Cosmological interaction of vacuum energy and dark matter

Abstract

Models which allow for an evolving cosmological constant [alfa] are an alternative to the [alfa]CDM model, with a rigid [alfa] term. An evolving [alfa] leads to a coupling of dark energy (associated with the vacuum energy ) either to matter or to the gravitational constant G, which hints that an interaction of dark energy could be present. We study the dynamical vacuum models proposed by (Salvatelli et al, 2014) and (Solà et al, 2015 and 2016), which are based on different assumptions on the evolution. We solve both models and find an effective equation of state for dark energy in each case, recovering the results found by (Solà et al, 2015 and 2016), and find that their effective behavior can be related to that of phantom fields or quintessence models. A recent reanalysis of the (Salvatelli et al, 2014) scenario by the last authors leads to different conclusions more in accordance with observations. Interestingly, the dynamical vacuum models are currently challenging the [alfa]CDM