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arXiv · 2606.24221

Late-Time Oscillating Quintessence in Light of DESI

Jun-Qian Jiang·Mustafa A. Amin·Arman Shafieloo
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Abstract

Recent DESI baryon acoustic oscillation measurements, especially when combined with Type Ia supernova and CMB data, sharpen the case for possible low-redshift dynamics in the dark energy sector. We study a simple and physically transparent realization of such dynamics: a quintessence field that is Hubble frozen for most of cosmic history and starts to oscillate around its minimum recently (at a redshift $z\approx 0.1$). This late onset of oscillations can occur in a broad class of models where the quintessence potentials have a shallow slope away from the minimum and steepen near it. This class of models can improve the fit relative to $Λ$CDM, with $Δχ^2\simeq -9$, while remaining competitive with common phenomenological dark energy parameterizations with the same number of parameters. The preference is driven mainly by the background expansion history, and near the best-fit region the resonant growth of quintessence perturbations and the associated Integrated Sachs-Wolfe (ISW) contribution remain small. More precise low-redshift distance measurements, together with late-time probes such as the ISW effect and lensing, may help distinguish this oscillating quintessence scenario from other forms of late-time dark energy dynamics.

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Jun-Qian Jiang, Mustafa A. Amin, Arman Shafieloo. 2026-06-23. Late-Time Oscillating Quintessence in Light of DESI. https://arxiv.org/abs/2606.24221

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