A Dark Matter Model with Quadratic Equation of State: Background Evolution and Structure Formation
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| Format: | Preprint |
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2025
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| _version_ | 1866908680485601280 |
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| author | Rezazadeh, Kazem Yusofi, Ebrahim Talebian, Alireza |
| author_facet | Rezazadeh, Kazem Yusofi, Ebrahim Talebian, Alireza |
| contents | We propose that dark matter (DM) possesses a quadratic equation of state, which becomes significant at high densities, altering the Universe's evolution during its early stages. We derive the modified background evolution equations for the Hubble parameter $H(z)$ and the DM density parameter $Ω_{\text{dm}}(z)$. We then perturb the governing equations to study the linear growth of matter fluctuations, computing the observable growth factor $fσ_8(z)$. Finally, we compare the model with the latest cosmological data, including Hubble parameter $H(z)$ measurements, and growth factor $fσ_8(z)$ data, up to $z=3$. Our results indicate that the quadratic model, while remaining consistent with background observations, offers a distinct imprint on the growth of structure, providing not only a new phenomenological avenue to address cosmological tensions but also shedding light on the nature of DM. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_11138 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A Dark Matter Model with Quadratic Equation of State: Background Evolution and Structure Formation Rezazadeh, Kazem Yusofi, Ebrahim Talebian, Alireza Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology High Energy Physics - Phenomenology We propose that dark matter (DM) possesses a quadratic equation of state, which becomes significant at high densities, altering the Universe's evolution during its early stages. We derive the modified background evolution equations for the Hubble parameter $H(z)$ and the DM density parameter $Ω_{\text{dm}}(z)$. We then perturb the governing equations to study the linear growth of matter fluctuations, computing the observable growth factor $fσ_8(z)$. Finally, we compare the model with the latest cosmological data, including Hubble parameter $H(z)$ measurements, and growth factor $fσ_8(z)$ data, up to $z=3$. Our results indicate that the quadratic model, while remaining consistent with background observations, offers a distinct imprint on the growth of structure, providing not only a new phenomenological avenue to address cosmological tensions but also shedding light on the nature of DM. |
| title | A Dark Matter Model with Quadratic Equation of State: Background Evolution and Structure Formation |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2509.11138 |