A novel approach to cosmological non-linearities as an effective fluid
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866908442616135680 |
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| author | Giani, Leonardo Von Marttens, Rodrigo Camilleri, Ryan |
| author_facet | Giani, Leonardo Von Marttens, Rodrigo Camilleri, Ryan |
| contents | We propose a two parameters extension of the flat $Λ$CDM model to capture the impact of matter inhomogeneities on our cosmological inference. Non virialized but non-linearly evolving overdense and underdense regions, whose abundance is quantified using the Press-Schechter formalism, are collectively described by two effective perfect fluids $ρ_{\rm{c}},ρ_{\rm{v}}$ with non vanishing equation of state parameters $w_{\rm{c,v}}\neq 0$. These fluids are coupled to the pressureless dust, akin to an interacting DM-DE scenario. The resulting phenomenology is very rich, and could potentially address a number of inconsistencies of the standard model, including a simultaneous resolution of the Hubble and $σ_8$ tensions. To assess the viability of the model, we set initial conditions compatible to the Planck 2018 best fit $Λ$CDM cosmology and fit its additional parameters using SN~Ia observations from DESY5, BAO distances from DESI DR2 and a sample of uncorrelated $fσ_8$ measurements. Our findings show that backreaction effects from the cosmic web could restore the concordance between early and late Universe cosmological probes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_15295 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | A novel approach to cosmological non-linearities as an effective fluid Giani, Leonardo Von Marttens, Rodrigo Camilleri, Ryan Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology We propose a two parameters extension of the flat $Λ$CDM model to capture the impact of matter inhomogeneities on our cosmological inference. Non virialized but non-linearly evolving overdense and underdense regions, whose abundance is quantified using the Press-Schechter formalism, are collectively described by two effective perfect fluids $ρ_{\rm{c}},ρ_{\rm{v}}$ with non vanishing equation of state parameters $w_{\rm{c,v}}\neq 0$. These fluids are coupled to the pressureless dust, akin to an interacting DM-DE scenario. The resulting phenomenology is very rich, and could potentially address a number of inconsistencies of the standard model, including a simultaneous resolution of the Hubble and $σ_8$ tensions. To assess the viability of the model, we set initial conditions compatible to the Planck 2018 best fit $Λ$CDM cosmology and fit its additional parameters using SN~Ia observations from DESY5, BAO distances from DESI DR2 and a sample of uncorrelated $fσ_8$ measurements. Our findings show that backreaction effects from the cosmic web could restore the concordance between early and late Universe cosmological probes. |
| title | A novel approach to cosmological non-linearities as an effective fluid |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2410.15295 |