Can the Universe decelerate in the future?

TL;DR

This study explores whether the universe's expansion could slow down in the future using a quintessence scalar field model, updated observational data, and a model-independent Gaussian Processes approach, finding that future deceleration is plausible.

Contribution

The paper introduces an extended Ratra-Peebles quintessence model with parameters that permit future deceleration, contrasting with the standard de Sitter expansion prediction.

Findings

Extended RP model allows for future deceleration with current data.

Updated analysis yields H_0 = 68.6±3.7 km/s/Mpc.

Gaussian Processes suggest future deceleration only with H(z) data.

Abstract

The possibility of an expanding decelerating Universe in the distant future is investigated in the context of a quintessence scalar field cosmology. Such a conceivable evolution is tested against SNe Ia and $H(z)$ cosmic chronometers data, and also through a model independent method based on Gaussian Processes. The scalar field model is an extension of the exponential Ratra-Peebles (RP) quintessential cosmology whose potential now depends on a pair of parameters ($\alpha, \lambda)$ and predicts a decelerated expansion in the future. Different from RP approach the $\alpha$ parameter allows for a decelerating cosmology in the future thereby frustrating the inevitable evolution for a de Sitter Cosmology as predicted by the cosmic concordance model ($\Lambda$CDM). The statistical model analysis is updated with the most recent SNe Ia and $H(z)$ data thereby obtaining $H_0 = 68.6\pm3.7$ km/s/Mpc, $\Omega_{\Phi0} = 0.735^{+0.083}_{-0.069} $, $\alpha < 6.56$ and $\lambda< 0.879 $ (at $2\sigma$ c.l.). It is also found that the extended RP model allows for a future deceleration both for $H(z)$ and SNe Ia data. In the (model-independent) Gaussian Processes analysis, however, future deceleration is allowed only in the case of $H(z)$ data.