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Is the w0waw_0w_aCDM cosmological parameterization evidence for dark energy dynamics partially caused by the excess smoothing of Planck CMB anisotropy data?

Chan-Gyung Park,Javier de Cruz Pérez,Bharat Ratra

2024 · ArXiv: 2410.13627
14 Citations

Abstract

We study the performance of the spatially-flat dynamical dark energy (DE) w0waw_0w_aCDM parameterization, with redshift-dependent DE fluid equation of state parameter w(z)=w0+waz/(1+z)w(z) = w_0 + w_a z/(1+z), with and without a varying CMB lensing consistency parameter ALA_L, against Planck cosmic microwave background (CMB) data (P18 and lensing) and a combination of non-CMB data composed of baryonic acoustic oscillation (BAO) measurements that do not include DESI BAO data, Pantheon+ type Ia supernovae (SNIa) observations, Hubble parameter [H(z)H(z)] measurements, and growth factor (fσ8f\sigma_8) data points. From our most restrictive data set, P18+lensing+non-CMB, for the w0waw_0w_aCDM+ALA_L parameterization, we obtain w0=0.879±0.060w_0=-0.879\pm 0.060, wa=0.390.22+0.26w_a=-0.39^{+0.26}_{-0.22}, the asymptotic limit w(z)=w0+wa=1.270.17+0.20w(z\to\infty) = w_0+w_a=-1.27^{+0.20}_{-0.17}, and AL=1.0780.040+0.036A_L=1.078^{+0.036}_{-0.040} (all 1σ1\sigma errors). This joint analysis of CMB and non-CMB data favors DE dynamics over a cosmological constant at 1σ\sim 1\sigma and AL>1A_L>1 at 2σ\sim 2\sigma, i.e. more smoothing of the Planck CMB anisotropy data than is predicted by the best-fit model. For the w0waw_0w_aCDM parameterization with AL=1A_L=1 the evidence in favor of DE dynamics is larger, 2σ\sim 2\sigma, suggesting that at least part of the evidence for DE dynamics comes from the excess smoothing of the Planck CMB anisotropy data. For the w0waw_0w_aCDM parameterization with AL=1A_L=1, there is a difference of 2.8σ2.8\sigma between P18 and non-CMB cosmological parameter constraints and 2.7σ2.7\sigma between P18+lensing and non-CMB constraints. When ALA_L is allowed to vary these tensions reduced to 1.9σ1.9\sigma and 2.1σ2.1\sigma respectively. Our P18+lensing+non-CMB data compilation positively favors the w0waw_0w_aCDM parameterization without and with a varying ALA_L parameter over the flat Λ\LambdaCDM model, and w0waw_0w_aCDM+ALA_L is also positively favored over w0waw_0w_aCDM.