Generalized dark gravity

TL;DR

This paper explores a maximal extension of General Relativity with infra-red modifications, leading to non-geodesic motion and potential observable differences in cosmology, gravitational collapse, and gravitational wave generation.

Contribution

It introduces a generalized dark gravity model extending the Hilbert-Einstein action and analyzes its unique features and potential observational signatures.

Findings

Motion is generally non-geodesic with an orthogonal extra force.

Models predict differences from standard GR in cosmology and gravitational phenomena.

Potential signatures could distinguish this theory from other gravity models.

Abstract

The late-time cosmic acceleration may be due to infra-red modifications of General Relativity. In particular, we consider a maximal extension of the Hilbert-Einstein action and analyze several interesting features of the theory. Generally, the motion is non-geodesic and takes place in the presence of an extra force, which is orthogonal to the four-velocity. These models could lead to some major differences, as compared to the predictions of General Relativity or other modified theories of gravity, in several problems of current interest, such as cosmology, gravitational collapse or the generation of gravitational waves. The study of these phenomena may also provide some specific signatures and effects, which could distinguish and discriminate between the various gravitational models.