Inevitable manifestation of wiggles in the expansion of the late Universe

Özgür Akarsu, Eoin Colgáin, Emre Özülker, Somyadip Thakur, Lu Yin

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8 Citations (Scopus)


Using the fact that the comoving angular diameter distance to the last scattering surface is strictly constrained almost model independently, we show that, for any model agreeing with the standard ΛCDM model on its background dynamics at z∼0 and size of the comoving sound horizon at last scattering, the deviations of the Hubble radius from the one of the standard ΛCDM model must be a member of the set of admissible wavelets. The family of models characterized by this framework also offers nontrivial oscillatory behaviors in various functions that define the kinematics of the Universe, even when the wavelets themselves are very simple. We also discuss the consequences of attributing these kinematics to, first, dark energy, and second, varying gravitational coupling strength. Utilizing some simplest wavelets, we demonstrate the competence of this framework in describing the baryon acoustic oscillation (BAO) data without any modifications to the agreement with cosmic microwave background measurements. This framework also provides a natural explanation for the bumps found in nonparametric observational reconstructions of the Hubble parameter and dark energy density as compensations of the dips suggested by some BAO data, and questions the physical reality of their existence. We note that utilizing this framework on top of the models that agree with both the cosmic microwave background and local H0 measurements but are held back by BAO data, one may resurrect these models through the wiggly nature of wavelets that can naturally accommodate the BAO data. Finally, we also suggest narrowing the plausible set of admissible wavelets to further improve our framework by imposing conditions from expected kinematics of a viable cosmological model or first principle fundamental physics such as energy conditions.

Original languageEnglish
Article number123526
JournalPhysical Review D
Issue number12
Publication statusPublished - 15 Jun 2023

Bibliographical note

Publisher Copyright:
© 2023 American Physical Society.


The authors thank to Bum-Hoon Lee and Kazuya Koyama for useful insights and discussions. Ö. A. acknowledges the support by the Turkish Academy of Sciences in the scheme of the Outstanding Young Scientist Award (TÜBA-GEBİP). E. Ó. C. was supported by the National Research Foundation of Korea grant funded by the Korea government (MSIT) (NRF-2020R1A2C1102899). E. Ö. acknowledges the support by The Scientific and Technological Research Council of Turkey (TÜBİTAK) in the scheme of 2211/A National Phd Scholarship Program. S. T. and L. Y. were supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education through the Center for Quantum Spacetime (CQUeST) of Sogang University (NRF-2020R1A6A1A03047877). L. Y. also thanks the support from YST project in APCTP.

FundersFunder number
Center for Quantum Spacetime
Sogang UniversityNRF-2020R1A6A1A03047877
Ministry of Science, ICT and Future PlanningNRF-2020R1A2C1102899
National Research Foundation of Korea
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu
Türkiye Bilimler Akademisi
Milli Eğitim Bakanliği


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