No preference for generalized emergent dark energy from current cosmological data

Abstract

In this work, we revisit the generalized emergent dark energy model by confronting it with DESI DR2 baryon acoustic oscillation measurements, in combination with joint CMB data from ACT, SPT, and Planck, as well as Type Ia supernova samples including Pantheon${}^{+}$, DES-Dovekie, and Union3. We find that the GEDE model remains compatible with the $\Lambda$CDM paradigm, with no statistically significant preference for deviations when all datasets are combined. In particular, the key model parameter $\Delta$ is consistent with the $\Lambda$CDM value $\Delta =0$ within $2\sigma$ once SNe Ia data are included. Despite this overall agreement, the GEDE model does not exhibit the phantom crossing suggested by DESI DR2. Instead, the evolution of the dark energy equation of state $w(z)$ indicates that the model behaves either as a full phantom ($w<-1$) or quintessence ($w>-1$), depending on the dataset combination, without a clear transition across $w=-1$. When Pantheon${}^{+}$ data are included, the model converges closely to $\Lambda$CDM with $w\simeq -1$. The GEDE model does not alleviate the existing cosmological tensions. The inferred values of $H_0$ remain in the range $67.9$-$69.8\mathrm{km},{\mathrm{s}}^{-1},\mathrm{Mp}{\mathrm{c}}^{-1}$, while the sound horizon $r_d$ and clustering parameter $S_8$ remain consistent with $\Lambda$CDM, failing to resolve the $H_0$ and $S_8$ tensions. Finally, both Gaussian significance levels ($<2\sigma$) and Bayesian evidence ($\ln B_{i,j}<1$) indicate no statistically significant preference for GEDE over $\Lambda$CDM. We conclude that, although DESI DR2 hints at dynamical dark energy, the GEDE model remains observationally indistinguishable from $\Lambda$CDM and does not support the Quintom-B-type behavior suggested by DESI DR2.

11 pages, 3 figures, Published in Physics of the Dark Universe, Volume 53 (2026), Article 102383

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