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Peer-reviewedCC BYPhysical review. D/Physical review. D.

One-parameter dynamical dark energy: Hints for oscillations

  • Anonymous1
  • Luis A. Escamilla2,1
  • Supriya Pan3,4
  • Eleonora Di Valentino1
4 affiliations
  1. 1University of Sheffield
  2. 2Istanbul Technical University
  3. 3Durban University of Technology
  4. 4Presidency University
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Abstract

There is mounting evidence from multiple cosmological probes that dark energy may be dynamical, with an equation of state that evolves over cosmic time. While this evidence is typically quantified using the Chevallier-Polarski-Linder (CPL) parametrization, based on a linear expansion of w ( a ) in the scale factor, nonparametric reconstructions frequently suggest nonlinear features, particularly at late times. In this work, we investigate four minimal one-parameter models of dark energy with nonlinear dependence on the scale factor. These models are constrained using cosmic microwave background data from , lensing reconstruction from and ACT-DR6, baryon acoustic oscillation measurements from DESI-DR2, and three type Ia supernovae (SNe) samples (PantheonPlus, DESY5, and Union3), considered independently. Although our conclusions depend on the choice of SNe sample, we consistently find a preference, as measured by the chi-squared statistic and the Bayesian evidence, for these dynamical dark energy models over the standard Λ CDM (cold dark matter) model. Notably, with the PantheonPlus dataset, one model shows strong Bayesian evidence ( Δ ln B ≃ 4.5 ) over CPL, favoring an equation of state that peaks near a ≃ 0.7 and oscillates near the present day. These results highlight the impact of SNe selection and contribute to the growing collection of evidence for late-time deviations from Λ CDM .

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Cite

BibTeXRIS
BibTeX
@article{anonymous2026oneparameter,
  title = {{One-parameter dynamical dark energy: Hints for oscillations}},
  author = {Anonymous and Luis A. Escamilla and Supriya Pan and Eleonora Di Valentino},
  journal = {Physical review. D/Physical review. D.},
  year = {2026},
  month = jul,
  doi = {10.1103/1x6w-4tnd},
  url = {https://doi.org/10.1103/1x6w-4tnd},
  note = {CC BY},
}
RIS
TY  - JOUR
TI  - One-parameter dynamical dark energy: Hints for oscillations
AU  - Anonymous
AU  - Luis A. Escamilla
AU  - Supriya Pan
AU  - Eleonora Di Valentino
PY  - 2026
DA  - 2026/07/31
JO  - Physical review. D/Physical review. D.
DO  - 10.1103/1x6w-4tnd
UR  - https://doi.org/10.1103/1x6w-4tnd
AB  - There is mounting evidence from multiple cosmological probes that dark energy may be dynamical, with an equation of state that evolves over cosmic time. While this evidence is typically quantified using the Chevallier-Polarski-Linder (CPL) parametrization, based on a linear expansion of w ( a ) in the scale factor, nonparametric reconstructions frequently suggest nonlinear features, particularly at late times. In this work, we investigate four minimal one-parameter models of dark energy with nonlinear dependence on the scale factor. These models are constrained using cosmic microwave background data from , lensing reconstruction from and ACT-DR6, baryon acoustic oscillation measurements from DESI-DR2, and three type Ia supernovae (SNe) samples (PantheonPlus, DESY5, and Union3), considered independently. Although our conclusions depend on the choice of SNe sample, we consistently find a preference, as measured by the chi-squared statistic and the Bayesian evidence, for these dynamical dark energy models over the standard Λ CDM (cold dark matter) model. Notably, with the PantheonPlus dataset, one model shows strong Bayesian evidence ( Δ ln B ≃ 4.5 ) over CPL, favoring an equation of state that peaks near a ≃ 0.7 and oscillates near the present day. These results highlight the impact of SNe selection and contribute to the growing collection of evidence for late-time deviations from Λ CDM .
SN  - 2470-0010
SN  - 2470-0029
SN  - 2470-0037
ER  -