Graduated dark energy: Observational hints of a spontaneous sign switch in the cosmological constant

• DOI: 10.1103/physrevd.101.063528
• Publication Date: 2020-03-25T15:55:49Z
• Authors: Özgür Akarsu; John D. Barrow; Luis A. Escamilla; J. Alberto Vazquez
• Keywords: Maxima; Cosmological constant

We study the cosmological constant ($\Lambda$) in standard $\Lambda$CDM model by introducing \textit{graduated dark energy} (gDE) characterised a minimal dynamical deviation from null inertial mass density of $\Lambda$ form $\rho_{\rm inert}\propto \rho^{\lambda}<0$ with $\lambda<1$ being ratio two odd integers, for which its energy $\rho$ dynamically takes negative values finite past. For large $\lambda$, it creates phenomenological described smooth function that approximately describes spontaneously switching sign late universe to become positive today. confront latest combined observational data sets PLK+BAO+SN+$H$. It is striking predict bimodal posterior probability distributions parameters along $\lambda$ values; new maximum significantly excludes $\Lambda$, and old contains $\Lambda$. The improvement goodness fit reaches highly significant levels, $\Delta\chi_{\rm min}^2=6.4$ maxima, while remains at insignificant min}^2\lesssim0.02$, maxima. show that, contrast do not distinguish maxima agree model-independent $H_0$ measurements, high-precision Ly-$\alpha$ data, $Omh^2$ diagnostic estimates. Our results provide strong hints spontaneous switch lead us conjecture has transitioned AdS vacua dS vacua, redshift $z\approx 2.32$ triggered late-time acceleration, suggests looking such mechanisms string theory constructions.