Abstract
We study three interacting dark energy models within the framework of four-dimensional General Relativity and a spatially flat Universe. In particular, we first consider two vacuum models where dark energy interacts with dark matter, while relativistic matter as well as baryons are treated as non-interacting fluid components. Secondly, we investigate a third model where the gravitational coupling is assumed to be a slowly-varying function of the Hubble rate and dark energy and dark matter interact as well. We compute the statefinders parameters versus red-shift as well as the critical points and their nature applying dynamical systems methods. In the case of only an interaction term, our main findings indicate that (i) significant differences between the models are observed as we increase the strength of the interaction term, and (ii) all the models present an unique attractor corresponding to acceleration. On the other hand, when we allow for a variable gravitational coupling, we find that (i) the deviation from the concordance model depends of both the strength of gravitational coupling parameter and the interaction term, and (ii) there is an unique attractor corresponding to acceleration.
Highlights
Regarding the cosmological constant (CC) problem and possible alternatives to the CDM model, either a modified theory of gravity is assumed, providing correction terms to GR at cosmological scales, or a new dynamical degree of freedom with an equation-of-state (EOS) parameter w < −1/3 must be introduced
C (2020) 80:286 contrary to a rigid cosmological constant = const., vacuum energy density can be expressed as a function of the Hubble rate, i.e. ρ = ρ (H ), being of dynamical nature and at the same time it may interacts with dark matter, and it accounts for a running of the gravitational coupling G [47]
Considering that running vacuum (RVM) models offers an interesting framework to study phenomenology beyond to CDM model, the main goal of the present work is to analyse three models within the running vacuum dynamics: we first consider two vacuum models where dark energy interacts with dark matter [46], and secondly, we investigate a third model where the gravitational coupling is assumed to be a slowly-varying function of the Hubble rate [47] and dark energy and dark matter interact as well
Summary
Regarding the CC problem and possible alternatives to the CDM model, either a modified theory of gravity is assumed, providing correction terms to GR at cosmological scales, or a new dynamical degree of freedom with an equation-of-state (EOS) parameter w < −1/3 must be introduced. What is more, regarding large scale structure formation data, the growth rate from red-shift space distortion measurements has been found to be lower than expected from PLANCK [38,39] Both tensions may be alleviated within the framework of running vacuum dynamics [40,41,42,43,44,45,46]. J. C (2020) 80:286 contrary to a rigid cosmological constant = const., vacuum energy density can be expressed as a function of the Hubble rate, i.e. ρ = ρ (H ), being of dynamical nature and at the same time it may interacts with dark matter, and it accounts for a running of the gravitational coupling G [47].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
