Gravitational waves from oscillons in a generalized exponential plateau potential

Abstract

We study oscillon formation and gravitational wave production in a generalized exponential plateau inflationary potential. Using Floquet analysis, we identify parametric instability bands consistent with oscillon formation, and solve numerically for the oscillon profile, finding quasi-breather solutions with lifetimes $\ddot{I}{„}_{\mathrm{osc}}\cdot m_{\mathrm{eff}}\sim 10^3$ --- $6\times 10^4$. Applying the poltergeist mechanism, we compute the induced gravitational wave spectrum and find a peak at $f_{\mathrm{peak}}\approx 2.5\times 10^{10}$~Hz with amplitude $\hat{I}{\text{c◯}}_{\mathrm{GW},0}{h}^2\sim 10^{-9}$--$10^{-8}$ for the benchmark parameter ${\hat{I}}_{\mathrm{pot}}^2=5\times 10^{-6}$. This is far below the region forbidden by big bang nucleosynthesis. For ${\hat{I}}_{\mathrm{pot}}^2=5\times 10^{-5}$ the signal exceeds the big bang nucleosynthesis bound for all considered oscillon energy fractions, constraining the parameter space of the model. The signal falls in the GHz regime, potentially accessible to future resonant cavity experiments.