Dark energy as a critical phenomenon: a hint from Hubble tension

We propose a dark energy model based on the physics of critical phenomena which is consistent with both the Planck's CMB and the Riess et al.'s local Hubble measurements. In this model the dark energy density behaves like the order parameter of a generic system which undergoes a phase transition. This means the dark energy is an emergent phenomenon and we named it critically emergent dark energy model, CEDE. In CEDE, dark energy emerges at a transition redshift, z(c), corresponding to the critical temperature in critical phenomena. Combining the Planck CMB data and local measurement of the Hubble constant from Riess et al. (2019) we find statistically significant support for this transition with respect to the case of very early transition that represents effectively the cosmological constant. This is understandable since CEDE model naturally prefers larger values of Hubble constant consistent with local measurements. Since CEDE prefers a non-trivial transition when we consider both high redshift Planck CMB data and local Hubble constant measurements, we conclude that H-0 tension may be a hint for the substructure of the dark energy as a wellstudied properties of critical phenomena. However if we add BAO and SNe datasets then CEDE prefers lower value for H-0. This means the H-0 tension still exist but it is milder than Lambda CDM's.

Automated summary

A new critically emergent dark energy model (CEDE) is proposed, which is consistent with both Planck's CMB data and Riess et al.'s local Hubble constant measurements. The model suggests that dark energy emerges at a transition redshift, providing a possible explanation for the Hubble constant tension.