arXiv subjects

Theppawan Rukpakawong

Publications and source records attributed to Theppawan Rukpakawong.

2 recordsLinked to original sources

arXiv2026

Constraints on Quintom Dark Energy Model with Matter Interaction

The quintom model consisting of quintessence and phantom scalar fields with linear coupling to matter is explored and constrained by updated DESI and supernovae type Ia~(SNIa) observational data. The matter interaction is assumed only between phantom and matter and the quintessence self potential is in an exponential form. The quintom evolution shows a class of solutions with phantom crossing scenario consistent with the current DESI data. From low redshift observations, we place constraints on the model with BAO data from DESI and distance measurements from SNIa Pantheon+ samples and SH0Es. For high-redshift constraints, we use CMB priors from Planck and found that the quintom model gives the best-fit Hubble parameter $H_{0}=65.780~(68.736)$~km s$^{-1}$ Mpc$^{-1}$ for DESI+CMB+SNIa~(+SH0ES) respectively. The marginalized statistical constrained values are $H_{0}=66.21\pm 0.84~(68.49^{+0.46}_{-0.40})$~km s$^{-1}$ Mpc$^{-1}$ for DESI+CMB+SNIa~(+SH0ES) respectively. Using the BBN prior for high-redshift constraints, the corresponding best-fit values for DESI+BBN+SNIa~(+SH0ES) constraints are $H_{0}=63.999~(71.962)$~km s$^{-1}$ Mpc$^{-1}$ and the marginalized statistical values for DESI+BBN+SNIa~(+SH0ES) constraints are $H_{0}=61.6^{+6.6}_{-3.0}~(71.86\pm 0.88)$~km s$^{-1}$ Mpc$^{-1}$ respectively. Generally, adding SH0ES significantly raises the best-fit and marginalized value of $H_{0}$ for all datasets. In comparison to $Λ$CDM, the interacting quintom model gives lower values of $σ_{8}=0.74-0.79$ for combination of datasets with CMB prior. Lastly, the fifth-force constraint from local scale solar system Cassini probe is estimated, we find the constraint on the phantom-matter coupling $|δ|<3.3\times 10^{-3}$.

gr-qc↗

arXiv2025

The effective phase space and $e$-folding of the Starobinsky and extended Starobinsky model of inflation

For zero spatial curvature, cosmological phase space of Starobinsky and extended Starobinsky inflationary model show three apparent attractors; the fixed angle attractor in the large field limit, the final attractor representing reheating phase in the small field region, and the apparent attractor corresponding to the slow-roll condition connecting between the large-field and small-field region. To consider the total $e$-folding likelihood of the model, Remmen-Carroll conserved measure is constructed and normalized. Using the measure, the total e-folding number $N$ and its expectation value $\left\langle N \right\rangle$ are calculated. Our results show that most classical slow-roll trajectories which intersect the Planck surface have $N<60$, and $ϕ_{\rm UV}>5.5 M^{*}_{\rm Pl}$ is required for $N>60$. It is found that for $ϕ_{\rm UV}\in [5.22,5.50]M^{*}_{\rm Pl}$ which satisfies the constraint on the spectral index, $n_s = 0.9658 \pm 0.0040\,\,\,(68\%\,\,{\rm CL})$, the expectation value $\langle N \rangle \simeq 3.5 - 4$ for trajectories intersecting the Planck surface in the Starobinsky model. For extended Starobinsky model with additional $R^3$ term parametrized by a coupling parameter $α$, the expectation value when inflation starts from the top of the potential shifts to $\left\langle N \right\rangle = 4.025,4.336$ for $α= 10^{-4},6.5\times 10^{-5}$ respectively. In the Starobinsky model even at very large inflaton cutoff $ϕ_{\rm UV}$ where the field value is super-Planckian, the energy density from the (saturating) inflaton potential and the Hubble parameter are still sub-Planckian and therefore the inflation occurs within the semi-classical regime.

gr-qc↗