Interpreting DESI 2024 BAO: Late-time dynamical dark energy or a local effect?
Ioannis D. Gialamas, Gert Hütsi, Kristjan Kannike, Antonio Racioppi, M. Raidal, Martin Vasar, Hardi Veermäe
Abstract
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 parametrization $w={w}_{0}+(1\ensuremath{-}a){w}_{a}$ can, misleadingly, hint for a phantom Universe, although quintessence models fit the data well. Model-independently, we find that deviations from $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ are driven by low-$z$ supernova data and take place only at very low redshifts $z<0.1$. Therefore, either our Universe underwent dramatic changes very recently or we do not fully understand our local Universe in a radius of about $300\text{ }\text{ }{h}^{\ensuremath{-}1}\text{ }\mathrm{Mpc}$.