Eur. Phys. J. C (2008) 56: 579-583
https://doi.org/10.1140/epjc/s10052-008-0678-3

Regular Article - Theoretical Physics

Viscous modified gravity on a RS brane embedded in AdS₅

Department of Energy and Process Engineering, Norwegian University of Science and Technology, 7491, Trondheim, Norway

^* e-mail: iver.h.brevik@ntnu.no

Received: 10 July 2008
Published online: 29 July 2008

Abstract

We consider a modified gravity fluid on a Randall–Sundrum II brane situated at y=0, the action containing a power α of the scalar curvature. As is known from 4D spatially flat modified gravity, the presence of bulk viscosity may drive the cosmic fluid into the phantom region (w<−1) and thereafter inevitably into the Big Rip singularity, even if it is initially nonviscous and lies in the quintessence region (w>−1). The condition for this to occur is that the bulk viscosity contains the power (2α−1) of the scalar expansion. We combine this with the 5D RS II model, and we find that the Big Rip, occurring for α>1/2, carries over to the metric for the bulk metric, |y|>0. Actually, the scale factors on the brane and in the bulk become simply proportional to each other.