Updated observational constraints on $\varphi$CDM dynamical dark energy cosmological models

Abstract

We present updated observational constraints on the spatially flat $\varphi$CDM model, where dark energy is described by a minimally coupled scalar field $\varphi$ with an inverse power-law potential $V=V_0{\varphi }^{-\alpha }$. Using Planck 2018 CMB temperature, polarization (P18), and lensing power spectra (lensing), along with a compilation of non-CMB data including baryon acoustic oscillation, type Ia supernova, Hubble parameter, and growth rate measurements, we constrain $\varphi$CDM and $\varphi$CDM+$A_L$ models where $A_L$ is the CMB lensing consistency parameter. The scalar field parameter $\alpha$, which governs dark energy dynamics, is more tightly constrained by non-CMB data than by CMB data alone. For the full dataset, we obtain $\alpha =0.055\pm 0.041$ in the $\varphi$CDM model and $\alpha =0.095\pm 0.056$ in the $\varphi$CDM+$A_L$ model, mildly favoring evolving dark energy over a cosmological constant by $1.3\sigma$ and $1.7\sigma$. The Hubble constant is $H_0=67.55_{-0.46}^{+0.53}$ km s${}^{-1}$ Mpc${}^{-1}$ in the $\varphi$CDM model, consistent with median statistics and some local determinations, but in tension with other local determinations. The constraints for matter density and clustering amplitude (${\Omega }_m=0.3096\pm 0.0055$, ${\sigma }_8=0.8013_{-0.0067}^{+0.0077}$) of the flat $\varphi$CDM model statistically agree with $\Lambda$CDM model values. Allowing $A_L$ to vary reduces tensions between CMB and non-CMB data, although we find $A_L=1.105\pm 0.037$, $2.8\sigma$ higher than unity, consistent with the excess smoothing seen in Planck data. Model comparison using AIC and DIC indicates that the $\varphi$CDM model provides a fit comparable to $\Lambda$CDM, with the $\varphi$CDM+$A_L$ slightly preferred. Overall, while the $\Lambda$CDM model remains an excellent fit, current data leave open the possibility of mildly evolving quintessence-like dynamical dark energy.

Comments: 22 pages, 6 figures, 4 tables. Accepted for publication in International Journal of Modern Physics D