New non-singular cosmological solution of non-local gravity

TL;DR

This paper introduces a novel bouncing cosmological solution within non-local infinite derivative gravity, demonstrating that such models can produce non-singular bounces with physically reasonable matter content, unlike local gravity theories.

Contribution

The authors develop a new non-singular bouncing cosmological solution in infinite derivative gravity that goes beyond previous recursive ansatz methods, showing its viability with physically acceptable matter.

Findings

The solution is sourced by a perfect fluid with non-negative energy density.

The bouncing behavior cannot be achieved in local gravity theories like GR or R+R^2 with similar matter conditions.

The non-local form-factor critically influences the energy-momentum tensor and the resulting cosmology.

Abstract

We present a new bouncing cosmological solution of the non-local theory known as infinite derivative gravity, which goes beyond the recursive ansatz, ${\Box R = r_1 R +r_2}$. The non-local field equations are evaluated using the spectral decomposition with respect to the eigenfunctions of the wave operator. The energy-momentum tensor computed for this geometry turns out to be much more sensitive to the choice of the non-local form-factor, since it depends on the value of the function on a continuous infinite interval. We show that this stronger dependence on the form-factor allows us to source the geometry by the perfect fluid with the non-negative energy density satisfying the strong energy condition. We show that this bouncing behaviour is not possible in the local theories of gravity such as in general relativity or $R+R^2$ gravity sourced by a fluid which meets the non-negative energy and strong energy conditions.