Cosmological tests of generalized RS brane-worlds with Weyl fluid

A class of generalized Randall-Sundrum type II (RS) brane-world models with Weyl fluid are confronted with the Gold supernovae data set and BBN constraints. We consider three models with different evolutionary history of the Weyl fluid, characterized by the parameter $\alpha$. For $\alpha=0$ the Weyl curvature of the bulk appears as dark radiation on the brane, while for $\alpha =2$ and 3 the brane radiates, leaving a Weyl fluid on the brane with energy density decreasing slower than that of (dark) matter. In each case the contribution $\Omega_d$ of the Weyl fluid represents but a few percent of the energy content of the Universe. All models fit reasonably well the Gold2006 data. The best fit model for $\alpha =0$ is for $\Omega_d=0.04$. In order to obey BBN constraints in this model however, the brane had to radiate at earlier times.