Dynamical dark energy in models with evolution close to $Λ$CDM
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| Format: | Preprint |
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2025
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| _version_ | 1866918185605791744 |
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| author | Chakraborty, Saikat Louw, Charlotte Dunsby, Peter K. S. MacDevette, Kelly Dombriz, Alvaro de la Cruz |
| author_facet | Chakraborty, Saikat Louw, Charlotte Dunsby, Peter K. S. MacDevette, Kelly Dombriz, Alvaro de la Cruz |
| contents | In this communication we address whether or not there is an equivalence between the kinematical and dynamical descriptions of the spatially flat $Λ$CDM model. We address this by investigating whether an almost $Λ$CDM expansion history ($j(z)\approx1$) corresponds to an almost $Λ$CDM model ($w_{\rm DE}(z)\approx-1$) by considering two particular explicit examples. At least for the cases considered, this turns out not to be the case. Instead, what we find is that an almost $Λ$CDM cosmic evolution rather corresponds to an \emph{almost unified dark fluid model}. Considering that one never gets the exact condition $j(z)=1$ from any cosmographic data sets, this raises further questions on whether the $Λ$CDM model is the best candidate for the standard model of the evolution of the universe. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2508_09813 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Dynamical dark energy in models with evolution close to $Λ$CDM Chakraborty, Saikat Louw, Charlotte Dunsby, Peter K. S. MacDevette, Kelly Dombriz, Alvaro de la Cruz General Relativity and Quantum Cosmology In this communication we address whether or not there is an equivalence between the kinematical and dynamical descriptions of the spatially flat $Λ$CDM model. We address this by investigating whether an almost $Λ$CDM expansion history ($j(z)\approx1$) corresponds to an almost $Λ$CDM model ($w_{\rm DE}(z)\approx-1$) by considering two particular explicit examples. At least for the cases considered, this turns out not to be the case. Instead, what we find is that an almost $Λ$CDM cosmic evolution rather corresponds to an \emph{almost unified dark fluid model}. Considering that one never gets the exact condition $j(z)=1$ from any cosmographic data sets, this raises further questions on whether the $Λ$CDM model is the best candidate for the standard model of the evolution of the universe. |
| title | Dynamical dark energy in models with evolution close to $Λ$CDM |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2508.09813 |