Abstract:

The inspiral of a stellar-mass compact object into a supermassive black hole—an Extreme Mass-Ratio Inspiral (EMRI)—is one of the most pristine dynamical systems in the universe. They represent a unique observational opportunity: EMRIs act as fundamental test particles performing a high-resolution, long-term scan of a highly curved spacetime.

In this talk, I will introduce the fundamentals of EMRIs. Over the course of hundreds of thousands of orbits, the smaller body slowly deviates from pure geodesic flow due to its own gravitational self-force (radiation reaction). Because this adiabatic evolution is incredibly sensitive to the surrounding curvature, the resulting gravitational waves encode the multipolar structure of the background metric of warped spacetime.

I will discuss how we can use these millions of phase cycles to reconstruct the local spacetime geometry, test the Kerr hypothesis, and probe the boundary conditions of the event horizon itself. Ultimately, this talk aims to demonstrate how future space-borne gravitational wave observatories will provide a direct, empirical window into the pure geometry of strong-field gravity.