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arXiv · 2609.40176

Is DESI Seeing Dynamical Dark Energy, or a Cosmic Glitch in Gravity?

Robin Y. Wen·Lukas Tobias Hergt·Niayesh Afshordi·Douglas Scott
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Abstract

Combined baryon acoustic oscillation and cosmic microwave background data have begun to mildly favor departures from $Λ\mathrm{CDM}$. This is usually framed as 2-parameter dynamical dark energy. However, a 1-parameter "cosmic glitch in gravity" model, whose cosmological gravitational coupling differs from Newton's constant as in Hořava gravity, fits at least as well. $\textit{Planck}$+ACT+SPT and DESI~DR2 give $G_\mathrm{cosmo}/G_\mathrm{N}=0.9920\pm0.0025$, a $3.3\,σ$ preference for weaker cosmological gravity, robust to adding CMB lensing and supernovae. Fitted to the CMB alone, the glitch predicts DESI distances; $w_0w_a$CDM does not.

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Robin Y. Wen, Lukas Tobias Hergt, Niayesh Afshordi, Douglas Scott. 2026-09-30. Is DESI Seeing Dynamical Dark Energy, or a Cosmic Glitch in Gravity?. https://arxiv.org/abs/2609.40176

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