Back-Reaction of Super-Hubble Fluctuations, Late Time Tracking and Recent Observational Results
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| Format: | Preprint |
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2025
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| _version_ | 1866915341131579392 |
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| author | Alvarez, Marco Antonio Cardoso Graef, Leila Brandenberger, Robert |
| author_facet | Alvarez, Marco Antonio Cardoso Graef, Leila Brandenberger, Robert |
| contents | Previous studies suggested that the back-reaction of super-Hubble cosmological fluctuations could lead to a dynamical relaxation of the cosmological constant. Moreover, this mechanism appears to be self-regulatory, potentially leading to an oscillatory behavior in the effective dark energy. Such an effect would occur in any cosmological model with super-Hubble matter fluctuations, including the standard $Λ\text{CDM}$ model. The recent DESI data, which indicate that dark energy may be dynamical, has renewed interest in exploring scenarios leading to such oscillatory behavior. In this work we propose a parametrization to account for the impact of super-Hubble fluctuations on the background energy density of the Universe. We model the total effective cosmological constant as the sum of a constant piece and an oscillating contribution. We perform a preliminary comparison of the background dynamics of this model with the recent radial BAO data from DESI. We also discuss the status of the $H_0$ tension problem in this model. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_17395 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Back-Reaction of Super-Hubble Fluctuations, Late Time Tracking and Recent Observational Results Alvarez, Marco Antonio Cardoso Graef, Leila Brandenberger, Robert Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory Previous studies suggested that the back-reaction of super-Hubble cosmological fluctuations could lead to a dynamical relaxation of the cosmological constant. Moreover, this mechanism appears to be self-regulatory, potentially leading to an oscillatory behavior in the effective dark energy. Such an effect would occur in any cosmological model with super-Hubble matter fluctuations, including the standard $Λ\text{CDM}$ model. The recent DESI data, which indicate that dark energy may be dynamical, has renewed interest in exploring scenarios leading to such oscillatory behavior. In this work we propose a parametrization to account for the impact of super-Hubble fluctuations on the background energy density of the Universe. We model the total effective cosmological constant as the sum of a constant piece and an oscillating contribution. We perform a preliminary comparison of the background dynamics of this model with the recent radial BAO data from DESI. We also discuss the status of the $H_0$ tension problem in this model. |
| title | Back-Reaction of Super-Hubble Fluctuations, Late Time Tracking and Recent Observational Results |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2502.17395 |