Dark-fluid constraints of shear-free universes

Abstract

Integrability conditions arising from general irrotational fluid-flow considerations of a universe dominated by cosmic dark fluids will be investigated under special assumptions on the nature of the spacetime shear. Special emphasis will be placed on linearized perturbations of quasi-Newtonian and anti-Newtonian spacetimes, whereby the conditions for the existence and consistent evolution of such spacetimes in the presence of the Chaplygin gas fluid model will be derived and discussed.

4+2 pages, no figures. Accepted for publication in Proceedings of the African Conference on Fundamental and Applied Physics (ACP2021)