Evidence for Emergent Dark Energy

We introduce a generalized form of an emergent dark energy model with one degree of freedom for the dark energy sector that has the flexibility to include both the ΛCDM model as well as the Phenomenologically Emergent Dark Energy (PEDE) model proposed by Li & Shafieloo as two of its special limits. The free parameter for the dark energy sector, namely Δ, has a value of 0 for the Λ case and a value of 1 for the PEDE case. Fitting the introduced parametric form to Planck cosmic microwave background (CMB) data and recent H ₀ results from local observations of cepheids and supernovae, we show that the Δ = 0 associated with the ΛCDM model would fall out of the 4σ confidence limits of the derived posterior of the Δ parameter. Moreover, H ₀ tensions with the emergent dark energy model will be alleviated and this model can satisfy the combination of Planck CMB data and local H ₀ observations with ΔDIC = −2.88 compared with the ΛCDM model.