Speaker
Description
Can gravitational waves reveal the properties of dark matter? Compact binaries embedded in extended dark matter configurations provide a unique opportunity to probe the macroscopic behavior of the dark sector. If a neutron star or black hole is surrounded by a sufficiently massive and extended dark matter envelope, an inspiraling companion experiences dynamical friction in addition to the standard gravitational-wave energy loss. This environmental effect can be isolated through a new gravitational-wave observable, the $D$-function, which directly measures the extra dissipative power induced by the surrounding medium. Since the density profile of the envelope is determined by the dark matter equation of state, the frequency dependence of the $D$-function encodes direct information about the equation of state itself. Through a regression-based framework, we may reconstruct both the density profile and the dark matter equation of state from gravitational-wave observations. This method accurately recovers the input equation of state while remaining largely independent of the microscopic nature of dark matter. These results illustrate how future gravitational-wave observations could provide a new window into the fundamental properties of dark matter.