Simplified Chaplygin Gas: Deriving $H_0$ From Ages of Old High Redshift Objects and Baryon Acoustic Oscillations

TL;DR

This paper investigates simplified Chaplygin gas models as explanations for cosmic acceleration, using old high redshift objects and baryon acoustic oscillations to constrain model parameters and estimate the Hubble constant.

Contribution

It introduces a method combining age estimates of high redshift objects and BAO data to constrain simplified Chaplygin gas models and estimate H_0.

Findings

Old high redshift objects severely constrain the models.

Joint analysis yields estimates for the Hubble constant.

Simplified Chaplygin models can mimic dark energy or unify dark sectors.

Abstract

The discovery that the expansion of the Universe is accelerating is the most challenging problem of modern cosmology. In the context of general relativity, there are many dark energy candidates to explain the observed acceleration. In this work we focus our attention on two kinds of simplified Chaplygin gas cosmological accelerating models recently proposed in the literature. In the first scenario, the simplified Chaplygin gas works like a Quintessence model while in the second one, it plays the role of a Quartessence (an unification of the dark sector). Firstly, in order to limit the free parameters of both models, we discuss the age of high redshift objects with special emphasis to the old quasar APM 08279+5255 at $z = 3.91$. The basic finding is that this old high redshift object constrain severely the simplified Chaplygin cosmologies. Secondly, through a joint analysis involving the baryon acoustic oscillations (BAO) and a sample of old high redshift galaxies (OHRGs) we also estimate the value of the Hubble parameter, $H_0$. Our approach suggests that the combination of these two independent phenomena provides an interesting method to constrain the Hubble constant.