Stability and Thermodynamics of a Generalized Power-Law Dark Energy Model
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| Format: | Preprint |
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2025
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| _version_ | 1866908438124036096 |
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| author | Kazemi, S. Ramzanpour, M. A. Yusofi, E. Amani, A. R. |
| author_facet | Kazemi, S. Ramzanpour, M. A. Yusofi, E. Amani, A. R. |
| contents | We investigate a generalized power-law dark energy equation of state of the form $p = wρ- βρ^m$ in a flat FLRW universe, analyzing its dynamical stability and thermodynamic consistency. The model exhibits a rich phase space structure, with an effective cosmological constant $ρ^* = [(1+w)/β]^{1/(m-1)}$ emerging as a stable attractor for $(w < -1,~ m > 1)$. Notably, the universe evolves from an early de Sitter phase ($w \to -1$) to a late-time de Sitter-like one with phantom crossing ($w(z) < -1$), aligning with DESI observations. Dynamical analysis reveals that the $m > 1$ regime avoids ghost instabilities while accommodating phantom behavior, with $m = 2$ providing particular theoretical advantages. Thermodynamically, the Generalized Second Law holds when the null energy condition $ρ+ p \geq 0$ is satisfied, which naturally occurs for $ρ\geq ρ^*$. The model's compatibility with both observational data and fundamental thermodynamic principles suggests it as a viable framework for describing late-time cosmic acceleration, resolving tensions associated with phantom crossing while maintaining entropy dominance of the cosmological horizon. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_03808 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Stability and Thermodynamics of a Generalized Power-Law Dark Energy Model Kazemi, S. Ramzanpour, M. A. Yusofi, E. Amani, A. R. General Relativity and Quantum Cosmology Cosmology and Nongalactic Astrophysics We investigate a generalized power-law dark energy equation of state of the form $p = wρ- βρ^m$ in a flat FLRW universe, analyzing its dynamical stability and thermodynamic consistency. The model exhibits a rich phase space structure, with an effective cosmological constant $ρ^* = [(1+w)/β]^{1/(m-1)}$ emerging as a stable attractor for $(w < -1,~ m > 1)$. Notably, the universe evolves from an early de Sitter phase ($w \to -1$) to a late-time de Sitter-like one with phantom crossing ($w(z) < -1$), aligning with DESI observations. Dynamical analysis reveals that the $m > 1$ regime avoids ghost instabilities while accommodating phantom behavior, with $m = 2$ providing particular theoretical advantages. Thermodynamically, the Generalized Second Law holds when the null energy condition $ρ+ p \geq 0$ is satisfied, which naturally occurs for $ρ\geq ρ^*$. The model's compatibility with both observational data and fundamental thermodynamic principles suggests it as a viable framework for describing late-time cosmic acceleration, resolving tensions associated with phantom crossing while maintaining entropy dominance of the cosmological horizon. |
| title | Stability and Thermodynamics of a Generalized Power-Law Dark Energy Model |
| topic | General Relativity and Quantum Cosmology Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2507.03808 |