Gravitational waves with dark energy

Abstract

In this article, we study the tensor mode equation of perturbation in the presence of nonzero−Λ as dark energy, the dynamic nature of which depends on the Hubble parameter H and/or its time derivative. Dark energy, according to the total vacuum contribution, has a slight effect during the radiation-dominated era, but it reduces the squared amplitude of gravitational waves (GWs) up to 60% for the wavelengths that enter the horizon during the matter-dominated era. Moreover, the observations bound on dark energy models, such as running vacuum model (RVM), generalized running vacuum model (GRVM) and generalized running vacuum subcase (GRVS), are effective in reducing the GWs' amplitude. Although this effect is less for the wavelengths that enter the horizon at later times, this reduction is stable and permanent.