Interacting Dark Energy after DESI Baryon Acoustic Oscillation measurements

Abstract

We investigate the implications of the Baryon Acoustic Oscillations measurement released by the Dark Energy Spectroscopic Instrument (DESI) for Interacting Dark Energy (IDE) models characterized by an energy-momentum flow from Dark Matter to Dark Energy. By combining Planck-2018 and DESI data, we observe a preference for interactions, leading to a non-vanishing interaction rate $ξ=-0.32^{+0.18}_{-0.14}$, which results in a present-day expansion rate $H_0=70.8^{+1.4}_{-1.7}$ km/s/Mpc, reducing the tension with the value provided by the SH0ES collaboration to less than $\sim 1.3 σ$. The preference for interactions remains robust when including measurements of the expansion rate $H(z)$ obtained from the relative ages of massive, early-time, and passively-evolving galaxies, as well as when considering distance moduli measurements from Type-Ia Supernovae sourced from the Pantheon-plus catalog using the SH0ES Cepheid host distances as calibrators. Overall, the IDE framework provides an equally good, or better, explanation of both high- and low-redshift background observations compared to $Λ$CDM, while also yielding higher $H_0$ values that align more closely with the local distance ladder estimates. However, a limitation of the IDE model is that it predicts lower $Ω_{m}$ and higher $σ_{8}$ values, which may not be fully consistent with large-scale structure data at the perturbation level.

Figures (4)

• Figure 1: 2D contours at $68\%$ and $95\%$ CL for the coupling parameter $\xi$ and the Hubble parameter $H_0$, as inferred by the different combinations of Planck-2018, DESI, and SN data listed in the legend. The olive-green band represents the value of $H_0$ measured by the SH0ES collaboration.
• Figure 2: Upper panel: Best-fit predictions for (rescaled) distance-redshift relations for IDE (solid curves) and $\Lambda$CDM (dashed curves) obtained from the analysis of Planck-2018+DESI data. These predictions are presented for the three different types of distances probed by BAO measurements, each indicated by the colors reported in the legend. The error bars represent $\pm 1 \sigma$ uncertainties. Lower panel: Difference between the model prediction and data-point for each BAO measurement, normalized by the observational uncertainties. The IDE predictions are represented by 'x'-shaped points while the $\Lambda$CDM predictions are represented by 'o'-shaped points.
• Figure 3: Statistical reconstruction of the (rescaled) expansion rate of the universe $H(z)/(1+z)$ at 1$\sigma$ and 2$\sigma$ confidence levels for $\Lambda$CDM and IDE models through the joint analysis of Planck-2018+DESI+SN+CC, compared to DESI measurements.
• Figure 4: 2D contours at 68% and 95% CL for the coupling parameter $\xi$ and the Hubble parameter $H_0$, as inferred by the different combinations of Planck-2018, DESI, and SDSS data listed in the legend. The olive-green band represents the value of $H_0$ measured by the SH0ES collaboration.