Physical vs phantom dark energy after DESI: thawing quintessence in a curved background

Bikash R. Dinda; Roy Maartens

doi:10.1093/mnrasl/slaf063

paper

Physical vs phantom dark energy after DESI: thawing quintessence in a curved background

arXiv:2504.15190 · doi:10.1093/mnrasl/slaf063

Abstract

Recent data from DESI, in combination with other data, provide moderate evidence of dynamical dark energy, $w \neq = - 1$ . In the $w_{0}, w_{a}$ parametrization of $w$ , there is a preference for a phantom crossing, $w < - 1$ , at redshift $z \sim 0.5$ . In general relativity, the phantom equation of state is unphysical. Thus it is important to check whether phantom crossing is present in other physically self-consistent models of dark energy that have equivalent evidence to the $w_{0}, w_{a}$ parametrization. We find that thawing quintessence with nonzero cosmic curvature can fit the recent data as well as $w_{0}, w_{a}$ in a flat background, based on both parametric and realistic scalar field evolutions. Although the realistic model does not allow $w < - 1$ , the parametrizations do allow it. However even if we allow $w < - 1$ the data do not enforce phantom crossing. Thus, the phantom crossing is an artifact of a parametrization that is not based on a physical model.

Minor changes. Version accepted by MNRAS Letters

Physical vs phantom dark energy after DESI: thawing quintessence in a curved background

Abstract

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