The observational constraints on the flat CDM models

Area of Science:

• Cosmology
• Astrophysics
• Particle Physics

Background:

• Most dark energy models converge to the Lambda Cold Dark Matter (ΛCDM) model in certain limits.
• Distinguishing between dark energy models near ΛCDM requires robust statistical methods.

Purpose of the Study:

• To evaluate quintessence and phantom dark energy models against observational data.
• To assess the performance of the ΛCDM model as a baseline.
• To investigate the CPL parametrization's accuracy for scalar field dark energy models.

Main Methods:

• Utilized Monte Carlo Markov Chains to sample posterior likelihood surfaces.
• Employed Fisher information matrix techniques for covariance estimation.
• Compared models using Bayes factors with simulated Dark Energy Spectroscopic Instrument (DESI) survey data.

Main Results:

• The Bayes factor provided substantial evidence favoring the ΛCDM model over most alternative dark energy models.
• Identified the positions of various scalar field dark energy models within the CPL parameter space.

Conclusions:

• The ΛCDM model remains strongly supported by current and projected observational data.
• The CPL parametrization can approximate various scalar field dark energy models, but their specific locations are model-dependent.