Relaxing the σ₈-tension through running vacuum in the Universe

Departament de Física Quàntica i Astrofísica, and Institute of Cosmos Sciences, Universitat de Barcelona Av. Diagonal 647, E-08028 Barcelona, Catalonia, Spain

Received: 3 November 2017
Accepted: 8 January 2018

Abstract

It has recently been shown that the class of running vacuum models (RVMs) has the capacity to fit the overall cosmological observations better than the concordance ΛCDM model, therefore supporting the possibility of dynamical dark energy (DE). Apart from the cosmic microwave background (CMB) anisotropies, the most crucial datasets involved are: i) baryonic acoustic oscillations (BAO), and ii) direct large scale structure (LSS) formation data. Analyses mainly focusing on CMB and with insufficient BAO + LSS input generally fail to capture the dynamical DE signature, whereas the few existing studies accounting for the wealth of known CMB+BAO+LSS data (see in particular Solà, Gómez-Valent and de Cruz Pérez (2015), (2017); and Zhao et al. (2017)) do converge to the remarkable conclusion that dynamical DE might well be encoded in the current cosmological observations at 3–4σ c.l. A decisive factor is the persistent σ₈-tension between the ΛCDM and the data. Because the issue is obviously pressing, we devote this work to explain how and why running vacuum in the expanding universe successfully relaxes the existing σ₈-tension and describes the LSS formation data significantly better than the ΛCDM.