Primordial gravity waves in a rainbow background

The dawn of the epoch of gravitational wave (GW) astronomy, which initiated with the detection of a fundamental noise, was the period when the search for a theory in which gravity could be quantized began to increase significantly. In this paper, we have mainly intended to focus on the polar modes of GWs in the formalism of gravity’s rainbow, which is based on the product of the disparity between quantum mechanics and general relativity (GR). For this purpose, we have perturbed the spatially flat conformal Friedmann-Lemaitre-Robertson-Walker metric, material distribution and the components of four-velocity by making use of the polar Regge-Wheeler gauge and formulated the corresponding field equations for both the zeroth-order (unperturbed) and the first-order (perturbed) cases of the metric. Subsequently, these field equations have been taken into account simultaneously to get exact expressions of the gauge functions. From a graphical perspective, we have studied the impact of rainbow parameters on the amplitude of GWs. In the last step, discussing the Huygens Principle, we have concluded that the GWs obey the principle only in the radiation-dominated era and the principle is broken otherwise.