Measuring accretion-disk effects with extreme-mass-ratio inspirals

Extreme-mass-ratio inspirals (EMRIs) are binary systems in which a small compact object orbits into a supermassive black hole. They are primary targets for the planned LISA mission, since the precision of their measured parameters allows for unparalleled tests of general relativity, as well as astrophysical and cosmological inference. Because of this, EMRI waveforms must be very accurate to capture deviations from general-relativistic predictions due to either modifications of the theory of gravity or the environs of the central supermassive black hole. In this talk I discuss how future detections of EMRIs can be used to measure parameters related to the accretion disks surrounding the massive black hole in the binary. The effects taken into consideration (and included in state-of-the-art EMRI models) are planetary-type migration, winds and dynamical friction. All of these lead to potentially large modifications of the secondaries' trajectories that depend on the accretion-disk parameters. I will present order-of-magnitude estimates for the detectability of such parameters, alongside a more sophisticated Monte Carlo analysis for the most promising effect.