Induced Gravitational Waves as Cosmic Tracers of Leptogenesis

We demonstrate that induced gravitational waves (IGWs) can naturally emerge within well-motivated realizations of thermal leptogenesis, thereby providing a possible observational handle on this framework at remarkably high energy scales. To illustrate this principle, we put forth a simple leptogenesis model in which an early matter-dominated phase, connected to the leptogenesis scale, enhances the generation of gravitational waves induced by early structure formation. Leveraging recent N-body and lattice simulation results for IGW computations in the non-linear regime, we show that, within the assumptions of the model, the frequency and amplitude of these IGWs can be correlated with the thermal leptogenesis scale.