The role of black-hole gravitational recoils in multi-messenger astronomy

Gravitational waves (GWs) carry linear momentum. As a consequence, due to the asymmetry of the GW emission, the remnant of a black hole of a black-hole merger can inherit a recoil speed, known as “kick”, which can exceed the scape velocity of the host environment. The magnitude of a black-hole kick has fundamental implications in black-hole formation and while its direction is key to understanding the plausibility of potential multi-messenger observations of black-hole mergers. In this talk I will report the first complete characterisation of the gravitational recoil of a remnant black-hole (that of GW190412). In addition, I will discuss potential applications, with preliminary results, to multi-messenger observations of black-hole mergers in, e.g., active galactic nuclei.