Updated observational constraints on quintessence dark energy models

Abstract

The recent GW170817 measurement favors the simplest dark energy models, such as a single scalar field. Quintessence models can be classified in two classes, freezing and thawing, depending on whether the equation of state decreases towards −1 or departs from it. In this paper we put observational constraints on the parameters governing the equations of state of tracking freezing, scaling freezing and thawing models using updated data, from the Planck 2015 release, joint lightcurve analysis and baryonic acoustic oscillations. Because of the current tensions on the value of the Hubble parameter H0, unlike previous authors, we let this parameter vary, which modifies significantly the results. Finally, we also derive constraints on neutrino masses in each of these scenarios.

Fine-structure constant constraints on late-time dark energy transitions

“…Our analysis complements and extends that of [5] and of other recent works [24,25,26]. While each of these works constrains specific model classes, they confirm that Figure 4: Comparison of the posterior likelihoods for w i (top panels) and w 0 (bottom panels).…”

“…In other words, such models have a non-zero amount of early dark energy [29], which is constrained by Cosmic Microwave Background experiments such as Planck to sub-percent level [4]. The second particular case corresponds to fixing ∆ = 1/3, as recently done in [26], on the grounds that this is the value for which this parametrisation best approximates the dynamics of a specific sub-class of quintessence models known as scaling freezing models. Figure 1 and Table 1 summarize this analysis, which improves upon and updates that of [5].…”

Testing the Swampland: H0 tension

“…The answer seems NO! Note, there are various recent studies of Quintessence in the literature and the tension cannot be relieved [22][23][24][25], so this conclusion is not overly surprising.…”

Constraints on field flows of quintessence dark energy

“…The inferred range of λ 1 is determined by the scaling property of the EXP potential λ 1 ∼ Ω −1/2 i , so that a broad upper bound is always found (the lower prior λ 1 > 9.4 is not explicited in the tables). The other parameter of the model µ = V 2 /V 1 , usually assumed to unity in standard analysis [32,45,96], is constrained by our MCMC study and it corresponds to log 10 µ = −2.6 +1.3 −1.4 . The smallness of µ is expected in order to realize the condition e −λ1φ ≫ µe −λ2φ , thus ensuring the scaling solution at early times.…”

“…To the best of our knowledge our study is the first that implements such a comprehensive analysis of DEXP. Indeed in [96] it was fixed µ = 1 and parameters constraints were inferred from the profile of the likelihood in a reduced parameter space, while in [32] only a fitting parametrization of the figure fig. 3.…”