Interpreting DESI 2024 BAO: late-time dynamical dark energy or a local effect?

Understand

We perform fits to DESI, CMB and supernova data to understand the physical origin of the DESI hint for dynamical dark energy.

• We find that the linear parametrization of the equation of state $w$ may guide to misleading interpretations, such as the hint for a phantom Universe, which are not preferred by the data.
• Instead, physical quintessence models fit the data well.
• Model-independently, present observations prefer deviations from the constant dark energy, $w=-1$, only at very low redshifts, $z < \mathcal{O}(0.1)$.