arXiv subjects

Iraj Safaei

Publications and source records attributed to Iraj Safaei.

2 recordsLinked to original sources

arXiv2025

Mutated hilltop inflation in light of Planck/ACT observations

Here, a single field inflationary model driven by a mutated hilltop potential, a subclass of the hilltop models of inflation, is investigated. To constrain the parameter space, we employ the latest $r-n_{\rm s}$ constraints from Planck 2018, BICEP/Keck 2018, and the Atacama Cosmology Telescope (ACT) data, alongside reheating parameters $N_{\rm{re}}$, $T_{\rm{re}}$, and $ω_{\rm{re}}$, and the model independent bound on the radiation dominated (RD) era $N_{\rm{rd}}$. Furthermore, the relic gravitational wave (GW) spectrum within the sensitivity domains of future GW detectors are analyzed. By combining CMB, reheating, RD era, and GW constraints, we find for the Planck+BK18 data that the inflationary duration is confined to $46 \leq N \leq 56$ (95\% CL) and $48.1 \leq N \leq 56$ (68\% CL). Moreover, the model parameter $α$ is confined to $0.161 \leq α\leq 0.890$ (95\% CL) and $0.217 \leq α\leq 0.815$ (68\% CL). Inclusion of the ACT data further tighten the constraints to $54 \leq N \leq 56$ (95\% CL) and $0.29 \leq α\leq 0.62$ (95\% CL), thereby enhancing the precision and robustness of the model predictions.

astro-ph.CO↗

arXiv2025

Breaking the degeneracy of non-canonical quartic inflation by reheating considerations

Here, the quartic inflationary potential $V(ϕ)=\fracλ{4}ϕ^4$ within a non-canonical framework characterized by a power-law Lagrangian is investigated. We demonstrate that the predictions of this model align with the Planck 2018 observational data. We explore how the predictions of the model depend on the non-canonical parameter $α$ and the number of $e$-folds $N$. Notably, the sound speed, non-Gaussianity parameter, scalar spectral index, and tensor-to-scalar ratio are all affected by variations in $α$. However, the scalar spectral index exhibits a degeneracy with respect to variation in $α$, which can be broken by incorporating reheating consideration. By applying a combination of theoretical and observational constraints on $(r-n_{\rm s})$, non-Gaussianity, and reheating parameters, we find that the duration of inflation is constrained to the range $55 \leq N\leq55.7$ $e$-folds for $60 \leq α\leq 130$. Finally, we investigate relic gravitational waves and demonstrate that their energy density spectrum falls within the sensitivity range of gravitational waves detectors for this constrained range of $e$-folds.

gr-qc↗