The matter with(in) CPL
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arXiv
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| Hauptverfasser: | , , |
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| Format: | Preprint |
| Veröffentlicht: |
2025
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| _version_ | 1866915415799627776 |
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| author | Giani, Leonardo Von Marttens, Rodrigo Piattella, Oliver Fabio |
| author_facet | Giani, Leonardo Von Marttens, Rodrigo Piattella, Oliver Fabio |
| contents | We introduce a two-parameter phenomenological extension of the $Λ$CDM model in which the equation of state parameter of the ``dust'' fluid becomes different from zero for redshifts below a transition value $z_t$. Using data from DESI DR2 BAO, DESY5 Sn~Ia and CMB distance priors ($R,l_A,ω_b$) data, we compare our model with the standard CPL parameterization $w_0-w_a$ for dynamical dark energy. Using the Deviance Information Criteria (DIC), we find that the two models are essentially indistinguishable ($Δ$DIC $<$ 2) and preferred over $Λ$CDM with a significance $\geq 3 σ$. We discuss how this parameterization finds a natural interpretation in the context of cosmological backreaction and derive a prediction for the evolution of the growth factor, discussing its impact on low redshift $fσ_8$ measurements. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_08467 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The matter with(in) CPL Giani, Leonardo Von Marttens, Rodrigo Piattella, Oliver Fabio Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology We introduce a two-parameter phenomenological extension of the $Λ$CDM model in which the equation of state parameter of the ``dust'' fluid becomes different from zero for redshifts below a transition value $z_t$. Using data from DESI DR2 BAO, DESY5 Sn~Ia and CMB distance priors ($R,l_A,ω_b$) data, we compare our model with the standard CPL parameterization $w_0-w_a$ for dynamical dark energy. Using the Deviance Information Criteria (DIC), we find that the two models are essentially indistinguishable ($Δ$DIC $<$ 2) and preferred over $Λ$CDM with a significance $\geq 3 σ$. We discuss how this parameterization finds a natural interpretation in the context of cosmological backreaction and derive a prediction for the evolution of the growth factor, discussing its impact on low redshift $fσ_8$ measurements. |
| title | The matter with(in) CPL |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2505.08467 |