Constraints on quintessence scalar field models using cosmological observations

TL;DR

This study tests various quintessence scalar field models against multiple cosmological observations, finding they are largely unconstrained and prefer the standard Lambda-CDM model, with limited ability to resolve the H0 tension.

Contribution

It provides a comprehensive observational constraint analysis on quintessence models, showing their parameters are unconstrained and that Lambda-CDM remains the preferred model.

Findings

Scalar field models can transition from deceleration to acceleration.

Observational data do not constrain scalar field parameters.

Lambda-CDM is statistically preferred over quintessence models.

Abstract

We consider a varieties of quintessence scalar field models in a homogeneous and isotropic geometry of the universe with zero spatial curvature aiming to provide stringent constraints using a series of cosmological data sets, namely, the cosmic microwave background observations (CMB), baryon acoustic oscillations (BAO), joint light curve analysis (JLA) from supernovae type Ia, redshift space distortions (RSD), and the cosmic chronometers (CC). From the qualitative evolution of the models, we find all of them are able to execute a fine transition from the past decelerating phase to the presently accelerating expansion where in addition, the equation of state of the scalar field (also the effective equation of state) might be close to that of the $\Lambda$CDM cosmology depending on its free parameters. From the observational analyses, we find that the scalar field parameters are unconstrained irrespective of all the observational datasets. In fact, we find that the quintessence scalar field models are pretty much determined by the CMB observations since any of the external datasets such as BAO, JLA, RSD, CC does not add any constraining power to CMB. Additionally, we observe a strong negative correlation between the parameters $H_0$ (present value of the Hubble parameter), $\Omega_{m0}$ (density parameter for the matter sector, i.e., cold dark matter plus baryons) exists, while no correlation between $H_0$, and $\sigma_8$ (amplitude of the matter fluctuation) are not correlated. We also comment that the present models are unable to reconcile the tension on $H_0$. Finally, we conclude our work with the Bayesian analyses which report that the non-interacting $\Lambda$CDM model is preferred over all the quintessence scalar field models.