In the Randall-Sundrum scenario we analize the dynamics of a spherically symmetric 3-brane when matter fields propagate in the bulk. For a well defined class of conformal fields of weight -4 we determine a new set of exact 5-dimensional solutions which localize gravity in the vicinity of the brane and are stable under radion field perturbations. Geometries which describe the dynamics of inhomog...

The canonical redshift−scale factor relation, 1/a = 1 + z, is a key element in the standard ΛCDM model of the big bang cosmology. Despite its fundamental role, this relation has not yet undergone any observational tests since Lemaı̂tre and Hubble established the expansion of the Universe. It is strictly based on the assumption of the Friedmann–Lemaı̂tre–Robertson–Walker metric describing a locall...

We investigate the growth of matter density perturbations as well as the generalized second law (GSL) of thermodynamics in the framework of f(R)-gravity. We consider a spatially flat FRW universe filled with the pressureless matter and radiation which is enclosed by the dynamical apparent horizon with the Hawking temperature. For some viable f(R) models containing the Starobinsky, Hu-Sawicki, Exp...

Modifications of general relativity provide an alternative explanation to dark energy for the observed acceleration of the Universe. Modified gravity theories have richer observational consequences for large scale structures than conventional dark energy models, in that different observables are not described by a single growth factor even in the linear regime. We examine the relationships betw...

The holographic dark energy model is an attempt for probing the nature of dark energy within the framework of quantum gravity. The dimensionless parameter c determines the main property of the holographic dark energy. With the choice of c ≥ 1, the holographic dark energy can be described completely by a quintessence scalar field. In this paper, we show this quintessential description of the hol...