula: see textCDM (Formula: see text) parametrizations show higher consistency between the CMB and non-CMB data constraints compared to the XCDM (Formula: see text) and Formula: see textCDM (Formula: see text) cases. Constraints from the most-restrictive P18+lensing+non-CMB data compilation on the six Formula: see textCDM (Formula: see text) parametrizations indicate that dark energy dynamics is favored over a cosmological constant by Formula: see text when Formula: see text, but only by Formula: see text when Formula: see text is allowed to vary (and Formula: see text at Formula: see text significance). Non-CMB data dominate the P18+lensing+non-CMB compilation at low z and favor quintessence-like dark energy. At high z P18+lensing data dominate, favoring phantom-like dark energy with significance from Formula: see text to Formula: see text when Formula: see text, and from Formula: see text to Formula: see text when Formula: see text varies. These results suggest that the observed excess weak lensing smoothing of some of the Planck CMB anisotropy multipoles is partially responsible for the Formula: see text cases Formula: see text evidence for dark energy dynamics over a cosmological constant.
Park et al. (Wed,) studied this question.