# Is the cosmological dark sector better modeled by a generalized Chaplygin gas or by a scalar field?

## TL;DR

This paper compares scalar fields and generalized Chaplygin gases as models for the universe's dark sector, analyzing their background dynamics, observational consistency, and impact on matter perturbations.

## Contribution

It investigates a combined dark sector model with both components, assessing observational viability and perturbation effects, which is a novel approach.

## Key findings

- Both models can fit supernova and Hubble data
- Dark-sector perturbations influence matter growth rates
- Fractional abundances vary with observational constraints

## Abstract

Both scalar fields and (generalized) Chaplygin gases have been widely used separately to characterize the dark sector of the Universe. Here we investigate the cosmological background dynamics for a mixture of both these components and quantify the fractional abundances that are admitted by observational data from supernovae of type Ia and from the evolution of the Hubble rate. Moreover, we study how the growth rate of (baryonic) matter perturbations is affected by the dark-sector perturbations.