We study gravitational wave production in an expanding Universe during the first stages following inflation, and investigate the consequences of the Gauss–Bonnet term on the inflationary parameters for a power-law inflation model with a GB coupling term. Moreover, we perform the analyses on the preheating parameters involving the number of e-folds $$N_{pre}$$ N pre , and the temperature of thermalization $$T_{th},$$ T th , and show that it’s sensitive to the parameters n, and $$\gamma $$ γ , the parameter $$\gamma $$ γ is proposed to connect the density energy at the end of inflation to the preheating energy density. We set a correlation of gravitational wave energy density spectrum with the spectral index $$n_{s}$$ n s detected by the cosmic microwave background experiments. The density spectrum $$\varOmega _{gw}$$ Ω gw shows good consistency with observation for $$\gamma =$$ γ = $$10^{3}$$ 10 3 and $$10^{6}$$ 10 6 . Our findings suggest that the generation of gravitational waves (GWs) during preheating can satisfy the constraints from Planck’s data.

No abstract

No abstract

We propose a scenario where preheating occurs for a specific duration that is parametrized by an [Formula: see text]-folds number [Formula: see text], our results suggest a direct correlation between the preheating duration and the density of gravitational waves (GWs) produced during this phase. Moreover, we investigate the consequences of the inflationary parameters on the [Formula: see text]-attractor [Formula: see text] model in the small [Formula: see text] limits. In this framework, we perform investigations on the preheating parameters involving the number of [Formula: see text]-folds [Formula: see text], and the temperature of reheating [Formula: see text], then we show that the parameter [Formula: see text] associated with the [Formula: see text] model of [Formula: see text]-attractor inflation has a negligible effect on the preheating duration, and we demonstrate that gravitational wave generation during preheating satisfies the restrictions from Planck’s recent data.