Primordial gravitational waves spectrum in the interacting Bose–Einstein gas model

We study the evolution and power spectrum of primordial gravitational waves in the interactive Bose–Einstein gas model for dark energy, relevant, as it addresses the coincidence problem. The model is applied in the radiation, matter and dark-energy domination stages. The model introduces a scale factor associated to the radiation-matter transition which influences the gravitational spectrum. We focus on the impact of the free parameters on both the gravitational waves amplitude and its power-spectrum slope. For sets of parameters fitting Hubble’s law, we show that the model’s parameter for today’s dark-matter energy density, the mass component, has a noticeable impact on such waves, while the others produce an indistinguishable effect. The feasibility of detecting such waves under present and future measurements is discussed.