Speaker
Description
Recent data has pointed out that dark energy may not be consistent with a cosmological constant. Combined datasets increasingly indicate that its equation of state may exhibit dynamical behavior, potentially crossing the “phantom divide” ($w < -1$) at low redshifts. This feature has been discussed as one possible aspect of the so-called BAO tension and is difficult to reproduce within simple quintessence models without invoking exotic kinetic terms or non-minimal couplings. An exciting possibility is to introduce an interaction in the dark sector, in which case a simple reparameterization of the effective equation of state suffices to produce an effective phantom behavior. Recent studies have further suggested that this tension may be a “mirage” arising from neglecting dark sector interactions in the standard CPL parameterization used to fit observational data. In this work, we show how effective phantom behavior may arise in a hybrid scalar-field model and determine the conditions under which this occurs. We show that this model presents an apparent equation of state with phenomenology similar to the CPL at late times, but only upon the addition of a self-interaction potential, showcasing similarities with thawing quintessence models reported in the literature. We confront this model with datasets to investigate whether it can alleviate this tension.