Evidence for Emergent Dark Energy

Understand

We introduce a generalised form of an emergent dark energy model with one degree of freedom for the dark energy sector that has the flexibility to include both $\Lambda$CDM model as well as the Phenomenologically Emergent Dark Energy (PEDE) model proposed by Li & Shafieloo (2019) as two of its special limits.

• The free parameter for the dark energy sector, namely $\Delta$, has the value of $0$ for the case of the $\Lambda$ and $1$ for the case of PEDE.
• Fitting the introduced parametric form to Planck CMB data and most recent $H_0$ results from local observations of Cepheids and Supernovae, we show that the $\Delta=0$ associated with the $\Lambda$CDM model would fall out of 4$\sigma$ confidence limits of the derived posterior of the $\Delta$ parameter.
• Moreover, $H_0$ tensions will be alleviated with emergent dark energy model and this model can satisfy the combination of Planck CMB data and local $H_0$ observations with $\Delta{\rm{DIC}}\,=\,-2.88$ compared with $\LCDM$ model.