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| Main Authors: | , , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2605.18240 |
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| _version_ | 1866917507978231808 |
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| author | Mohammadi, Sahar Yusofi, Ebrahim Asadi, Kosar |
| author_facet | Mohammadi, Sahar Yusofi, Ebrahim Asadi, Kosar |
| contents | We present a comprehensive phase-space analysis of a quadratic dark energy model where the pressure includes a nonlinear term proportional to the square of the energy density. This minimal extension beyond the $Λ$CDM framework introduces a dynamical parameter $η(z)$ that governs transitions between different cosmological regimes. Through dynamical systems theory, we identify critical points and their stability properties, revealing that negative $η$ values drive the system toward stable phantom attractors (sinks), while positive values correspond to unstable repellers (sources). The model exhibits a distinctive asymptotic approach to the phantom divide ($w_{\rm eff}=-1$) from both quintessence and phantom sides without actual crossing, providing a non-crossing alternative to the phantom-crossing behavior preferred by recent DESI DR2 constraints. Our analysis shows that stable phantom attractors produce enhanced Hubble expansion rates and more pronounced late-time acceleration, features that can be compared with recent DESI observations suggesting evolving dark energy. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_18240 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Quadratic Dark Energy Phase-Space Dynamics and Analysis Mohammadi, Sahar Yusofi, Ebrahim Asadi, Kosar Cosmology and Nongalactic Astrophysics We present a comprehensive phase-space analysis of a quadratic dark energy model where the pressure includes a nonlinear term proportional to the square of the energy density. This minimal extension beyond the $Λ$CDM framework introduces a dynamical parameter $η(z)$ that governs transitions between different cosmological regimes. Through dynamical systems theory, we identify critical points and their stability properties, revealing that negative $η$ values drive the system toward stable phantom attractors (sinks), while positive values correspond to unstable repellers (sources). The model exhibits a distinctive asymptotic approach to the phantom divide ($w_{\rm eff}=-1$) from both quintessence and phantom sides without actual crossing, providing a non-crossing alternative to the phantom-crossing behavior preferred by recent DESI DR2 constraints. Our analysis shows that stable phantom attractors produce enhanced Hubble expansion rates and more pronounced late-time acceleration, features that can be compared with recent DESI observations suggesting evolving dark energy. |
| title | Quadratic Dark Energy Phase-Space Dynamics and Analysis |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2605.18240 |