Cosmological insights from an exponential $Om(z)$ function in $f(T,T_{G})$ gravity framework
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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 examine a modified teleparallel gravity model defined by $f(T,T_{G})=T+γ\sqrt{T_{G}}+δ\sqrt{T}$ by introducing an exponential $Om(z)$ diagnostic of the form $Om(z)=αe^{\frac{z}{1+z}}+β$. This novel form captures smooth redshift evolution and allows for a flexible, model-independent probe of dark energy dynamics. We derive a Hubble function from this expression and use MCMC analysis with $31$ CC, $26$ BAO and $1701$ Pantheon+ data points to constrain the model parameters. The best-fit results yield $H_{0} \in [68.46, 77.38]$km/s/Mpc for $α\in [-0.232, -0.068]$ and $β\in [0.218, 0.560]$ which is consistent with local $H_{0}$ values. Our model predicts a transition redshift $z_{tr} \approx (0.48-0.54)$, present $q_{0}\approx -0.34$, and $ω_{0}\approx-0.33$. It satisfies NEC and DEC, closely tracks $Λ$CDM in the statefinder plane and estimates a cosmic age of $(13.28-13.87)$ Gyr which confirms its strength in explaining late-time acceleration. Our findings demonstrate that the exponential $Om(z)$ parameterization provides a robust and insightful approach to trace dark energy evolution within modified gravity frameworks. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2506_06399 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Cosmological insights from an exponential $Om(z)$ function in $f(T,T_{G})$ gravity framework Samaddar, Amit Singh, S. Surendra General Relativity and Quantum Cosmology We examine a modified teleparallel gravity model defined by $f(T,T_{G})=T+γ\sqrt{T_{G}}+δ\sqrt{T}$ by introducing an exponential $Om(z)$ diagnostic of the form $Om(z)=αe^{\frac{z}{1+z}}+β$. This novel form captures smooth redshift evolution and allows for a flexible, model-independent probe of dark energy dynamics. We derive a Hubble function from this expression and use MCMC analysis with $31$ CC, $26$ BAO and $1701$ Pantheon+ data points to constrain the model parameters. The best-fit results yield $H_{0} \in [68.46, 77.38]$km/s/Mpc for $α\in [-0.232, -0.068]$ and $β\in [0.218, 0.560]$ which is consistent with local $H_{0}$ values. Our model predicts a transition redshift $z_{tr} \approx (0.48-0.54)$, present $q_{0}\approx -0.34$, and $ω_{0}\approx-0.33$. It satisfies NEC and DEC, closely tracks $Λ$CDM in the statefinder plane and estimates a cosmic age of $(13.28-13.87)$ Gyr which confirms its strength in explaining late-time acceleration. Our findings demonstrate that the exponential $Om(z)$ parameterization provides a robust and insightful approach to trace dark energy evolution within modified gravity frameworks. |
| title | Cosmological insights from an exponential $Om(z)$ function in $f(T,T_{G})$ gravity framework |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2506.06399 |