Gravitational waves in hybrid quintessential inflation

Paulo M. Sá and A. B. Henriques

We analyse the generation of primordial gravitational waves in the hybrid quintessential inflationary model proposed recently by Bastero-Gil et al. Using the method of continuous Bogoliubov coefficients, we calculate the full gravitational-wave energy spectrum. The post-inflationary kination period, characteristic of quintessential inflationary models, leaves a clear signature on the spectrum, namely, a peak on the MHz-GHz region of frequencies. For appropriate values of the parameters of the model, the gravitational-wave spectral energy density $Omega_{GW}$ can be as high as 10⁻¹².