We extend the CCEGA framework to a five-dimensional scenario to investigate the stability of compact objects in the strong-field regime. We demonstrate that the exponential curvature-matter coupling induces a regular black hole metric with a de Sitter core, effectively avoiding the central singularity. We explicitly connect the regularization scale Rc to the vacuum expectation value of a stabilized radion in the bulk. Through a perturbation analysis based on the sixth-order WKB method, we characterize the resulting gravitational wave echoes. The dynamics of the radion introduce a characteristic modulation, generating frequency sidebands in the echo signal. Our results suggest that this fine structure provides a unique observational signature, detectable by third-generation interferometers such as LISA or the Einstein Telescope.
López Sánchez Marc (2025) studied this question.