Characterization of gravitational radiation at infinity with a cosmological constant

The existence or absence of gravitational radiation escaping from the spacetime at $\mathscr{J}$ is characterized in the presence of a cosmological constant $\Lambda$ of any sign. To that end, the properties of the asymptotic super-momentum are used. When $\Lambda=0$, the characterization is equivalent to that based on the News tensor. For $\Lambda\neq 0$, it provides the first reliable definition of existence of radiation at $\mathscr{J}$, and it gives fully satisfactory results in known exact solutions.