Gravitational waves from resonant amplification of curvature\n perturbations during inflation

Abstract

Parametric resonance in a single-field inflationary model with a periodic\nstructure on the potential gives rise to curvature perturbations with large\namplitudes on small scales, which could result in observable primordial black\nholes (PBHs) and concomitant gravitational waves (GWs) induced by curvature\nperturbations in the radiation-dominated era. In such a model, GWs associated\nwith the PBH formation were investigated in Ref. [1]. In this paper, we\nconsider a stochastic GW background sourced by inflaton perturbations\nresonantly amplified during inflation. We compute the energy spectra of induced\nGWs produced both during inflation and in the radiation-dominated era, and find\nthat the peak of the energy spectrum of the former is much higher than that of\nthe latter, but is located at a lower frequency. Moreover, the energy spectrum\nof induced GWs produced during inflation exhibits a unique oscillating\ncharacter in the ultraviolet region. Both the stochastic GW backgrounds are\nexpected to be detected by future space-based laser interferometers.\n