1208.6327 (C. E. M. Batista et al.)

Observational constraints on Rastall's cosmology    [PDF]

C. E. M. Batista, J. C. Fabris, O. F. Piattella, A. M. Velasquez-Toribio

Rastall's theory is a modification of General Relativity, based on non-conservation of the stress-energy tensor. The latter is encoded in a parameter $\gamma$ such that $\gamma = 1$ restores the usual $T^{\mu\nu}{}_{;\nu} = 0$ law. We test Rastall's theory in cosmology, investigating a two-fluid model and using data from type Ia supernovae and large scale structure observation. In our model, one of the fluids possesses zero pressure and obeys the usual conservation law, whereas the other is described by an equation of state $p_x = \omega_x\rho_x$, with $\omega_x$ constant. Confrontation against observational data favours a scenario with $\gamma \sim 2$ (which curiously corresponds to the original formulation of General Relativity, based on the Ricci tensor) and $\omega_x \sim - 1$.

View original: http://arxiv.org/abs/1208.6327