DESI 2024: Constraints on Physics-Focused Aspects of Dark Energy using DESI DR1 BAO Data

TL;DR

This paper uses DESI DR1 BAO data combined with other probes to explore and constrain three physically motivated classes of dark energy models, finding they fit the data as well as or better than the standard cosmological constant model.

Contribution

It introduces and tests three novel classes of dark energy models—thawing, emergent, and mirage—showing they can match or outperform ΛCDM in fitting observational data.

Findings

All three dark energy classes fit the data as well as ΛCDM.

Some models improve the fit by Δχ² ≈ -5 to -17 over ΛCDM.

The mirage class performs comparably to w₀wₐCDM with fewer parameters.

Abstract

Baryon acoustic oscillation data from the first year of the Dark Energy Spectroscopic Instrument (DESI) provide near percent-level precision of cosmic distances in seven bins over the redshift range $z=0.1$-$4.2$. We use this data, together with other distance probes, to constrain the cosmic expansion history using some well-motivated physical classes of dark energy. In particular, we explore three physics-focused behaviors of dark energy from the equation of state and energy density perspectives: the thawing class (matching many simple quintessence potentials), emergent class (where dark energy comes into being recently, as in phase transition models), and mirage class (where phenomenologically the distance to CMB last scattering is close to that from a cosmological constant $\Lambda$ despite dark energy dynamics). All three classes fit the data at least as well as $\Lambda$CDM, and indeed can improve on it by $\Delta\chi^2\approx -5$ to $-17$ for the combination of DESI BAO with CMB and supernova data, while having one more parameter. The mirage class does essentially as well as $w_0w_a$CDM while having one less parameter. These classes of dynamical behaviors highlight worthwhile avenues for further exploration into the nature of dark energy.