Reconstructing cosmic expansion in $f(R, G)$ gravity using a log-periodic deceleration model
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arXiv
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| Format: | Preprint |
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2025
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| author | Samaddar, Amit Singh, S. Surendra |
| author_facet | Samaddar, Amit Singh, S. Surendra |
| contents | We study the late-time cosmology in $f(R, G)=R+αR^{2}+βe^{γG}$, using a logarithmic parametrization of the deceleration parameter $q(z)=q_{0}+q_{1}sin[log(1+z)]$. The Hubble parameter $H(z)$ is reconstructed and model parameters are constrained via MCMC analysis using CC ($31$), BAO ($26$) and Pantheon+SHOES ($1701$) datasets. Our results yield a Hubble constant in the range $H_0 = 71.7$--$72.8$ km/s/Mpc, consistent with late-time observations. The present deceleration parameter is found to be $q_{0}=-0.484$ to $-0.517$, while the evolution parameter $q_{1}\approx 1$, indicating increasing acceleration. The transition redshift shifts from $z_{tr}=0.879$ (CC) to $0.744$ (CC+BAO+Pantheon+SHOES), supporting a dynamic acceleration phase. The model reproduces early radiation behavior with $ω(z>>1) \approx 0.33$ and predicts present-day values $ω_{0} \approx -0.49$. Energy conditions NEC and DEC are satisfied, while SEC is violated at late times. The statefinder parameters $\{r_0, s_0\} = (0.866, 0.046)$ lie near the $Λ$CDM point. Estimated age of the Universe ranges from $13.01$ to $13.59$ Gyr. Thermodynamic analysis confirms consistency with the generalized second law. Overall, the model offers a viable and observationally consistent description of cosmic acceleration. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_06388 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Reconstructing cosmic expansion in $f(R, G)$ gravity using a log-periodic deceleration model Samaddar, Amit Singh, S. Surendra General Relativity and Quantum Cosmology We study the late-time cosmology in $f(R, G)=R+αR^{2}+βe^{γG}$, using a logarithmic parametrization of the deceleration parameter $q(z)=q_{0}+q_{1}sin[log(1+z)]$. The Hubble parameter $H(z)$ is reconstructed and model parameters are constrained via MCMC analysis using CC ($31$), BAO ($26$) and Pantheon+SHOES ($1701$) datasets. Our results yield a Hubble constant in the range $H_0 = 71.7$--$72.8$ km/s/Mpc, consistent with late-time observations. The present deceleration parameter is found to be $q_{0}=-0.484$ to $-0.517$, while the evolution parameter $q_{1}\approx 1$, indicating increasing acceleration. The transition redshift shifts from $z_{tr}=0.879$ (CC) to $0.744$ (CC+BAO+Pantheon+SHOES), supporting a dynamic acceleration phase. The model reproduces early radiation behavior with $ω(z>>1) \approx 0.33$ and predicts present-day values $ω_{0} \approx -0.49$. Energy conditions NEC and DEC are satisfied, while SEC is violated at late times. The statefinder parameters $\{r_0, s_0\} = (0.866, 0.046)$ lie near the $Λ$CDM point. Estimated age of the Universe ranges from $13.01$ to $13.59$ Gyr. Thermodynamic analysis confirms consistency with the generalized second law. Overall, the model offers a viable and observationally consistent description of cosmic acceleration. |
| title | Reconstructing cosmic expansion in $f(R, G)$ gravity using a log-periodic deceleration model |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2506.06388 |