A Dark Energy model combining DGP gravity and Chaplygin gas

TL;DR

This paper proposes a combined dark energy model using DGP gravity and Chaplygin gas, explaining the universe's accelerated expansion with a unified approach that transitions from dust-like behavior to a cosmological constant.

Contribution

It introduces a novel combined model of DGP gravity and Chaplygin gas, deriving and numerically solving the continuity equation to demonstrate its properties.

Findings

The model exhibits dust-like behavior at small scales.

At large scales, it behaves as a cosmological constant.

The combined model increases the present dark energy density.

Abstract

The expansion of the Universe is accelerating, as testified by observations of supernovae of type Ia as a function of redshift. Explanations are of two types: modifications of Einstein gravity or new forms of energy, coined dark energy.The accelerated expansion is explained here by a combination of Dvali-Gabadadze-Porrati (DGP) model gravity and Chaplygin gas dark energy. Both models are characterized by a length scale L which may be the same. The continuity equation for the combined model is derived in flat geometry, and solved by numerical methods. The solution is shown to have the expected properties: at very small scales (a<<L) the energy density behaves as pressureless dust, at very large scales (a>>L) as a cosmological constant. The modifications to the DGP model and the Chaplygin gas model occur for values of a L. The results show an increase in the present dark energy density relative to the plain DGP model.