# Cosmological perfect fluids in Gauss-Bonnet gravity

## TL;DR

This paper demonstrates that in higher-dimensional Gauss-Bonnet gravity, the modified theories can be equivalently described as perfect fluids, providing a geometric interpretation of dark energy components in cosmology.

## Contribution

It establishes a rigorous link between $f(R,\mathcal{G})$ gravity theories and perfect-fluid descriptions in an $n$-dimensional FRW universe, offering new insights into dark energy modeling.

## Key findings

- Any $f(R,\mathcal{G})$ theory can be associated with a perfect-fluid stress-energy tensor.
- Dark components of the Hubble flow can be interpreted geometrically.
- Provides a framework for understanding dark energy in modified gravity theories.

## Abstract

In an $n$-dimensional Friedmann-Robertson-Walker metric, it is rigorously shown that any analytical theory of gravity $f(R,{\cal G})$, where $R$ is the curvature scalar and $\cal G$ is the Gauss-Bonnet topological invariant, can be associated to a perfect-fluid stress-energy tensor. In this perspective, dark components of the cosmological Hubble flow can be geometrically interpreted.