Reconstruction, Analysis and Constraints of Cosmological Scalar Field <i>ϕ</i>CDM Models

Abstract

We studied the following scalar field ϕCDM models: ten quintessence models and seven phantom models. We reconstructed these models using the phenomenological method developed by our group. For each potential, the following ranges were found: (i) model parameters; (ii) EoS parameters; and (iii) the initial conditions for differential equations, which describe the dynamics of the universe. Using MCMC analysis, we obtained the constraints of scalar field models by comparing observations for the expansion rate of the universe, the angular diameter distance and the growth rate function, with corresponding data generated for the fiducial ΛCDM model. We applied Bayes statistical criteria to compare scalar field models. To this end, we calculated the Bayes factor, as well as the AIC and BIC information criteria. The results of this analysis show that we could not uniquely identify the preferable scalar field ϕCDM models compared to the fiducial ΛCDM model based on the predicted DESI data, and that the ΛCDM model is a true dark energy model. We investigated scalar field ϕCDM models in the w0–wa phase spaces of the CPL-ΛCDM contours. We identified subclasses of quintessence and phantom scalar field models that, in the present epoch: (i) can be distinguished from the ΛCDM model; (ii) cannot be distinguished from the ΛCDM model; and (iii) can be either distinguished or undistinguished from the ΛCDM model. We found that all the studied models can be divided into two classes: models that have attractor solutions and models whose evolution depends on initial conditions.

Keywords

• dark energy
• scalar field
• large-scale structure
• Bayesian statistics
• Monte Carlo Markov chain analysis