Dynamical Oscillations in Dark Energy: Joint Constraints on the $w_{sin}$CDM Model from DESI, OHD, and Supernova Samples

TL;DR

This study tests an oscillatory dark-energy model, $w_{ m de}(a)=w_0+w_a[a\sin(1/a)-\sin(1)]$, within the $w_{ m sin}$CDM framework using joint constraints from DESI BAO, OHD, Pantheon Plus, and SH0ES. The authors implement a flat FLRW background and perform MCMC analyses with CLASS and MontePython to constrain $w_0$, $w_a$, $H_0$, and $\Omega_m$, comparing against $\Lambda$CDM and CPL parametrizations. Across data combinations, they find a mild dynamical quintessence behavior ($w_0>-1$, $w_a<0$) with DESI data tightening degeneracies, while $\Lambda$CDM remains compatible at $2\sigma$ for DESI+OHD+PP and the Hubble tension is partially alleviated when SH0ES is included (e.g., $H_0=71.85\pm0.79$ km s$^{-1}$ Mpc$^{-1}$ for DESI+OHD+PP+SH0ES, reducing tension to $\lesssim1\sigma$). The model yields $q_0\approx -0.36$ and $w_{ m eff}\approx -0.57$ for the combined dataset, with $\Omega_m\approx0.32$ and $t_0\approx13.0$ Gyr; analysis with DR2+OHD+DES-5yr indicates stronger departure from $w=-1$ ($4\sigma$) for $w_0$, while SN data favor higher $\Omega_m$. Overall, $w_{ m sin}$CDM provides a viable, competitive alternative to CPL/BA parametrizations, offering non-monotonic EoS features that can modestly ease the Hubble tension and warrant further testing with forthcoming DESI data.

Abstract

In this study, we investigate the oscillatory dark energy model $w_{\sin}\mathrm{CDM}$ based on the DESI BAO data together with OHD, Pantheon Plus, and SH0ES measurements. We examine how the DESI data influence the dark energy equation-of-state plane $(w_0, w_a)$ within cosmological models that are free from Hubble tension and employ a Monte Carlo Markov Chain (MCMC) approach. Our findings indicate that although the parameter space still favors $w_a < 0$ and $w_0 > -1$ , the cosmological constant remains consistent with the DESI+OHD+PP combination at the $2σ$ level. We also observe that the best-fit Hubble constant $H_0$ is higher for the DESI+OHD+PP+SH0ES data combination, leading to a residual Hubble tension of less than $1σ$ to remain consistent with the SH0ES measurement. These results suggest that attempts to address the Hubble tension tend to reduce indication of DESI for the oscillatory dark energy model. Therefore, claims that the cosmological constant should be approached with greater caution, considering both the latest observational datasets and the existing cosmological tensions. We also obtained the present deceleration parameter and the effective equation-of-state value as $q_0 = -0.36$ and $w_{\mathrm{eff}} = -0.57$, respectively, for the DESI+OHD+PP+SH0ES dataset combination. Further analysis indicated a strong departure of $w_0$ from $w=-1$ at the $4σ$ level for the DR2+OHD+DES-5yr data combination. The inferred $Ω_{m}$ tended to shift toward higher values when supernova samples were included, indicating a systematic preference for larger $Ω_{m}$ in combinations involving supernova data.

Figures (9)

• Figure 1: The 2D plot between $H(z)$ verse $z$ for our model and $\Lambda$CDM model from $33$ OHD data points with black error bar.
• Figure 2: The 2D plot between $\mu(z)$ verse $z$ for our model and $\Lambda$CDM model from $1701$ PP data points with green error bar.
• Figure 3: In this figure, the left panel shows the 2D contour between $H_0$ and $w_a$ overlaid with SHOES and TRGB bands, while right panel displays 2D contour between $H_0$ and $w_0$ with the same external bands. These contour obtained from $w_{sin}$CDM model based on all the given dataset combinations is presented in first row of Table \ref{['tab1']}.
• Figure 4: The $\Delta$AIC value of our model relative to the standard $\Lambda$CDM model for all the given dataset combinations is presented in first row of Table \ref{['tab1']}.
• Figure 5: The 2D plot between $q(z)$ verse z for our model and $\Lambda$CDM model from DESI+OHD+PP+SH0ES data sets with 1$\sigma$ error bar.