Universal gravitational self-force for a point mass orbiting around a compact star

In this work, we study the gravitational back-reaction (i.e., the “self-force”) of a point mass moving around a non-rotating, compact star on a circular orbit. We find that the additional self-force, comparing with the case with a point mass orbiting around a Schwarzschild black hole, can be well characterized by an universal frequency-dependent function multiplied by the (dynamical) tidal deformability of the compact star. This finding provides the foundation for building the waveform model for an extreme mass-ratio inspiral system around a star-like black hole mimicker, which is relevant for testing General Relativity and exotic compact objects with space-borne gravitational wave detectors.