Constraining dark energy dynamics in extended parameter space

Dynamical dark energy has been recently suggested as a promising and physical way to solve the 3sigma tension on the value of the Hubble constantH0between the direct measurement of Riesset al.(2016)(R16, hereafter) and the indirect constraint from cosmic microwave anisotropies obtained by the Plancksatellite under the assumption of aΛCDM model. In this paper, by parametrizing dark energy evolutionusing thew0−waapproach, and considering a 12 parameter extended scenario, we find that: (a) the tensionon the Hubble constant can indeed be solved with dynamical dark energy, (b) a cosmological constant isruled out at more than 95% c.l. by the PlanckþR16dataset, and (c) all of the standard quintessence andhalf of the“downward going”dark energy model space (characterized by an equation of state that decreaseswith time) is also excluded at more than 95% c.l. These results are further confirmed when cosmic shear,CMB lensing, or SN Ia luminosity distance data are also included. The best fit value of theχ2for thePlanckþR16data set improves byΔχ2¼−12.9when moving to 12 parameters respect to standardΛCDM. However, tension remains with the BAO dataset. A cosmological constant and small portion of thefreezing quintessence models are still in agreement with the PlanckþR16þBAO data set at between 68%and 95% c.l. Conversely, for Planck plus a phenomenologicalH0prior, both thawing and freezingquintessence models prefer a Hubble constant of less than70km=s=Mpc. The general conclusions holdalso when considering models with nonzero spatial curvature