Investigation shows dark energy influences cosmic evolution using Markov Chain Monte Carlo methods, pointing to a potential big rip.
I investigate a dynamical dark energy model based on a generalised logarithmic equation of state, derived from a canonical scalar field Lagrangian and extending the Ma-Zhang parametrisation via two parameters [Formula: see text]. Fixing [Formula: see text], I compute the cosmic time-redshift relation [Formula: see text] by numerically evaluating the integral [Formula: see text], where [Formula: see text] follows from the Friedmann equation and a redshift-dependent [Formula: see text]. I reconstruct the scalar field dynamics [Formula: see text] and potential [Formula: see text] corresponding to this phenomenological input, and calculate the evolution of key cosmological quantities including [Formula: see text], [Formula: see text], and [Formula: see text]. Using Markov Chain Monte Carlo (MCMC) sampling, I constrain the model against observational data for [Formula: see text], recovering posterior distributions for [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. I further analyse the onset of future singularities and the coincidence problem, noting that the current age of the universe may lie near the midpoint to a big rip. Perturbative stability is confirmed within the parameter space considered. The framework provides a flexible and physically consistent approach to modelling evolving dark energy within a scalar field theory.
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Bram Hennekes (2025) studied this question.
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