# Primordial bouncing cosmology in the Deser-Woodard nonlocal gravity

## TL;DR

This paper demonstrates how the Deser-Woodard nonlocal gravity model can produce a primordial bounce, avoiding the initial singularity, and shows that anisotropies grow more mildly near the bounce due to nonlocal effects.

## Contribution

It reconstructs a nonlocal distortion function within the DW model to realize a bouncing cosmology, extending its application to early universe scenarios.

## Key findings

- A bouncing solution is achieved in the DW nonlocal gravity model.
- The distortion function and its derivative approach zero after the bounce.
- Anisotropies grow milder near the bounce due to nonlocal effects.

## Abstract

The Deser-Woodard (DW) nonlocal gravity model has been proposed in order to describe the late-time acceleration of the universe without introducing dark energy. In this paper we focus, however, on the early stage of the universe and demonstrate how a primordial bounce in the vacuum spacetime can be realized in the framework of the DW nonlocal model. We reconstruct the nonlocal distortion function, which encodes all the modifications to the Einstein-Hilbert action, in order to generate bouncing solutions to solve the initial singularity problem. We show that the initial conditions can be chosen in such a way that the distortion function and its first order derivative approach zero after the bounce and the standard cosmological solution described by general relativity is recovered afterwards. We also study the evolution of anisotropies near the bounce. It turns out that the shear density defined by the anisotropy grows towards the bounce, but due to the presence of nonlocal effects, it grows in a milder manner compared with that in Einstein gravity.