Hubble expansion and structure formation in the ``running FLRW model'' of the cosmic evolution

Abstract

A new class of Friedmann-Lemaître-Robertson-Walker (FLRW)cosmological models with time-evolving fundamental parameters shouldemerge naturally from a description of the expansion of the universebased on the first principles of quantum field theory and stringtheory. Within this general paradigm, one expects that both thegravitational Newton's coupling G and the cosmological term Λshould not be strictly constant but appear rather as smoothfunctions of the Hubble rate H(t).This scenario (``running FLRW model'') predicts, in a natural way,the existence of dynamical dark energy without invoking theparticipation of extraneous scalar fields.In this paper, we perform a detailed study of some of these modelsin the light of the latest cosmological data, which serves toillustrate the phenomenological viability of the new dark energyparadigm as a serious alternative to the traditional scalar fieldapproaches. By performing a joint likelihood analysis of the recentsupernovae type Ia data (SNIa), the Cosmic Microwave Background(CMB) shift parameter, and the Baryonic Acoustic Oscillations (BAOs)traced by the Sloan Digital Sky Survey (SDSS), we put tightconstraints on the main cosmological parameters. Furthermore, wederive the theoretically predicted dark-matter halo mass functionand the corresponding redshift distribution of cluster-size halosfor the ``running'' models studied. Despite the fact that thesemodels closely reproduce the standard ΛCDM Hubble expansion,their normalization of the perturbation's power-spectrum varies,imposing, in many cases, a significantly different cluster-sizehalo redshift distribution. This fact indicates that it should berelatively easy to distinguish between the ``running'' models andthe ΛCDM using realistic future X-ray and Sunyaev-Zeldovichcluster surveys.