DESI Constraints on Exponential Quintessence

Abstract

The DESI collaboration have recently analyzed their first year of data, finding a preference for thawing dark energy scenarios when using parameterized equations of state for dark energy. We investigate whether this preference persists when the data is analyzed within the context of a well-studied field theory model of thawing dark energy, exponential quintessence. No preference for this model over $\Lambda$CDM is found, and both models are poorer fits to the data than the Chevallier-Polarski-Linder $w_0$--$w_a$ parameterization. We demonstrate that the worse fit is due to a lack of sharp features in the potential that results in a slowly-evolving dark energy equation of state that does not have enough freedom to simultaneously fit the combination of the supernovae, DESI, and cosmic microwave background data. Our analysis provides guidance for constructing dynamical dark energy models that are able to better accommodate the data.