Detecting environmental effects

Gravitational-wave observations of extreme mass ratio inspirals (EMRIs) hold incredible potential to probe gravity, astrophysical and exotic environments. One of the main effects of astrophysical environments — in particular active galactic nuclei — is the torque exerted by their gaseous disk, which forces EMRIs to “migrate” (mostly) inward like planets. We will review this effect, and present a Bayesian model-independent framework to detect and characterise these environments with LISA.