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arXiv · 2506.02122

Uplifting, Depressing, and Tilting Dark Energy

Eric V. Linder
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Abstract

Current data in the form of baryon acoustic oscillation, supernova, and cosmic microwave background distances prefer a cosmology that accelerates more strongly than $\Lambda$CDM at $z\approx0.5-1.5$, and more weakly at $z\lesssim0.5$. We examine dark energy physics that can accommodate this, showing that interactions (decays, coupling to matter, nonminimal coupling to gravity) fairly generically tend not to give a satisfactory solution (in terms of fitting both distances and growth) even if they enable the effective dark energy equation of state to cross $w=-1$. To fit the cosmological data it appears the dark energy by itself must cross $w=-1$, a highly unusual physical behavior.

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Eric V. Linder. 2025-06-02. Uplifting, Depressing, and Tilting Dark Energy. https://arxiv.org/abs/2506.02122

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