Is excess smoothing of Planck CMB anisotropy data partially responsible for evidence for dark energy dynamics in other w (z) CDM parametrizations?

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Abstract

In this paper, we study spatially-flat dynamical dark energy parametrizations, w(z)CDM, with redshift-dependent dark energy equation of state parameter w(z) expressed using three different quadratic and other polynomial forms (as functions of 1-a, where a is the scale factor), without and with a varying cosmic microwave background (CMB) lensing consistency parameter AL. 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 (H(z)), and growth factor (fσ8) measurements, but not recent DESI BAO data. The six w(z)CDM (+AL) parametrizations show higher consistency between the CMB and non-CMB data constraints compared to the XCDM (+AL) and w0waCDM (+AL) cases. Constraints from the most-restrictive P18+lensing+non-CMB data compilation on the six w(z)CDM (+AL) parametrizations indicate that dark energy dynamics is favored over a cosmological constant by ≳2σ when AL=1, but only by ≳1σ when AL is allowed to vary (and AL>1 at ∼2σ 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 1.5σ to 2.9σ when AL=1, and from 1.1σ to 1.8σ when AL varies. These results suggest that the observed excess weak lensing smoothing of some of the Planck CMB anisotropy multipoles is partially responsible for the AL=1 cases ≳2σ evidence for dark energy dynamics over a cosmological constant.

Original languageEnglish
Article number2550061
JournalInternational Journal of Modern Physics D
Volume34
Issue number13
DOIs
StatePublished - 2025.10.15

Keywords

  • cosmic background radiation
  • cosmological parameters
  • Dark energy

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