Gravitational waves, LISA and Extreme Mass Ratio Inspirals

An extreme mass ratio inspiral (EMRI) is a binary system, in which a secondary stellar compact object orbits around a primary supermassive black hole and slowly drifts towards the primary due to gravitational radiation reaction. EMRIs are one of the prominent targets of in development mHz gravitational wave (GW) observatories like the Laser Interferometer Space Antenna (LISA). GW signals from EMRIs are promising to test our theoretical expectations about black holes and general relativity with unprecedented accuracy. We shall discuss the challenges ahead that have to be addressed in order to realize these promises.