Partial rip scenario - a cosmology with a growing cosmological term

Abstract

A cosmology with the growing cosmological term is considered. If there is no exchange of energy between vacuum and matter components, the requirement of general covariance implies the time dependence of the gravitational constant $G$. Irrespectively of the exact functional form of the cosmological term growth, the universe ends in a de Sitter regime with a constant asymptotic $Λ$, but vanishing $G$. Although there is no divergence of the scale factor in finite time, such as in the "Big Rip" scenario, gravitationally bound systems eventually become unbound. In the case of systems bound by non-gravitational forces, there is no unbounding effect, as the asymptotic $Λ$ is insufficiently large to disturb these systems.

v1: 12 pages, 4 figures. v2: minor changes in the text, references added. v3: 13 pages, 4 figures, several paragraphs and references added, comparison with the observational bounds introduced. To appear in Phys. Lett. B