Presentation description

The ΛCDM model features a cosmological constant (Λ) associated with the negative pressure of dark energy that drives the expansion of the universe. It is the current standard model of Big Bang cosmology, as it is the simplest model that accounts for many of the large-scale structures we observe in the universe and has successfully explained a broad collection of astronomical measurements over decades. However, recent measurements from DESI (Dark Energy Spectroscopic Instrument), which probes the effects of dark energy through Baryon Acoustic Oscillation (BAO) observations, suggest evidence for dynamics beyond a simple cosmological constant, favoring a time-dependent equation of state. This project examines a scalar field dark energy model in which the energy density in a new scalar field leads to a contribution Ωɸ, to the total energy density of the universe. Different values of Ωɸ and different values for the scalar mass are analyzed in terms of their effect on the expansion history, relative to ΛCDM. We calculate our model's Hubble rate and transverse distances and compare them to the observational data to assess whether this scalar field model represents an improvement relative to ΛCDM. Ultimately, this method provides a framework that can be adapted for analyzing more complex models of dynamical dark energy, potentially leading us to rethink the composition and dynamics of the universe as new data become available.