Abstract
Despite the outstanding achievements of modern cosmology, the classical dispute on the precise value of H0, which is the first ever parameter of modern cosmology and one of the prime parameters in the field, still goes on and on after over half a century of measurements. Recently the dispute came to the spotlight with renewed strength owing to the significant tension (at >3σ c.l.) between the latest Planck determination obtained from the CMB anisotropies and the local (distance ladder) measurement from the Hubble Space Telescope (HST), based on Cepheids. In this work, we investigate the impact of the running vacuum model (RVM) and related models on such a controversy. For the RVM, the vacuum energy density ρΛ carries a mild dependence on the cosmic expansion rate, i.e. ρΛ(H), which allows to ameliorate the fit quality to the overall SNIa+BAO+H(z)+LSS+CMB cosmological observations as compared to the concordance ΛCDM model. By letting the RVM to deviate from the vacuum option, the equation of state w=−1 continues to be favored by the overall fit. Vacuum dynamics also predicts the following: i) the CMB range of values for H0 is more favored than the local ones, and ii) smaller values for σ8(0). As a result, a better account for the LSS structure formation data is achieved as compared to the ΛCDM, which is based on a rigid (i.e. non-dynamical) Λ term.
Highlights
The most celebrated fact of modern observational cosmology is that the universe is in accelerated expansion [1, 2]
The dynamical vacuum models (DVMs) can provide an excellent fit to the overall cosmological observations and be fully compatible with both the H0Planck value and at the same time with the needed low values of the σ8(0) observable, these low values of σ8(0) being crucial to fit the structure formation data. Such strategy is only possible in the presence of vacuum dynamics, whilst it is impossible with a rigid Λ-term, i.e. is not available to the ΛCDM
Our results suggest a dynamical dark energy (DE) effect near 3σ within the standard XCDM parametrization and near 4σ for the best DVMs
Summary
The most celebrated fact of modern observational cosmology is that the universe is in accelerated expansion [1, 2]. In the recent literature, between the latest Planck values (H0Planck) obtained from the CMB anisotropies, and the local HST measurement (based on distance ladder estimates from Cepheids). The latter, obtained by Riess et al [13], is H0 = 73.24 ± 1.74 km/s/Mpc and will be denoted H0Riess. 3.1σ and 3.4σ, respectively) with respect to the local measurement This situation, and in general a certain level of tension with some independent observations in intermediate cosmological scales, has stimulated a number of discussions and possible solutions in the literature, see e.g. Our analysis corroborates that the large scale structure formation data (LSS) are crucial in distinguishing the rigid vacuum option from the dynamical one
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