Probing leptogenesis and the minimal neutrino seesaw mechanism through gravitational waves

We propose that a gravitational wave can be generated during leptogenesis in the early Universe, which occurs during heavy right-handed neutrino decay. Such a gravitational wave, as a remnant of leptogenesis, is shown to be associated with distinguishing signatures that not only act as a powerful probe to leptogenesis but also to the existence of heavy seesaw states, which otherwise remain difficult to validate despite their success in explaining the baryon asymmetry of the Universe, closely connected to the origin of neutrino mass.