Hints of Dynamical Vacuum Energy in the Expanding Universe

Abstract

Recently there have been claims on model-independent evidence of dynamical dark energy. Herein we consider a fairly general class of cosmological models with a time-evolving cosmological term of the form Λ(H) = C 0 + C H H 2 + CḢḢ, where H is the Hubble rate. These models are well motivated from the theoretical point of view since they can be related to the general form of the effective action of quantum field theory in curved spacetime. Consistency with matter conservation can be achieved by letting the Newtonian coupling G change very slowly with the expansion. We solve these dynamical vacuum models and fit them to the wealth of expansion history and linear structure formation data. The results of our analysis indicate a significantly better agreement as compared to the concordance ΛCDM model, thus supporting the possibility of a dynamical cosmic vacuum.

Running vacuum cosmological models: linear scalar perturbations

“…We emphasize that the first order Boltzmann equation for massive neutrinos is reduced to the collisionless form, which can be verified by using the expression (44) in Equation (22b).…”

“…These models were confronted with observations -supernovae, baryon acoustic oscillations (BAO), CMB, and large scale structure -giving promising results [22,36,[41][42][43][44][45][46]. In another approach, the CC problems have motivated the interest on the dynamical quantum effects on the vacuum energy density in quantum field theory, and their possible link and implications to DE concept in cosmology.…”

“…Most of the cosmological constraints for this kind of models show that α must be in the range of 10 −5 − 10 −3 [24,44,45], which let us estimate δ Λ as being around δ Λ ∼ −3(1 − α)δ. The bigger amplitude of the density contrast for the vacuum components, in comparison with they material counterparts, does not represent an observational problem for the model, since such perturbations come into Einstein's equations of the form of δρ Λ = ρ Λ δ Λ ≈ α ρ δ Λ , which is suppressed by a factor α.…”

Constraining interacting dark energy models with latest cosmological observations

“…Thus the dark energy will be strengthened in the late-time Universe, and then more efficiently drive the cosmic accelerating expansion. Actually, several papers (Salvatelli et al 2014;Sola et al 2015Sola et al , 2016 have provided the first and strong indication of interaction in the dark sector recently.…”

Cosmology with Varying Constants from a Thermodynamic Viewpoint

“…We compare our model with the data from supernovae, Baryon Acoustic Oscillations (BAO), and Cosmic Microwave Background (CMB). Our model is also related to dynamical vacuum energy models, which have been discussed and confronted with data [11][12][13][14][30][31][32]. Similarly, dynamical dark energy models with varying fundamental constants have been discussed in [33,34].…”