$\Lambda_{\rm s}$CDM cosmology from a type-II minimally modified gravity
2024
Online
report
We have successfully integrated $\Lambda_{\rm s}$CDM, a promising model for alleviating cosmological tensions, into a theoretical framework by endowing it with a specific Lagrangian from the VCDM model, a type-II minimally modified gravity. In this theory, we demonstrate that an auxiliary scalar field with a linear potential induces an effective cosmological constant, enabling the realization of an abrupt mirror AdS-dS transition in the late universe through a piecewise linear potential. To eliminate the sudden singularity in this setup and ensure stable transitions, we smooth out this potential. Realized within the VCDM theory, the $\Lambda_{\rm s}$CDM model facilitates two types of rapid smooth mirror AdS-dS transitions: (i) the agitated transition, associated with a smooth jump in the potential, where $\Lambda_{\rm s}$, and consequently $H$, exhibits a bump around the transition's midpoint; and (ii) the quiescent transition, associated with a smooth change in the slope of the potential, where $\Lambda_{\rm s}$ transitions gracefully. These transitions are likely to leave distinct imprints on the background and perturbation dynamics, potentially allowing the observational data to distinguish between them. This novel theoretical framework propels $\Lambda_{\rm s}$CDM into a fully predictive model capable of exploring the evolution of the Universe including the late-time AdS-dS transition epoch, and extends the applicability of the model. We believe further research is crucial in establishing $\Lambda_{\rm s}$CDM as a leading candidate or guide for a new concordance cosmological model.
Comment: 9 pages (including appendices), 4 figures, and no tables
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$\Lambda_{\rm s}$CDM cosmology from a type-II minimally modified gravity
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Autor/in / Beteiligte Person: | Akarsu, Ozgur ; De Felice, Antonio ; Di Valentino, Eleonora ; Kumar, Suresh ; Nunes, Rafael C. ; Ozulker, Emre ; Vazquez, J. Alberto ; Yadav, Anita |
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Veröffentlichung: | 2024 |
Medientyp: | report |
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