Description
After the motivation for frameworks beyond Einstein's gravity and the ΛCDM paradigm, we explain the Cosmology of the Einstein-dilaton-Gauss-Bonnet (EdGB) gravity, one of the simplest extensions through the inclusion of higher-curvature terms. Particular attention is given to the emergence of a novel phase within dEGB cosmology at high temperatures, supplementing the established radiation, matter, and dark energy-dominated phases characteristic of the ΛCDM model. Out of the many implication of EdGB cosmology, the main focus is on the Cosmic Gravitational Microwave Background (CGMB) from the hot plasmas consisting of the standard model particles in the early universe whose peak frequency is close to 100GHz. We point out that CGMB can be enhanced up to the visible range for the detectors near future with the present technology. This should lead either to the new discovery of the Ultra High Frequency gravitational waves of CGMB or the constraints to the EdGB theory if not.